Classification of Compounds on the Basis of Chemical Properties Compounds are placed in three broad classes.
Acids – sour in taste; turn blue litmus red.
Bases – bitter, soapy to touch; turn red litmus blue.
Salts – formed when acids react with bases; normally taste salty, though some possess unpleasant or even poisonous flavour.
Indicators Substances/dyes that change colour (or odour) in acidic vs. basic media.
Laboratory / Synthetic Indicators • Litmus solution – purple dye extracted from lichens.
Natural Indicators and Their Behaviour • Turmeric (Curcuma longa) – acid: remains yellow; base: turns red–brown.
Olfactory Indicators (change/lose odour) • Onion extract – odourless in base; retains smell in acid.
Litmus Extraction (Natural Indicator Preparation) Purple litmus dye is obtained by pulverising lichens, boiling with water, filtering, and concentrating the filtrate. It is then formulated as paper strips or an aqueous solution.
Acids Sources / Types Organic acids – produced naturally in plants & animals (exception: gastric HCl \text{HCl} HCl
Mineral (inorganic) acids – synthesised from minerals of earth’s crust.
Strength •
Strong acids – ionise completely in water, e.g
. HCl , H<em>2SO</em>4 , HNO<em>3 . \text{HCl},\; \text{H<em>2SO</em>4},\; \text{HNO<em>3}. HCl , H<em>2SO</em>4 , HNO<em>3 . Weak acids – partial ionisation, e.g. \text{CH 3COOH},\; \text{H2CO 3}.$
$
Concentrated vs. Dilute • Concentrated acid contains minimum water; dilute acid contains substantial added water.
Precaution in Dilution Always add acid to water , never water to acid – dilution is exothermic; splashing/boiling can result if water is poured onto concentrated acid.
General Properties of Acids • Sour taste, corrosive, conduct electricity (due to \text{H}^+/ / / ) . < b r > • R e a c t i v i t y p a t t e r n s : < / p > < o l > < l i > < p > M e t a l + A c i d → S a l t + ). <br>• Reactivity patterns:</p><ol><li><p>Metal + Acid → Salt + ) . < b r > • R e a c t i v i t y p a tt er n s :< / p >< o l >< l i >< p > M e t a l + A c i d → S a lt + 2 3 \rightarrow Zn(NO3) 2 + H_2}< / p > < / l i > < l i > < p > M e t a l c a r b o n a t e / h y d r o g e n c a r b o n a t e + A c i d → S a l t + </p></li><li><p>Metal carbonate/hydrogencarbonate + Acid → Salt + < / p >< / l i >< l i >< p > M e t a l c a r b o na t e / h y d ro g e n c a r b o na t e + A c i d → S a lt + 2+ + + 2\text{O}< b r > <br> < b r > 2CO 3 + 2HCl \rightarrow 2NaCl + CO2 + H 2O}< b r > <br> < b r > 3 + HCl \rightarrow NaCl + CO 2 + H_2O}< / p > < / l i > < l i > < p > M e t a l o x i d e ( b a s i c o x i d e ) + A c i d → S a l t + </p></li><li><p>Metal oxide (basic oxide) + Acid → Salt + < / p >< / l i >< l i >< p > M e t a l o x i d e ( ba s i co x i d e ) + A c i d → S a lt + 2\text{O} 2 + H_2O}< / p > < / l i > < l i > < p > A c i d + B a s e → S a l t + W a t e r ( n e u t r a l i s a t i o n ) < b r > </p></li><li><p>Acid + Base → Salt + Water (neutralisation) <br> < / p >< / l i >< l i >< p > A c i d + B a se → S a lt + Wa t er ( n e u t r a l i s a t i o n ) < b r > < / p > < / l i > < / o l > < h 5 i d = " 25651 a 7 c − 73 d c − 49 b 1 − 8 b c d − 34 c b e 3 d 6 c 25 d " d a t a − t o c − i d = " 25651 a 7 c − 73 d c − 49 b 1 − 8 b c d − 34 c b e 3 d 6 c 25 d " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > R e p r e s e n t a t i v e A c t i v i t i e s < / h 5 > < p > • Z i n c + d i l u t e </p></li></ol><h5 id="25651a7c-73dc-49b1-8bcd-34cbe3d6c25d" data-toc-id="25651a7c-73dc-49b1-8bcd-34cbe3d6c25d" collapsed="false" seolevelmigrated="true">Representative Activities</h5><p>• Zinc + dilute < / p >< / l i >< / o l >< h 5 i d = "25651 a 7 c − 73 d c − 49 b 1 − 8 b c d − 34 c b e 3 d 6 c 25 d " d a t a − t oc − i d = "25651 a 7 c − 73 d c − 49 b 1 − 8 b c d − 34 c b e 3 d 6 c 25 d " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > R e p rese n t a t i v e A c t i v i t i es < / h 5 >< p > • Z in c + d i l u t e 2\text{SO} 4: c o l l e c t i o n o f : collection of : co ll ec t i o n o f 2i n s o a p b u b b l e s i g n i t e s w i t h a ‘ p o p ’ . • in soap bubbles ignites with a ‘pop’. • in so a p b u bb l es i g ni t es w i t ha ‘ p o p ’.• 3/ / / 3w i t h with w i t h : : : 2t u r n s l i m e − w a t e r m i l k y ( turns lime-water milky ( t u r n s l im e − w a t er mi l k y ( 3p p t . ) , e x c e s s ppt.), excess ppt . ) , e x cess 2c l e a r s m i l k i n e s s ( s o l u b l e clears milkiness (soluble c l e a rs mi l kin ess ( so l u b l e 3) 2) . < / p > < d i v d a t a − t y p e = " h o r i z o n t a l R u l e " > < h r > < / d i v > < h 4 i d = " 2 f 14908 e − 99 e 0 − 40 e 9 − 80 c c − 942 e e 5 c c a 2 e 8 " d a t a − t o c − i d = " 2 f 14908 e − 99 e 0 − 40 e 9 − 80 c c − 942 e e 5 c c a 2 e 8 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > A c i d s R e q u i r e W a t e r f o r A c i d i t y < / h 4 > < p > D r y ).