Question

A 1.2 L flask contains 0.500 mole of ammonia (NH3) at 150°C. Calculate the pressure of the ammonia inside the flask.

Answer 1

This sounds like an Ideal Gas Law problem, because you're given volume (1.2 L), n (0.500 mol), and temperature (150+273=423K). R is always the constant 0.00821L x atm/mol x K
Okay, so first rearrange the gas law so that P is isolated: P = nRT/V
Now, you just plug in all of the values: P = 0.500mol x 423K x 0.0082L x atm/K x mol x 1.2L

When you cross out all of the matching units on the top and bottom of the equation, you'll be left with atm.
The answer should be: 1.4atm (rounded to 2 significant figures)