What type of substance reacts with limestone (caco3) and produces carbon dioxide gas?
a) a neutral substance
b)a base
c)an acid
d)both an acid and a base

Option C= an acid

CaCO₃ is a very wide spread compound, and is found in chalk, lime, marble etc. This substance plays a very important role for human beings, as calcium carbonate is also widely used in the food industry, as a natural white colorant. CaCO₃ is also used for the manufacture of paper and plastic, in construction, and in many other spheres.

Calcium carbonate is a white substance (solid crystals) in powder or solid form, which is capable of reacting with water, but does not completely dissolve in it. But When any acid is reacted with calcium carbonate, the salt of the anionic part of the acid with calcium is formed. And H2CO3 is formed which may later break down to H2O+CO2, hence net reaction will be,

2HCl + CaCO3 → CaCl2 + H2CO3  

H2CO3 → H2O (l) + CO2 (g)

When calcium carbonate reacts with sulfuric acid, it forms water, carbon dioxide and calcium sulfate.

1. CaCO3 (s) + H2SO4 (l) → H2CO3 (aq) + CaSO4 (s)

2. H2CO3 (aq) → H2O (l) + CO2 (g)

So…

CaCO3 (s) + H2SO4 (l) → H2O (l) + CO2 (g) + CaSO4 (s)

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o

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