</p><div data-type="horizontalRule"><hr></div><h4 id="2f14908e-99e0-40e9-80cc-942ee5cca2e8" data-toc-id="2f14908e-99e0-40e9-80cc-942ee5cca2e8" collapsed="false" seolevelmigrated="true">Acids Require Water for Acidity</h4><p>Dry ) . < / p >< d i v d a t a − t y p e = " h or i zo n t a lR u l e " >< h r >< / d i v >< h 4 i d = "2 f 14908 e − 99 e 0 − 40 e 9 − 80 cc − 942 ee 5 cc a 2 e 8" d a t a − t oc − i d = "2 f 14908 e − 99 e 0 − 40 e 9 − 80 cc − 942 ee 5 cc a 2 e 8" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > A c i d s R e q u i re Wa t er f or A c i d i t y < / h 4 >< p > Dry g a s s h o w s n o l i t m u s c h a n g e u n t i l m o i s t ; gas shows no litmus change until moist; g a ss h o w s n o l i t m u sc han g e u n t i l m o i s t ; e x i s t s a s h y d r o n i u m exists as hydronium e x i s t s a s h y d ro ni u m
Bases Definition & Common Traits • Bitter, soapy, turn red litmus blue, conduct electricity (provide \text{OH}^-i n w a t e r ) . < / p > < h 5 i d = " 77 c 94 b 08 − b a 65 − 4545 − 8 c 4 a − 37127 c 0 f e 8 a e " d a t a − t o c − i d = " 77 c 94 b 08 − b a 65 − 4545 − 8 c 4 a − 37127 c 0 f e 8 a e " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > S t r o n g v s . W e a k B a s e s < / h 5 > < p > • S t r o n g ( c o m p l e t e i o n i s a t i o n ) : in water).</p><h5 id="77c94b08-ba65-4545-8c4a-37127c0fe8ae" data-toc-id="77c94b08-ba65-4545-8c4a-37127c0fe8ae" collapsed="false" seolevelmigrated="true">Strong vs. Weak Bases</h5><p>• Strong (complete ionisation): in w a t er ) . < / p >< h 5 i d = "77 c 94 b 08 − ba 65 − 4545 − 8 c 4 a − 37127 c 0 f e 8 a e " d a t a − t oc − i d = "77 c 94 b 08 − ba 65 − 4545 − 8 c 4 a − 37127 c 0 f e 8 a e " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > St ro n gv s . W e ak B a ses < / h 5 >< p > • St ro n g ( co m pl e t e i o ni s a t i o n ) : < b r > • W e a k ( p a r t i a l ) : <br>• Weak (partial): < b r > • W e ak ( p a r t ia l ) : 4\text{OH},\; \text{Ca(OH)} 2.< / p > < h 5 i d = " e 89 c c a 6 a − d 90 f − 414 a − b a 72 − 037 e e 808 d 277 " d a t a − t o c − i d = " e 89 c c a 6 a − d 90 f − 414 a − b a 72 − 037 e e 808 d 277 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > A l k a l i s < / h 5 > < p > W a t e r − s o l u b l e b a s e s ; a l l a l k a l i s a r e b a s e s b u t n o t e v e r y b a s e i s a n a l k a l i ( e . g . </p><h5 id="e89cca6a-d90f-414a-ba72-037ee808d277" data-toc-id="e89cca6a-d90f-414a-ba72-037ee808d277" collapsed="false" seolevelmigrated="true">Alkalis</h5><p>Water-soluble bases; all alkalis are bases but not every base is an alkali (e.g. < / p >< h 5 i d = " e 89 cc a 6 a − d 90 f − 414 a − ba 72 − 037 ee 808 d 277" d a t a − t oc − i d = " e 89 cc a 6 a − d 90 f − 414 a − ba 72 − 037 ee 808 d 277" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > A l ka l i s < / h 5 >< p > Wa t er − so l u b l e ba ses ; a ll a l ka l i s a re ba ses b u t n o t e v ery ba se i s ana l ka l i ( e . g . i n s o l u b l e ) . < / p > < h 5 i d = " d 3 b e 5 f 60 − a 2 a 6 − 4671 − b e 7 d − c f f a 9 d 600 a 6 c " d a t a − t o c − i d = " d 3 b e 5 f 60 − a 2 a 6 − 4671 − b e 7 d − c f f a 9 d 600 a 6 c " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > I m p o r t a n t R e a c t i o n s < / h 5 > < o l > < l i > < p > M e t a l + B a s e ( s o m e m e t a l s s u c h a s Z n , A l ) → S a l t + insoluble).</p><h5 id="d3be5f60-a2a6-4671-be7d-cffa9d600a6c" data-toc-id="d3be5f60-a2a6-4671-be7d-cffa9d600a6c" collapsed="false" seolevelmigrated="true">Important Reactions</h5><ol><li><p>Metal + Base (some metals such as Zn, Al) → Salt + in so l u b l e ) . < / p >< h 5 i d = " d 3 b e 5 f 60 − a 2 a 6 − 4671 − b e 7 d − c ff a 9 d 600 a 6 c " d a t a − t oc − i d = " d 3 b e 5 f 60 − a 2 a 6 − 4671 − b e 7 d − c ff a 9 d 600 a 6 c " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > I m p or t an tR e a c t i o n s < / h 5 >< o l >< l i >< p > M e t a l + B a se ( so m e m e t a l ss u c ha s Z n , A l ) → S a lt + 2 2ZnO2 + H 2}( s o d i u m z i n c a t e ) . < / p > < / l i > < l i > < p > N o n − m e t a l o x i d e ( a c i d i c ) + B a s e → S a l t + (sodium zincate).