1) Write the chemical equation
[tex]N_2+3H_2\rightarrow2NH_3[/tex]
2) Convert grams of H2 into moles of H2.
[tex]\text{mol H}_2=7gH_2\cdot\frac{1molH_2}{2.016gH_2}=3.472molH_2[/tex]
3) Moles of N2 needed to react with H2
[tex]\text{mol N}_2=3.472molH_2\cdot\frac{1molN_2}{3molH_2}=1.157molN_2[/tex]
4) Plug values in the frame
1.157 mol N2 is needed in the reaction.
