Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

Calculation:
– Given:
– Ratio of hydrogen to oxygen by mass for water formation = 1 : 8
– Mass of hydrogen gas given = 3 grams

Using the Mass Ratio for Oxygen:
1. For 1 gram of Hydrogen:
According to the ratio, 1 gram of hydrogen requires 8 grams of oxygen to form water.

2. For 3 grams of Hydrogen:
To find the amount of oxygen needed for 3 grams of hydrogen, we use the ratio.

Mass of oxygen = Mass ratio of hydrogen to oxygen × Mass of hydrogen
Mass of oxygen = 8 × 3 grams = 24 grams

Conclusion:
Hence, to completely react with 3 grams of hydrogen gas, 24 grams of oxygen gas is required based on the 1:8 mass ratio for the formation of water. This demonstrates the proportional relationship between the masses of hydrogen and oxygen in the chemical reaction to produce water.