How many moles of hydrogen do you need to take to get 18 moles of heptane from heptin?

Let’s implement the solution:

In accordance with the condition, we write down the equations of the processes:
С7Н12 + Н2 = С7Н14 – hydrogenation, heptene obtained;

С7Н14 + Н2 = С7Н16 – addition of hydrogen, heptane was formed.

Let’s write in total:
Y -? Y = 18 mol;

C7H12 + 2H2 = C7H16

Proportion:
X mol (H2) – 18 mol (C7H16);

-2 mol          – 1 mol from here, X mol (H2) = 2 * 18/1 = 36 mol.

Answer: You need 36 moles of hydrogen.