Question

1. from a laboratory process designed to separate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. how much water was originally involved in the process?

Explanation:

Step1: Recall the law of conservation of mass

The mass of reactants equals the mass of products in a chemical reaction. Water is decomposed into hydrogen and oxygen.

Step2: Calculate the mass of water

The mass of water is the sum of the mass of hydrogen and oxygen collected. So, $m_{water}=m_{hydrogen}+m_{oxygen}$.
Substitute $m_{hydrogen} = 10.0\ g$ and $m_{oxygen}=79.4\ g$ into the formula: $m_{water}=10.0\ g + 79.4\ g=89.4\ g$.

Answer:

89.4 g