Question

Pearls are made of calcium carbonate and can be broken down ( or dissolved ) by Hcl according to the following balanced equation :

CaCo3 + 2 HCl -> CaCl2 + H2O + CO2

What volume of 0.400 M HCl would be needed to dissolve a CaCO3 pearl which weighs 0.400 grams?

Answer 1

$\boxed{\sf Molarity=\dfrac{Moles}{Vol\:in\:L}}$

Moles of CaCO_3:-

• 0.4/100=0.004mol

• 1 mol Calcium carbonate need 2 mol HCl
• 0.004 mol will need 0.004(2)=0.008mol HCl

Come to formula stated first

$\\ \tt\Rrightarrow Volume=\dfrac{Moles}{Molarity}$

$\\ \tt\Rrightarrow volume=\dfrac{0.008}{0.4}$

$\\ \tt\Rrightarrow volume=0.02\ell=20m\ell$