Question

in the combustion of hydrogen gas, hydrogen reacts with oxygen from the air to form water vapor.
hydrogen + oxygen —→ water
if you burn 33.5 g of hydrogen and produce 299 g of water, how much oxygen reacted?

Explanation:

Step1: Recall the law of conservation of mass

In a chemical reaction, the total mass of reactants equals the total mass of products. So, mass of hydrogen + mass of oxygen = mass of water.

Step2: Rearrange the formula to find mass of oxygen

Let \( m_{O_2} \) be the mass of oxygen. Then \( m_{O_2} = \text{mass of water} - \text{mass of hydrogen} \).
Substitute the given values: \( \text{mass of water} = 299\ \text{g} \), \( \text{mass of hydrogen} = 33.5\ \text{g} \).
So, \( m_{O_2} = 299 - 33.5 \)

Step3: Calculate the result

\( 299 - 33.5 = 265.5\ \text{g} \)

Answer:

The mass of oxygen that reacted is \( 265.5\ \text{g} \)