When 4.2 gram of sodium bicarbonate reacts with 10.0 g of acetic acid, the product contains 2.2 g of carbon dioxide and residue cxontaining water and Sodium acetate. The mass of the residue will be:- *

Na2CO3+2HCl⟶2NaCl+H2O+CO2

Law of conservation of mass- It states that for any closed system, the mass of the system always remain constant over time, as mass of system cannot change. Therefore, (mass of Na2CO3+ mass of HCl) should be equal to (mass of residue + mass of CO2)

Mass of Na2CO3=4.2 g

Mass of HCl=10 g

Mass of residue =12 g

Mass of CO2=2.2 g

∴ Mass of Na2CO3+ Mass of HCl=14.2 g

and Mass of residue + Mass of CO2=14.2 g

Therefore, they follow law of conservation of mass.