Question

In a chemical reaction, $100g$ baking soda mixture containing sodium bicarbonate and vinegar on heating gives $43g$ of carbon dioxide gas. What mass of solid residue is left in food?
(A) $54g$
(B) $55g$
(C) $56g$
(D) $57g$

Answer 1

In this question we have to apply the concept of law of conservation of mass which states that mass can neither be created nor be destroyed in a chemical reaction. According to the law of conservation of mass, the mass of the reactants must be equal to the mass of the products for a low energy in any thermodynamic process.

Complete step by step answer:
As we know, baking soda is chemically known as sodium bicarbonate with formula $NaHC{O_3}$. It is present as white solid crystalline fine powder. It is alkaline in nature and mild salty in taste. Sodium bicarbonate can be used to remove any acidic impurities from a crude liquid producing a pure sample.
i.e. $NaHC{O_3} + HCl \to NaCl + {H_2}C{O_3}$
Sodium bicarbonate is used in cooking green vegetables as it gives bright green colour. It is also used as a leavening agent in cooking. It can also be used to soften pulses before and during cooking. Baking soda in aqueous solution to treat heartburn and act as an antacid to treat acid indigestion. Sodium bicarbonate is also used to control fungal growth. It can also be used as a mild antiseptic and can also be used as a fire extinguisher. It is claimed that baking soda is an effective odor remover and it is accursed to keep an open base of baking in the refrigerator to absorb bad odor.
When a baking soda mixture containing sodium bicarbonate and vinegar is heated, it leads to the formation of solid residue with the evolution of carbon dioxide. Now according to the law of conservation of mass, we know that mass can neither be created nor distorted in a chemical reaction. This implies that the mass of the reactant should be equal to the mass of the product. So according to question, we get
${\text{Mass}}\;{\text{of}}\;{\text{Baking-soda}}\;{\text{mixture = }}\,{\text{Mass}}\;{\text{of}}\;{\text{Residue + Mass}}\;{\text{of}}\;{\text{carbon}}\;{\text{dioxide}}$
OR $Mass\;of\;solid\;\operatorname{Re} sidue = \left( {Mass\;of\;Baking-soda\;Mixture} \right) - Mass\;of\;Carbon\;dioxide - - - - \left( 1 \right)$
According to the question, the mass of baking soda mixture given is $100g$ and mass of carbon dioxide is $43g$ given. So putting value in Equation$\left( 1 \right)$, we get mass of
$Mass\;of\;{\text{Residue}} = 100 - 43 = 57g$
So option (D) is the correct answer.

Note:
Law of conservation of mass is mainly used in closed systems because in a closed system, the mass of gases can be found easily. If it occurs in an open system, the mass of gas escapes and it will be difficult to find out.