Given 2H2 + O2 --> 2H2O. How many moles of oxygen are required to react completely with 1.2 grams of hydrogen to form water?

Answer 1

To determine how many moles of oxygen are required to react completely with 1.2 grams of hydrogen, we can follow these steps:

1. Calculate the number of moles of hydrogen (H₂): The molar mass of hydrogen (H₂) is approximately 2.02 g/mol (since each H atom is about 1.01 g/mol, and there are 2 H atoms in H₂).

   $$\text{Moles of }{H}_2=\frac{\text{mass of }{H}_2}{\text{molar mass of }{H}_2}=\frac{1.2\text{ g}}{2.02\text{ g/mol}}\approx 0.594\text{ moles}$$

2. Use the balanced chemical equation: The balanced reaction is: $$2H_2+O_2\to 2H_{2}O$$ From the equation, we see that 2 moles of hydrogen react with 1 mole of oxygen.

3. Determine moles of oxygen needed: Since 2 moles of hydrogen require 1 mole of oxygen, the ratio of hydrogen to oxygen is 2:1. Therefore, to find the moles of oxygen required for the moles of hydrogen calculated, we can use this ratio:

   $$\text{Moles of }{O}_2=\frac{0.594,\text{moles of }{H}_2}{2}\approx 0.297\text{ moles of }{O}_2$$

Thus, approximately 0.297 moles of oxygen are required to react completely with 1.2 grams of hydrogen to form water.