Under certain conditions, water can be separated into oxygen and hydrogen gases according to the equation 2H20 → 2H2 + O2.

Question

In a lab, 112 g of hydrogen gas and 888g of oxygen gas were collected. Student A says that the amount cannot be determined, but Student B says that the water must have been 1000g. Who is Correct?

(1 point)
Responses

Student B, because of the law of conservation of matter.
Student B, because of the law of conservation of matter.

Neither correct. It was 2,000g because the equation shows 2H2O.
Neither correct. It was 2,000g because the equation shows 2H 2 O.

Student A, because the water is not measured to start with.
Student A, because the water is not measured to start with.

Neither is correct. It would have Ben 1112 g, because there are 2H2 to 102

Answer 1

To determine the total mass of water that was decomposed into hydrogen and oxygen, we can use the law of conservation of mass, which states that mass is neither created nor destroyed in a chemical reaction.

Given that the student collected:

• 112 g of hydrogen gas (H₂)
• 888 g of oxygen gas (O₂)

First, we need to calculate the total mass of gases collected:

\[ \text{Total mass of gases} = \text{mass of } H_2 + \text{mass of } O_2 \] \[ \text{Total mass of gases} = 112 \text{ g} + 888 \text{ g} = 1000 \text{ g} \]

Since the reaction shows that water (H₂O) decomposes into hydrogen and oxygen gases with a total mass equal to the original mass of the water, we conclude that the total mass of the water that decomposed is 1000 g.

Thus, the correct response is:

Student B, because of the law of conservation of matter.