Question

In the reaction 2NaCl + 2H2O → 2NaOH + C12 + H2, the reactants should:

weigh more than the products because the reaction isn't perfect.
weigh less than the products because mass is lost.
weigh the same as the products.
weigh more because Cl2 and H2 are gases.

Answer 1

D

Step-by-step explanation:

Tough question. Both Cl2 and H2 are gases. Everything depends on what the water is. If it's a liquid, then D is the answer. If it's a gas, then you have to be a little more careful.

2H2O = 2 * 18 = 36.

Cl2 = 2*Cl = 2 * 35.5

Cl2 = 71

So D is still the answer.

Answer 2

Answer: weigh the same as the products.

Step-by-step explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

`2NaCl+2H_2O\rightarrow 2NaOH+Cl_2+H_2`

Given:

Mass of products = Mass of sodium hydroxide + mass of chlorine + mass of hydrogen = 2(40)+1(71)+2(1)= 153 g

Mass of reactants = Mass of sodium chloride + mass of water = 2(58.5)++2(18)= 153 g

Thus the total mass of reactants is equal to the total mass of products.