</p></li><li><p>Non-metal oxide (acidic) + Base → Salt + ( so d i u m z in c a t e ) . < / p >< / l i >< l i >< p > N o n − m e t a l o x i d e ( a c i d i c ) + B a se → S a lt + 2\text{O} 2 + CO2 \rightarrow CaCO 3 + H_2O}. < / p > < / l i > < l i > < p > N e u t r a l i s a t i o n a l r e a d y n o t e d a b o v e . < / p > < / l i > < / o l > < h 5 i d = " 273 a 9 e 87 − a 7 c c − 452 a − a 3 a a − 45 c a f e f 39 a 78 " d a t a − t o c − i d = " 273 a 9 e 87 − a 7 c c − 452 a − a 3 a a − 45 c a f e f 39 a 78 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > A m p h o t e r i c O x i d e s < / h 5 > < p > O x i d e s r e a c t i n g w i t h a c i d s < s t r o n g > a n d < / s t r o n g > b a s e s , e . g . .</p></li><li><p>Neutralisation already noted above.</p></li></ol><h5 id="273a9e87-a7cc-452a-a3aa-45cafef39a78" data-toc-id="273a9e87-a7cc-452a-a3aa-45cafef39a78" collapsed="false" seolevelmigrated="true">Amphoteric Oxides</h5><p>Oxides reacting with acids <strong>and</strong> bases, e.g. . < / p >< / l i >< l i >< p > N e u t r a l i s a t i o na l re a d y n o t e d ab o v e . < / p >< / l i >< / o l >< h 5 i d = "273 a 9 e 87 − a 7 cc − 452 a − a 3 aa − 45 c a f e f 39 a 78" d a t a − t oc − i d = "273 a 9 e 87 − a 7 cc − 452 a − a 3 aa − 45 c a f e f 39 a 78" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > A m p h o t er i c O x i d es < / h 5 >< p > O x i d esre a c t in g w i t ha c i d s < s t ro n g > an d < / s t ro n g > ba ses , e . g . 2O 3},\; \text{ZnO}.< / p > < h 5 i d = " e c b a 7 e 48 − e 494 − 4809 − a 555 − 714 b 6 f d d e c 7 f " d a t a − t o c − i d = " e c b a 7 e 48 − e 494 − 4809 − a 555 − 714 b 6 f d d e c 7 f " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > U s e s o f B a s e s < / h 5 > < p > • </p><h5 id="ecba7e48-e494-4809-a555-714b6fddec7f" data-toc-id="ecba7e48-e494-4809-a555-714b6fddec7f" collapsed="false" seolevelmigrated="true">Uses of Bases</h5><p>• < / p >< h 5 i d = " ec ba 7 e 48 − e 494 − 4809 − a 555 − 714 b 6 fdd ec 7 f " d a t a − t oc − i d = " ec ba 7 e 48 − e 494 − 4809 − a 555 − 714 b 6 fdd ec 7 f " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > U seso f B a ses < / h 5 >< p > • – s o a p s , p a p e r , r a y o n . < b r > • – soaps, paper, rayon. <br>• – so a p s , p a p er , r a yo n . < b r > • 2– m a n u f a c t u r e o f b l e a c h i n g p o w d e r . • – manufacture of bleaching powder. • – man u f a c t u reo f b l e a c hin g p o w d er .• 2– a n t a c i d . < b r > • – antacid. <br>• – an t a c i d . < b r > • 2CO 3}– w a s h i n g s o d a , w a t e r s o f t e n i n g . < b r > • – washing soda, water softening. <br>• – w a s hin g so d a , w a t erso f t e nin g . < b r > • – b a k i n g , f i r e e x t i n g u i s h e r s . < / p > < d i v d a t a − t y p e = " h o r i z o n t a l R u l e " > < h r > < / d i v > < h 4 i d = " 23 c 80 c 96 − 3 c 3 e − 433 f − 84 a 8 − f 671 b c f 08 e f 1 " d a t a − t o c − i d = " 23 c 80 c 96 − 3 c 3 e − 433 f − 84 a 8 − f 671 b c f 08 e f 1 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > p H C o n c e p t < / h 4 > < h 5 i d = " a 45 a 658 a − 2 b 3 f − 4337 − 8938 − 8 f 1 e e 6616 b 32 " d a t a − t o c − i d = " a 45 a 658 a − 2 b 3 f − 4337 − 8938 − 8 f 1 e e 6616 b 32 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > S c a l e < / h 5 > < p > 0 ( s t r o n g l y a c i d i c ) → 7 ( n e u t r a l ) → 14 ( s t r o n g l y b a s i c ) . – baking, fire extinguishers.</p><div data-type="horizontalRule"><hr></div><h4 id="23c80c96-3c3e-433f-84a8-f671bcf08ef1" data-toc-id="23c80c96-3c3e-433f-84a8-f671bcf08ef1" collapsed="false" seolevelmigrated="true">pH Concept</h4><h5 id="a45a658a-2b3f-4337-8938-8f1ee6616b32" data-toc-id="a45a658a-2b3f-4337-8938-8f1ee6616b32" collapsed="false" seolevelmigrated="true">Scale</h5><p>0 (strongly acidic) → 7 (neutral) → 14 (strongly basic). – bakin g , f i ree x t in gu i s h ers . < / p >< d i v d a t a − t y p e = " h or i zo n t a lR u l e " >< h r >< / d i v >< h 4 i d = "23 c 80 c 96 − 3 c 3 e − 433 f − 84 a 8 − f 671 b c f 08 e f 1" d a t a − t oc − i d = "23 c 80 c 96 − 3 c 3 e − 433 f − 84 a 8 − f 671 b c f 08 e f 1" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > p H C o n ce pt < / h 4 >< h 5 i d = " a 45 a 658 a − 2 b 3 f − 4337 − 8938 − 8 f 1 ee 6616 b 32" d a t a − t oc − i d = " a 45 a 658 a − 2 b 3 f − 4337 − 8938 − 8 f 1 ee 6616 b 32" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > S c a l e < / h 5 >< p > 0 ( s t ro n g l y a c i d i c ) → 7 ( n e u t r a l ) → 14 ( s t ro n g l y ba s i c ) . ; h i g h e r ; higher ; hi g h er
Colour Chart (Universal Indicator) 0: dark red; 4: orange; 7: green; 10: blue; 14: violet.
