Question

Why should curd and sour substances not be kept in brass and copper
vessels?
Which gas is usually liberated when an acid reacts with a metal?
Illustrate with an example. How will you test for the presence of
this gas?
Metal compound A reacts with dilute hydrochloric acid to produce
effervescence. The gas evolved extinguishes a burning candle. Write a
balanced chemical equation for the reaction iſ one of the compounds
formed is calcium chloride.​

Answer 1

Answer:

1. curd and sour substances should not be kept in brass and copper because curd are acidic in nature which reacts with copper and brass

Answer 2

Answer:

1)when kept in copper or brass vessels,curd(and other acidic food items) reacts with copper and forms toxic compounds which may be unfit for human consumption,and may cause food poisoning. thus it is not advisable to keep curd and other acidic or sour food items in copper or brass vessels.

2)Hydrogen gas

A splint is lit and held near the opening of the tube, then the stopper is removed to expose the splint to the gas. If the gas is flammable, the mixture ignites. This test is most commonly used to identify hydrogen, which ignites with a distinctive 'squeaky pop' sound.

3)the metal compound A is calcium carbonate.

CaCO3+ HCl -> CaCl2 + CO2 + H2O.