Question

Determine the grams of oxygen gas that reacts with 1.75 moles of hydrogen gas

Answer 1

The reaction between Hydrogen and Oxygen under normal conditions is characterized by the following balanced equation:
         2 H₂   +   O₂   →   2 H₂O

The mole ratio (based on the coefficient used to balance the chemical equation) of H₂  :  O₂   is  2   :   1.

Thus there are two times as many moles of H₂ in the reaction as there are moles of O₂. 

∴ if the moles of H₂  =  1.75 mol

then the moles of O₂ = 1.75 mol ÷ 2
                                    =  0.875 mol

Now, Mass =  Moles  ×  Molar Mass
Thus the mass of oxygen gas = 0.875 mol  ×  32 g/mol  =  28 g

Thus the answer is 28 grams.