Practical Benchmarks • Gastric juice pH ≈ 1–2; rainwater <5.6 → acid rain. 2, , , 3) n e u t r a l i s e e x c e s s s t o m a c h a c i d . < b r > • B e e / a n t s t i n g i n j e c t s m e t h a n o i c a c i d ; r e l i e v e d b y m i l d b a s e ( b a k i n g − s o d a p a s t e ) . < / p > < p > D i l u t i o n o f a n a c i d l o w e r s ) neutralise excess stomach acid. <br>• Bee/ant sting injects methanoic acid; relieved by mild base (baking-soda paste).</p><p>Dilution of an acid lowers ) n e u t r a l i see x cesss t o ma c ha c i d . < b r > • B ee / an t s t in g inj ec t s m e t han o i c a c i d ; re l i e v e d b y mi l d ba se ( bakin g − so d a p a s t e ) . < / p >< p > D i l u t i o n o f ana c i d l o w ers → p H r i s e s ; d i s s o l v i n g m o r e b a s e i n c r e a s e s → pH rises; dissolving more base increases → p Hr i ses ; d i sso l v in g m ore ba se in cre a ses . < / p > < d i v d a t a − t y p e = " h o r i z o n t a l R u l e " > < h r > < / d i v > < h 4 i d = " a 8063309 − d 693 − 4 a 32 − b 394 − e 28 e c 858 d 0 f b " d a t a − t o c − i d = " a 8063309 − d 693 − 4 a 32 − b 394 − e 28 e c 858 d 0 f b " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > S a l t s < / h 4 > < h 5 i d = " 2 c 70 e 685 − 0245 − 4 c 52 − 9 b 67 − c 19 a e 8698567 " d a t a − t o c − i d = " 2 c 70 e 685 − 0245 − 4 c 52 − 9 b 67 − c 19 a e 8698567 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > D e f i n i t i o n a n d N o m e n c l a t u r e < / h 5 > < p > R e p l a c e m e n t o f a c i d h y d r o g e n b y m e t a l f o r m s s a l t . N a m e ’ s f i r s t p a r t f r o m b a s e ( m e t a l ) , s e c o n d f r o m a c i d r a d i c a l ( a n i o n ) . E x a m p l e : .</p><div data-type="horizontalRule"><hr></div><h4 id="a8063309-d693-4a32-b394-e28ec858d0fb" data-toc-id="a8063309-d693-4a32-b394-e28ec858d0fb" collapsed="false" seolevelmigrated="true">Salts</h4><h5 id="2c70e685-0245-4c52-9b67-c19ae8698567" data-toc-id="2c70e685-0245-4c52-9b67-c19ae8698567" collapsed="false" seolevelmigrated="true">Definition and Nomenclature</h5><p>Replacement of acid hydrogen by metal forms salt. Name’s first part from base (metal), second from acid radical (anion). Example: . < / p >< d i v d a t a − t y p e = " h or i zo n t a lR u l e " >< h r >< / d i v >< h 4 i d = " a 8063309 − d 693 − 4 a 32 − b 394 − e 28 ec 858 d 0 f b " d a t a − t oc − i d = " a 8063309 − d 693 − 4 a 32 − b 394 − e 28 ec 858 d 0 f b " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > S a lt s < / h 4 >< h 5 i d = "2 c 70 e 685 − 0245 − 4 c 52 − 9 b 67 − c 19 a e 8698567" d a t a − t oc − i d = "2 c 70 e 685 − 0245 − 4 c 52 − 9 b 67 − c 19 a e 8698567" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > De f ini t i o nan d N o m e n c l a t u re < / h 5 >< p > R e pl a ce m e n t o f a c i d h y d ro g e nb y m e t a l f or m ss a lt . N am e ’ s f i rs tp a r t f ro mba se ( m e t a l ) , seco n df ro ma c i d r a d i c a l ( ani o n ) . E x am pl e : – s o d i u m ( f r o m b a s e ) c h l o r i d e ( f r o m a c i d ) . < / p > < h 5 i d = " 4 e 6 f 0 c 29 − 91 d 8 − 4 f 8 f − 960 e − 9 b 482 e 15 f 026 " d a t a − t o c − i d = " 4 e 6 f 0 c 29 − 91 d 8 − 4 f 8 f − 960 e − 9 b 482 e 15 f 026 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > F a m i l i e s < / h 5 > < p > S a l t s s h a r i n g s a m e c a t i o n ( o r a n i o n ) b e l o n g t o o n e f a m i l y , e . g . s o d i u m s a l t s : – sodium (from base) chloride (from acid).</p><h5 id="4e6f0c29-91d8-4f8f-960e-9b482e15f026" data-toc-id="4e6f0c29-91d8-4f8f-960e-9b482e15f026" collapsed="false" seolevelmigrated="true">Families</h5><p>Salts sharing same cation (or anion) belong to one family, e.g. sodium salts: – so d i u m ( f ro mba se ) c h l or i d e ( f ro ma c i d ) . < / p >< h 5 i d = "4 e 6 f 0 c 29 − 91 d 8 − 4 f 8 f − 960 e − 9 b 482 e 15 f 026" d a t a − t oc − i d = "4 e 6 f 0 c 29 − 91 d 8 − 4 f 8 f − 960 e − 9 b 482 e 15 f 026" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > F ami l i es < / h 5 >< p > S a lt ss ha r in g s am ec a t i o n ( or ani o n ) b e l o n g t oo n e f ami l y , e . g . so d i u m s a lt s : 2\text{SO} 4. < / p > < h 5 i d = " d 61 d 9 d 7 e − 3 c f f − 4160 − a a 0 b − 309 a d 9296 a c 2 " d a t a − t o c − i d = " d 61 d 9 d 7 e − 3 c f f − 4160 − a a 0 b − 309 a d 9296 a c 2 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > C a t e g o r i e s < / h 5 > < o l > < l i > < p > < s t r o n g > N e u t r a l s a l t s < / s t r o n g > ( s t r o n g a c i d + s t r o n g b a s e ) – .