Question

Under certain conditions, water can be separated into oxygen and hydrogen gases according to the equation: 2H2O → 2H2 + O2 .

In a lab, 96g of hydrogen gas and 404g of oxygen gas were collected. Student A says that the starting amount of water cannot be determined, but Student B says that the water must have been 500g. Who is correct? (1 point)

A. Student A, because the water was not measured to start with.
B. Neither are correct. It would have been 1112g, because there are 2 H2 and 1 O2 .
C. Student B, because the law of conservation of matter.
D. Neither are correct. It was 2000g because the equation shows 2H2O .

Answer 1

To determine who is correct, we need to calculate the mass of water. Using the molar masses of hydrogen and oxygen, we can calculate that the water must have been 500g, so Student B is correct. The correct answer is option: C. Student B, because the law of conservation of matter.

Step-by-step explanation:

To determine who is correct, we need to calculate the mass of water. From the balanced equation, we know that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water.

Using the molar masses of hydrogen (2.02 g/mol) and oxygen (32.0 g/mol), we can calculate the mass of water produced:

2 x 2.02 g + 32.0 g = 36.04 g

Since the total mass of the collected gases is 96g of hydrogen and 404g of oxygen, the mass of water produced must be:

96g + 404g = 500g

Therefore, Student B is correct that the water must have been 500g based on the law of conservation of matter.