To determine how many moles of oxygen gas (O2) are needed to react with 20 moles of sodium (Na), we can refer to the balanced chemical equation:
4 Na + O2 → 2 Na2O
From the equation, we can see that 4 moles of sodium react with 1 mole of oxygen gas. Therefore, we can set up a ratio based on this information:
If 4 moles of Na require 1 mole of O2, then:
1 mole O2 / 4 moles Na
Now, to find out how many moles of O2 are needed for 20 moles of Na, we can calculate:
moles of O2 = (20 moles Na) * (1 mole O2 / 4 moles Na) = 20 / 4 = 5 moles O2
Thus, you need 5 moles of oxygen gas (O2) to react with 20 moles of sodium (Na).