Benzene weighing 390 g, you need to find the mass of cyclohexane.

First of all, let’s write the reaction for obtaining cyclohexane from benzene:

C6H6 + 3H2 = C6H12;

We are given the mass of benzene, which means that we can find the amount of its mol (n) that have entered into the reaction:

n (C6H6) = m (C6H6): M (C6H6) = 390 g: 78 g / mol = 5 mol.

Further, we look at the equation and see that before C6H6 and C6H12 there is conventionally a coefficient of 1, which tells us that n (C6H6) = n (C6H12) = 5 mol.

Now it remains to find only the mass of C6H12:

m (C6H12) = n (C6H12) * M (C6H12) = 5 mol * 84 g / mol = 420 g of cyclohexane is formed during the reaction.