</p><h5 id="d61d9d7e-3cff-4160-aa0b-309ad9296ac2" data-toc-id="d61d9d7e-3cff-4160-aa0b-309ad9296ac2" collapsed="false" seolevelmigrated="true">Categories</h5><ol><li><p><strong>Neutral salts</strong> (strong acid + strong base) – . < / p >< h 5 i d = " d 61 d 9 d 7 e − 3 c ff − 4160 − aa 0 b − 309 a d 9296 a c 2" d a t a − t oc − i d = " d 61 d 9 d 7 e − 3 c ff − 4160 − aa 0 b − 309 a d 9296 a c 2" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > C a t e g or i es < / h 5 >< o l >< l i >< p >< s t ro n g > N e u t r a l s a lt s < / s t ro n g > ( s t ro n g a c i d + s t ro n g ba se ) – , , , . < / p > < / l i > < l i > < p > < s t r o n g > A c i d i c s a l t s < / s t r o n g > ( s t r o n g a c i d + w e a k b a s e ) – .</p></li><li><p><strong>Acidic salts</strong> (strong acid + weak base) – . < / p >< / l i >< l i >< p >< s t ro n g > A c i d i cs a lt s < / s t ro n g > ( s t ro n g a c i d + w e akba se ) – 4\text{Cl}, , , 4. < / p > < / l i > < l i > < p > < s t r o n g > B a s i c s a l t s < / s t r o n g > ( w e a k a c i d + s t r o n g b a s e ) – .</p></li><li><p><strong>Basic salts</strong> (weak acid + strong base) – . < / p >< / l i >< l i >< p >< s t ro n g > B a s i cs a lt s < / s t ro n g > ( w e aka c i d + s t ro n g ba se ) – 2CO 3}, , ,
Universal Indicator Colours for Water & Salts Distilled water gives green (pH 7). Neutral salt solutions likewise.
Sodium Chloride (Common Salt) • Formula \text{NaCl}; obtained from sea-water & rock-salt deposits (brown due to impurities). 2,\; \text{H} 2. < / p > < h 5 i d = " 9 a d 8 c 27 a − b 7 e 7 − 4454 − a 524 − 436 c 9 b 2886 f a " d a t a − t o c − i d = " 9 a d 8 c 27 a − b 7 e 7 − 4454 − a 524 − 436 c 9 b 2886 f a " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > C h l o r − A l k a l i E l e c t r o l y s i s < / h 5 > < p > .</p><h5 id="9ad8c27a-b7e7-4454-a524-436c9b2886fa" data-toc-id="9ad8c27a-b7e7-4454-a524-436c9b2886fa" collapsed="false" seolevelmigrated="true">Chlor-Alkali Electrolysis</h5><p> . < / p >< h 5 i d = "9 a d 8 c 27 a − b 7 e 7 − 4454 − a 524 − 436 c 9 b 2886 f a " d a t a − t oc − i d = "9 a d 8 c 27 a − b 7 e 7 − 4454 − a 524 − 436 c 9 b 2886 f a " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > C h l or − A l ka l i El ec t ro l ys i s < / h 5 >< p > {(aq)} + 2H 2O \xrightarrow{\text{electricity}} 2NaOH{(aq)} + Cl 2\uparrow + H2\uparrow}P r o d u c t s a n d k e y u s e s : • Products and key uses: • P ro d u c t s an d k ey u ses : • – s o a p s , p a p e r , f i b r e s , d e g r e a s i n g . • – soaps, paper, fibres, degreasing. • – so a p s , p a p er , f ib res , d e g re a s in g .• 2– d r i n k i n g − w a t e r s t e r i l i s a t i o n , P V C , C F C s , p e s t i c i d e s , b l e a c h i n g p o w d e r . < b r > • – drinking-water sterilisation, PVC, CFCs, pesticides, bleaching powder. <br>• – d r inkin g − w a t ers t er i l i s a t i o n , P V C , CFC s , p es t i c i d es , b l e a c hin g p o w d er . < b r > • – a m m o n i a s y n t h e s i s , h y d r o g e n a t i o n o f o i l s , r o c k e t f u e l . < / p > < d i v d a t a − t y p e = " h o r i z o n t a l R u l e " > < h r > < / d i v > < h 4 i d = " 4771 b e 81 − 7676 − 40 f 0 − 9 f d b − d 8 c e 6 e 75 c f d 9 " d a t a − t o c − i d = " 4771 b e 81 − 7676 − 40 f 0 − 9 f d b − d 8 c e 6 e 75 c f d 9 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > D e r i v e d S a l t s a n d T h e i r C h e m i s t r y < / h 4 > < h 5 i d = " 2549 b b 6 d − e d 62 − 4061 − 8 a 5 c − e e 6 f 63 c 99 b 05 " d a t a − t o c − i d = " 2549 b b 6 d − e d 62 − 4061 − 8 a 5 c − e e 6 f 63 c 99 b 05 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > 1. B l e a c h i n g P o w d e r < / h 5 > < p > • C a l c i u m o x y c h l o r i d e – ammonia synthesis, hydrogenation of oils, rocket fuel.