Combined gas law problems

Question

A car tire has 65 moles of nitrogen gas (N2) and a volume of 87 liters. If the container has 776 more grams of N2 added, what will be the new volume of the tire? Hint: you need to determine convert grams into moles, and then add that to the original number of moles to get your 2nd number of moles.

Answer 1

Let's convert the 776 g of N₂ to moles.

776 g N₂ / 28 g N₂ = 27.7 moles

Use Avogadro's Law which is V₁ / n₁ = V₂ / n₂

So 87 L / 65 mol = V₂ / 28 mol

Solve for unknown V₂ with algebra

(87)(28) / (65) = 37 L