chemistry ch 2 mistakes and important questions

answer a

answer a

answer b

you want to convert it to ppt so it appears on x-ray and also come out in the patient poop

ba ion form ppt with sodium and phosphate salt solution

answer C

answer b

• remeber that Co2 can’t be oxidized and sparingly solube and insolube is the same thing

(a) Another salt of the same acid: MgCO₃ is a salt of carbonic acid, the same acid that bicarbonate comes from. It is produced.

(b) A gas that oxidizes in air: The gas produced is CO₂. Carbon dioxide is already fully oxidized (carbon is in its highest oxidation state, +4), so it does not oxidize further in air. This is not produced, so it is the exception.

Both words describe the same thing here. In school chemistry, “insoluble” really means very slightly soluble. No ionic compound has a solubility of exactly zero, because a tiny amount of it always dissolves. MgCO₃ dissolves only to about 0.1 g per litre, so a textbook calls it “insoluble” while a more precise statement is “sparingly soluble.”

(c) A compound sparingly soluble in water: MgCO₃ is insoluble only slightly soluble in water, so it fit

sparingly means very little amount

(d) all carbonate and bicarbonate dissolve in acids and MgCO₃ is white ppt.

answer c

• AgNo3 will form white ppt. with Cl

• answer a

answer d

answer c

you need acidic medium of HCl

answer:

OH⁻

Ba²⁺

• the acid is H2So4 becuase of two thing

first he said the balance is one two one so HCl is not correct because the balance has to be 1 to 2

second he said the salt X is not affected by any acid so the anion has to be from the stable group(bacl2 group) either So4 or Po4 (we didn’t study Po4 also the balance doesn’t match)

so at the end the salt X is FeSO₄ which its cation is Fe²⁺ and anion SO₄²⁻

so you need to think which anion form perciptate with Fe²⁺ the answer is OH⁻ (because iron is from the 3rd analytic group)

and which cation form perciptate with SO₄²⁻ the answer is Ba²⁺ (because SO₄²⁻ is from the BaCl2 soultion which from perciptate with it

NaAlo2 is aq (solube in water) so it will break into ions as in the choices un like Fe(OH)3 is solid ppt. insolube in water

answer a

first cancel cl becuase it is in both and bacl can’t reacth with them becuase they have the same ion

A precipitate only forms when two ions in solution combine to make an insoluble compound. With NaCl, every possible new combination is soluble, so everything stays dissolved.

With ammonium carbonate, NaCl would form:

• Na₂CO₃ (sodium carbonate), which is soluble in water

• NH₄Cl (ammonium chloride), which is soluble in water

answer d

answer d

Acidified KMnO₄ is an oxidising agent used to detect reducing ions such as NO₂⁻, SO₃²⁻, S²⁻, S₂O₃²⁻ and reducing cations :Fe²⁺. It loses its violet colour when it reacts. It does not react with ions that are already at their highest oxidation state,

c is wrong becuase CaCo3 dissolve in dil HCl and water containg Co2

answer c

the anion has to be from the bacl2 group becuase it is not affected by any acid

answer b

you can solve it by equation

if two acids have the same M V then they have the same No.moles.

the second base need 3 moles while the first need 2 moles since the M is constant becuase it the same acid so the volume needed in the second is higher becuase M=mol/V so V increase by increasing mol at constant M

answer a

M=mol/v so it is inverse so if v incrsaed to doube M decrease to half and cancel each other

c

a

he said unkown SUBSTANCE but the concetration is the unkown not substance

remeber any salt that contain Na K NH₄ is soluble in water so it doesn’t form ppt at all