Question

34 atoms of carbon react with 22 molecules of hydrogen gas. How many molecules of methane will be formed & what will be left over?

Answer 1

Answer: 11 molecules of methane and carbon will be left over.

Explanation: $C+2H_2\rightarrow CH_4$

According to given balanced equation,

1 atom of carbon reacts with 2 molecules of hydrogen to form 1 molecule of methane.

Thus 32 atoms of carbon will react with=$\frac{2}{1}\times 32=64$ molecules of hydrogen.

But only 22 molecules of hydrogen are available.

Thus we see it the other way.

2 molecules of hydrogen  react with 1 atom of carbon

22 molecules of hydrogen  will react with=$\frac{1}{2}\times 22=11$

atoms of carbon

Thus hydrogen is the limiting reagent as it limits the formation of product. Carbon is excess reagent and (34-11)=23 atoms of carbon will be left over.

2 molecules of hydrogen form 1 molecule of methane.

22 molecules of hydrogen form=$\frac{1}{2}\times 22= 11$ molecules of methane.

Answer 2

Each carbon atom will react with 4 hydrogen atoms to form methane ($C H_{4}$) Since there are 2 hydrogen atoms in a hydrogen molecule ($H_{2}$) then each carbon atom will react with 2 hydrogen molecules. Since there are 22 hydrogen molecules half as many methane molecules will be formed, so 11. Then we can subtract 11 from 34 to find the number of carbon atoms left over.

So in summary, 11 methane molecules will be formed and there will be 23 carbon atoms left over.