</p><div data-type="horizontalRule"><hr></div><h4 id="4771be81-7676-40f0-9fdb-d8ce6e75cfd9" data-toc-id="4771be81-7676-40f0-9fdb-d8ce6e75cfd9" collapsed="false" seolevelmigrated="true">Derived Salts and Their Chemistry</h4><h5 id="2549bb6d-ed62-4061-8a5c-ee6f63c99b05" data-toc-id="2549bb6d-ed62-4061-8a5c-ee6f63c99b05" collapsed="false" seolevelmigrated="true">1. Bleaching Powder</h5><p>• Calcium oxychloride – amm o nia sy n t h es i s , h y d ro g e na t i o n o f o i l s , roc k e t f u e l . < / p >< d i v d a t a − t y p e = " h or i zo n t a lR u l e " >< h r >< / d i v >< h 4 i d = "4771 b e 81 − 7676 − 40 f 0 − 9 fd b − d 8 ce 6 e 75 c fd 9" d a t a − t oc − i d = "4771 b e 81 − 7676 − 40 f 0 − 9 fd b − d 8 ce 6 e 75 c fd 9" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > Der i v e d S a lt s an d T h e i r C h e mi s t ry < / h 4 >< h 5 i d = "2549 bb 6 d − e d 62 − 4061 − 8 a 5 c − ee 6 f 63 c 99 b 05" d a t a − t oc − i d = "2549 bb 6 d − e d 62 − 4061 − 8 a 5 c − ee 6 f 63 c 99 b 05" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > 1. Bl e a c hin g P o w d er < / h 5 >< p > • C a l c i u m o x yc h l or i d e 2}; p r e p a r e d b y ; prepared by ; p re p a re d b y 2 + Cl_2.< b r > • S m e l l s o f c h l o r i n e ; l i m i t e d s o l u b i l i t y . U s e s : t e x t i l e / p a p e r b l e a c h i n g , d i s i n f e c t a n t , C H C l 3 m a n u f a c t u r e . < / p > < h 5 i d = " 5448169 b − 89 b 4 − 40 a d − 8 c f 6 − 9 e 236 f d 70 c 33 " d a t a − t o c − i d = " 5448169 b − 89 b 4 − 40 a d − 8 c f 6 − 9 e 236 f d 70 c 33 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > 2. W a s h i n g S o d a < / h 5 > < p > • S o d i u m c a r b o n a t e d e c a h y d r a t e <br>• Smells of chlorine; limited solubility. Uses: textile/paper bleaching, disinfectant, CHCl₃ manufacture.</p><h5 id="5448169b-89b4-40ad-8cf6-9e236fd70c33" data-toc-id="5448169b-89b4-40ad-8cf6-9e236fd70c33" collapsed="false" seolevelmigrated="true">2. Washing Soda</h5><p>• Sodium carbonate decahydrate < b r > • S m e ll so f c h l or in e ; l imi t e d so l u bi l i t y . U ses : t e x t i l e / p a p er b l e a c hin g , d i s in f ec t an t , C H C l 3 man u f a c t u re . < / p >< h 5 i d = "5448169 b − 89 b 4 − 40 a d − 8 c f 6 − 9 e 236 fd 70 c 33" d a t a − t oc − i d = "5448169 b − 89 b 4 − 40 a d − 8 c f 6 − 9 e 236 fd 70 c 33" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > 2. Wa s hin g S o d a < / h 5 >< p > • S o d i u m c a r b o na t e d ec ah y d r a t e 2CO 3·10H2O}; o b t a i n e d v i a < / e m > < s t r o n g > < e m > S o l v a y p r o c e s s < / e m > < / s t r o n g > < e m > f r o m b r i n e , ; obtained via </em><strong><em>Solvay process</em></strong><em> from brine, ; o b t ain e d v ia < / e m >< s t ro n g >< e m > S o l v a y p rocess < / e m >< / s t ro n g >< e m > f ro mb r in e , 3, , , 2. • U p o n h e a t i n g , . • Upon heating, .• U p o nh e a t in g , 2CO3·10H 2O \rightarrow Na2CO 3 + 10H_2O}. < b r > • B a s i c s a l t ( h y d r o l y s e s t o . <br>• Basic salt (hydrolyses to . < b r > • B a s i cs a lt ( h y d ro l yses t o ) . U s e s : w a t e r − s o f t e n i n g , g l a s s , s o a p s / d e t e r g e n t s , p a p e r . < / p > < h 5 i d = " 2 e d c a a c e − 6 e 0 f − 4 d f 0 − 8 b 76 − d e e e b 32 b 4 d 0 d " d a t a − t o c − i d = " 2 e d c a a c e − 6 e 0 f − 4 d f 0 − 8 b 76 − d e e e b 32 b 4 d 0 d " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > 3. B a k i n g S o d a / B a k i n g P o w d e r < / h 5 > < p > • S o d i u m h y d r o g e n c a r b o n a t e ). Uses: water-softening, glass, soaps/detergents, paper.</p><h5 id="2edcaace-6e0f-4df0-8b76-deeeb32b4d0d" data-toc-id="2edcaace-6e0f-4df0-8b76-deeeb32b4d0d" collapsed="false" seolevelmigrated="true">3. Baking Soda / Baking Powder</h5><p>• Sodium hydrogencarbonate ) . U ses : w a t er − so f t e nin g , g l a ss , so a p s / d e t er g e n t s , p a p er . < / p >< h 5 i d = "2 e d c aa ce − 6 e 0 f − 4 df 0 − 8 b 76 − d eee b 32 b 4 d 0 d " d a t a − t oc − i d = "2 e d c aa ce − 6 e 0 f − 4 df 0 − 8 b 76 − d eee b 32 b 4 d 0 d " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > 3. B akin g S o d a / B akin g P o w d er < / h 5 >< p > • S o d i u mh y d ro g e n c a r b o na t e 3. • P r e p a r e d b y p a s s i n g . • Prepared by passing .