Regents Chemistry Exam August 2022

36. Given the equation representing a reaction:

2H2(g) + 2NO(g) → N2(g) + 2H2O(g)

What is the mass of N2(g) produced when 1.0 gram of H2(g) completely reacts with 15.0 grams of NO(g) to produce 9.0 grams of H2O(g)?

(1) 7.0 g

(2) 14.0 g

(3) 25.0 g

(4) 28.0 g

Explanation: The law of conservation of mass tells us that mass is neither created nor destroyed in a reaction. Therefore, the mass of products must equal to the mass of reactants. We have all the masses expect for nitrogen gas. Let's say x is the mass of nitrogen gas.

1g+ 15g = X + 9g

X=7g

Answer: 1