Chemical changes when matter ineract

hydrochloric acids

HCl

sulfirc acid

H2SO4

nitric acid

HNO3

physical properties of acid

sour taste

corrosive

soluble in water

turns blue lithmus paper red

pH value less than 7

sodium hydroxide

NaOH

Potassium hydroxide

KOH

Calcium hydroxide

Ca(OH)2

aqueos ammonia

NH3

physical properties of alkali

bitter taste

soapy filling

corrosive

soluble in water

turns red lithmus paper blue

pH value greater than 7

indicator

substance that changes colour due to how acidic or alkaline a solution is

examples of indicators

lithmus paper

Universal Indicator

Methyl orange

why indicator commonly choosen

easy to use

gives rapid observation

reaction of Lithmus paper

acid- red

alakali- blue

Univeral Indicator reaction

acid- red orange yellow

alkali- blue purple

Methyl orange

acid- red

alkali- yellow

advantages of Universal Indicator

diffrentiate strong and weak acids

determine pH value using colour chart

pH scale

measure of how acidic or alkaline solution is

scale from 0-14

pH neutral

ph 7

equal concentration of hydrogen and hydroxide ions

pH acid

lesser than 7

smaller pH, more acidic

higher concentration of hydrogen

pH alkali

pH value more than 7

larger pH, more alkaline

higher concentration of hydroxide (OH-)

Advantages of using pH meter over indicator

more precise measurement

allows monitering of pH values over time

reading will not be affected by color of solution

what can be observed when acid reacts with metal

efferverscence seen/ bubbles of gas produced

test tube ( bottom ) gets warmer

metal becomes smaller in size

change in colour

products of acid and metal reaction

acid + metal → salt + hydrogen

how to determine presence of hydrogen

test; place a lighted splint at the mouth of the test tube

result; if hydrogen is present, splint will extinguish with a' ‘pop’ sound

how to name salt formed

metal ion by non metal ion ( form acid )

e.g hydrochloric acid → (metal) chloride

which metals do not react with acids

gold, silver, copper