• P re p a re d b y p a ss in g 2t h r o u g h c o n c e n t r a t e d b r i n e s a t u r a t e d w i t h through concentrated brine saturated with t h ro ug h co n ce n t r a t e d b r in es a t u r a t e d w i t h 3( i n t e r m e d i a t e i n S o l v a y ) . • O n h e a t i n g : (intermediate in Solvay). • On heating: ( in t er m e d ia t e in S o l v a y ) .• O nh e a t in g : 3 \rightarrow Na2CO 3 + CO2 + H 2O}– – – 2l e a v e n s c a k e , e x t i n g u i s h e r g a s . • B a k i n g p o w d e r = leavens cake, extinguisher gas. • Baking powder = l e a v e n sc ak e , e x t in gu i s h er g a s .• B akin g p o w d er = 3+ m i l d a c i d ( t a r t a r i c ) t o n e u t r a l i s e b i t t e r + mild acid (tartaric) to neutralise bitter + mi l d a c i d ( t a r t a r i c ) t o n e u t r a l i se bi tt er 2CO 3}. < / p > < h 5 i d = " 82163 b 2 d − c 113 − 4986 − 9062 − 3 c e 569 e b 71 e 9 " d a t a − t o c − i d = " 82163 b 2 d − c 113 − 4986 − 9062 − 3 c e 569 e b 71 e 9 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > 4. P l a s t e r o f P a r i s ( P O P ) < / h 5 > < p > • C a l c i u m s u l p h a t e h e m i h y d r a t e .</p><h5 id="82163b2d-c113-4986-9062-3ce569eb71e9" data-toc-id="82163b2d-c113-4986-9062-3ce569eb71e9" collapsed="false" seolevelmigrated="true">4. Plaster of Paris (POP)</h5><p>• Calcium sulphate hemihydrate . < / p >< h 5 i d = "82163 b 2 d − c 113 − 4986 − 9062 − 3 ce 569 e b 71 e 9" d a t a − t oc − i d = "82163 b 2 d − c 113 − 4986 − 9062 − 3 ce 569 e b 71 e 9" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > 4. Pl a s t ero f P a r i s ( POP ) < / h 5 >< p > • C a l c i u m s u lp ha t e h e mih y d r a t e 4·\tfrac12 H 2O, p r o d u c e d b y h e a t i n g g y p s u m , produced by heating gypsum , p ro d u ce d b y h e a t in gg y p s u m 4·2H 2Ot o to t o . < b r > • S e t s t o h a r d g y p s u m w h e n m o i s t e n e d : . <br>• Sets to hard gypsum when moistened: . < b r > • S e t s t o ha r d g y p s u m w h e nm o i s t e n e d : 4·\tfrac12 H 2O + \tfrac32 H2O \rightarrow CaSO 4·2H_2O}. < b r > • U s e s : c a s t s f o r f r a c t u r e s , m o u l d s , c h a l k , f i r e − p r o o f i n g . S t o r e d i n a i r t i g h t c o n t a i n e r s t o p r e v e n t p r e m a t u r e s e t t i n g . < / p > < h 5 i d = " b a 0 f 2340 − 2 f d 2 − 4692 − 998 a − d b f 707 f 568 e d " d a t a − t o c − i d = " b a 0 f 2340 − 2 f d 2 − 4692 − 998 a − d b f 707 f 568 e d " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > 5. W a t e r o f C r y s t a l l i s a t i o n < / h 5 > < p > F i x e d w a t e r m o l e c u l e s i n t e g r a l t o c r y s t a l l a t t i c e ; t h e i r l o s s c h a n g e s c o l o u r / t e x t u r e . < b r > E x a m p l e s : < b r > • . <br>• Uses: casts for fractures, moulds, chalk, fire-proofing. Stored in airtight containers to prevent premature setting.</p><h5 id="ba0f2340-2fd2-4692-998a-dbf707f568ed" data-toc-id="ba0f2340-2fd2-4692-998a-dbf707f568ed" collapsed="false" seolevelmigrated="true">5. Water of Crystallisation</h5><p>Fixed water molecules integral to crystal lattice; their loss changes colour/texture. <br>Examples: <br>• . < b r > • U ses : c a s t s f or f r a c t u res , m o u l d s , c ha l k , f i re − p roo f in g . St ore d inai r t i g h t co n t ain ers t o p re v e n tp re ma t u rese tt in g . < / p >< h 5 i d = " ba 0 f 2340 − 2 fd 2 − 4692 − 998 a − d b f 707 f 568 e d " d a t a − t oc − i d = " ba 0 f 2340 − 2 fd 2 − 4692 − 998 a − d b f 707 f 568 e d " co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > 5. Wa t ero f C rys t a ll i s a t i o n < / h 5 >< p > F i x e d w a t er m o l ec u l es in t e g r a lt ocrys t a ll a tt i ce ; t h e i r l ossc han g esco l o u r / t e x t u re . < b r > E x am pl es :< b r > • 4·5H 2O( b l u e ) → (blue) → ( b l u e ) → 4( w h i t e ) o n h e a t i n g . • (white) on heating. • ( w hi t e ) o nh e a t in g .• 2SO}4·10H 2O – Glauber’s salt.
