Question

How many moles of H2 are in a flask with a volume of 2500 mL at a pressure of 30.0 kPa and a temperature of 27oC?

Answer 1

Answer:

0.0300 moles of H₂

Explanation:

The original equation is PV = nRT. We need to change this to show moles (n).

n = $\frac{PV}{RT}$

It's important to convert your values to match the constant (r) in terms of units.

30.0 kPa = 0.296 atm

2500 mL = 2.50 L

27 °C = 300 K

Now, plug those values in to solve:

n = $\frac{(0.296)(2.50)}{(0.0821)(300)}$    -  for the sake of keeping the problem clean, I didn't include the units but you should just to make sure everything cancels out :)

Finally, you are left with n = 0.0300 moles of H₂