chemistry hw Calculate the density of a NH3 gas having a pressure of 34mmHg and a temperature of 233K.

Question

Calculate the density of a NH3 gas having a pressure of 34mmHg and a temperature of 233K.

Answer 1

Ideal gas law:

PV = nRT

Because they ask for density, and density is mass/volume, we need to find the mass of NH₃ present.

Given:

P (pressure) = 34 mm Hg (to convert to atm, divide to 760 since 1 atm = 760 mm Hg)

V (volume) = not given to you, but assume it is 1 liter (in density problems, this is one way to do it)

R (gas constant) = 0.0821 Latm/Kmol (note units have atm, that's why we converted mm Hg to atm)

T (temperature in K) = 233K

Needed:

n (moles) = ?

Solve for n (moles of NH₃):

n = PV/RT plug in the above values and solve for n

Now that you have n (moles), you convert that to grams of NH₃ by multiplying by the molar mass of NH₃ (17 g/mol)

Now that you have grams of NH₃ and you know the volume is 1 liter, you can get the density because density is defined as mass / volume. Density of NH₃ = grams NH₃ / 1 liter (answer)