Representative Laboratory & Safety Notes • Test for \text{H}_2< / s t r o n g > – f l a m i n g s p l i n t n e a r g a s p r o d u c e s s h a r p ‘ p o p ’ . < b r > • < s t r o n g > A c i d + m e t a l c a r b o n a t e < / s t r o n g > – o b s e r v e e f f e r v e s c e n c e ; p a s s g a s t o l i m e − w a t e r . < b r > • < s t r o n g > D r y </strong> – flaming splint near gas produces sharp ‘pop’. <br>• <strong>Acid + metal carbonate</strong> – observe effervescence; pass gas to lime-water. <br>• <strong>Dry < / s t ro n g > – f l amin g s pl in t n e a r g a s p ro d u cess ha r p ‘ p o p ’. < b r > • < s t ro n g > A c i d + m e t a l c a r b o na t e < / s t ro n g > – o b ser v ee ff er v esce n ce ; p a ss g a s t o l im e − w a t er . < b r > • < s t ro n g > Dry w i t h d r y l i t m u s < / s t r o n g > – n o c o l o u r c h a n g e ; a d d m o i s t u r e t o r e v e a l a c i d i t y . < / p > < d i v d a t a − t y p e = " h o r i z o n t a l R u l e " > < h r > < / d i v > < h 4 i d = " 13 b 6 e d 99 − 6 e 07 − 4 b 63 − a d 53 − 2828 e 6 a c 9 f e 6 " d a t a − t o c − i d = " 13 b 6 e d 99 − 6 e 07 − 4 b 63 − a d 53 − 2828 e 6 a c 9 f e 6 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > N C E R T C o n c e p t H i g h l i g h t s ( C o n d e n s e d ) < / h 4 > < p > • I d e n t i f i c a t i o n o f a c i d / b a s e / n e u t r a l w i t h s i n g l e c o l o u r e d − l i t m u s s t r a t e g y . < b r > • C u r d i n C u / B r a s s y i e l d s t o x i c s a l t s – a v o i d . < b r > • D i l u t i o n m u s t b e a c i d → w a t e r . < b r > • D i s t i l l e d w a t e r n o n − c o n d u c t i v e ; r a i n w a t e r c o n d u c t i v e ( d i s s o l v e d a c i d s ) . < b r > • B a s i c s o l u t i o n s s t i l l c o n t a i n with dry litmus</strong> – no colour change; add moisture to reveal acidity.</p><div data-type="horizontalRule"><hr></div><h4 id="13b6ed99-6e07-4b63-ad53-2828e6ac9fe6" data-toc-id="13b6ed99-6e07-4b63-ad53-2828e6ac9fe6" collapsed="false" seolevelmigrated="true">NCERT Concept Highlights (Condensed)</h4><p>• Identification of acid/base/neutral with single coloured-litmus strategy. <br>• Curd in Cu/Brass yields toxic salts – avoid. <br>• Dilution must be acid → water. <br>• Distilled water non-conductive; rain water conductive (dissolved acids). <br>• Basic solutions still contain w i t h d ry l i t m u s < / s t ro n g > – n oco l o u rc han g e ; a dd m o i s t u re t ore v e a l a c i d i t y . < / p >< d i v d a t a − t y p e = " h or i zo n t a lR u l e " >< h r >< / d i v >< h 4 i d = "13 b 6 e d 99 − 6 e 07 − 4 b 63 − a d 53 − 2828 e 6 a c 9 f e 6" d a t a − t oc − i d = "13 b 6 e d 99 − 6 e 07 − 4 b 63 − a d 53 − 2828 e 6 a c 9 f e 6" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > NCERTC o n ce pt H i g h l i g h t s ( C o n d e n se d ) < / h 4 >< p > • I d e n t i f i c a t i o n o f a c i d / ba se / n e u t r a lw i t h s in g l eco l o u re d − l i t m u ss t r a t e g y . < b r > • C u r d in C u / B r a ssy i e l d s t o x i cs a lt s – a v o i d . < b r > • D i l u t i o nm u s t b e a c i d → w a t er . < b r > • D i s t i ll e d w a t er n o n − co n d u c t i v e ; r ain w a t erco n d u c t i v e ( d i sso l v e d a c i d s ) . < b r > • B a s i cso l u t i o n ss t i ll co n t ain ; a c i d – b a s e n a t u r e d e p e n d s o n r e l a t i v e ; acid–base nature depends on relative ; a c i d – ba se na t u re d e p e n d so n re l a t i v e v s vs v s . < / p > < p > S a m p l e n u m e r i c a l : I f .</p><p>Sample numerical: If . < / p >< p > S am pl e n u m er i c a l : I f N a O H n e u t r a l i s e s NaOH neutralises N a O H n e u t r a l i ses H C l , t h e n HCl, then H Cl , t h e n N a O H n e e d s NaOH needs N a O H n ee d s
Ethical, Environmental & Practical Aspects • Acid rain (pH <5.6) corrodes monuments, harms biota. 2SO 4}, , , ) a l t e r s s o i l p H . < b r > • P r o p e r d i s p o s a l o f l a b o r a t o r y a c i d s / b a s e s p r e v e n t s a q u a t i c p H s h o c k . < / p > < d i v d a t a − t y p e = " h o r i z o n t a l R u l e " > < h r > < / d i v > < h 4 i d = " 700 a 3597 − c 2 a c − 4 f b f − 91 b b − 98 e 57859 f 119 " d a t a − t o c − i d = " 700 a 3597 − c 2 a c − 4 f b f − 91 b b − 98 e 57859 f 119 " c o l l a p s e d = " f a l s e " s e o l e v e l m i g r a t e d = " t r u e " > Q u i c k R e f e r e n c e – F o r m u l a e o f C o m m o n S a l t s < / h 4 > < p > ) alters soil pH. <br>• Proper disposal of laboratory acids/bases prevents aquatic pH shock.</p><div data-type="horizontalRule"><hr></div><h4 id="700a3597-c2ac-4fbf-91bb-98e57859f119" data-toc-id="700a3597-c2ac-4fbf-91bb-98e57859f119" collapsed="false" seolevelmigrated="true">Quick Reference – Formulae of Common Salts</h4><p> ) a lt ersso i lp H . < b r > • P ro p er d i s p os a l o f l ab or a t ory a c i d s / ba ses p re v e n t s a q u a t i c p Hs h oc k . < / p >< d i v d a t a − t y p e = " h or i zo n t a lR u l e " >< h r >< / d i v >< h 4 i d = "700 a 3597 − c 2 a c − 4 f b f − 91 bb − 98 e 57859 f 119" d a t a − t oc − i d = "700 a 3597 − c 2 a c − 4 f b f − 91 bb − 98 e 57859 f 119" co ll a p se d = " f a l se " seo l e v e l mi g r a t e d = " t r u e " > Q u i c k R e f ere n ce – F or m u l a eo f C o mm o n S a lt s < / h 4 >< p > 2} \ \text{Magnesium chloride} &:& \text{MgCl 2} \2} \ \text{Sodium sulphate} &:& \text{Na 2SO4} \ \text{Potassium nitrate} &:& \text{KNO 3} \3} \ \text{Copper sulphate} &:& \text{CuSO 4} \
Concluding Insights Understanding acids, bases and salts links taste, industrial synthesis, environmental chemistry and biological health. The pH scale provides a universal language connecting ion concentration to real-world phenomena—from tooth decay to rocket fuel. Mastery of indicator behaviour, reaction patterns and safe-handling principles is indispensable for both examinations and practical laboratory competence.