Question

a mixture of helium and nitrogen has a total pressure of 2.8 atm. the partial pressure of helium is 1.0 atm. how many moles of nitrogen are present in 0.75 l at 425 k? 0.039 mols 0.021 mols 0.060 mols 0.082 mols

Explanation:

Step1: Calculate the partial pressure of nitrogen

According to Dalton's law of partial pressures, \(P_{total}=P_{He}+P_{N_2}\). So \(P_{N_2}=P_{total}-P_{He}\).
\(P_{N_2}=2.8 - 1.0=1.8\space atm\)

Step2: Use the ideal gas law \(PV = nRT\) to find the number of moles of nitrogen

The ideal gas law is \(n=\frac{PV}{RT}\), where \(R = 0.0821\space L\cdot atm/(mol\cdot K)\), \(P = 1.8\space atm\), \(V=0.75\space L\), \(T = 425\space K\)
\(n=\frac{1.8\times0.75}{0.0821\times425}\)
First, calculate the numerator: \(1.8\times0.75 = 1.35\)
Then, calculate the denominator: \(0.0821\times425=34.8925\)
\(n=\frac{1.35}{34.8925}\approx0.039\space mol\)

Answer:

0.039 mols