Question

If 1.0 mol of N2 and 3.0 mol of H2 in a closed container initially at STP react completely in the reaction shown below, then the final pressure in the flask will be ________ atm at 273 K.

Answer 1

Answer:

$p_f=0.5atm$

Explanation:

Hello!

In this case, since the reaction between nitrogen and hydrogen produces ammonia:

$N_2+3H_2\rightarrow 2NH_3$

We can compute the volume of the container by using the ideal gas law at STP (1 atm and 273.15 K):

$V=\frac{4.0mol*0.08206\frac{atm*L}{mol*K}*273.15K}{1atm}=89.7L$

Next, since nitrogen and hydrogen are in a 1:3 mole ratio, we understand all the nitrogen and hydrogen are consumed and only ammonia remains at the end of the reaction in the following amount:

$n_{NH_3}=1.0molN_2*\frac{2molNH_3}{1molN_2} =2.0molNH_3$

Thus, the final pressure turns out:

$p_f=\frac{2.0mol*0.08206\frac{atm*L}{mol*K}*273.15K}{89.7L}\\\\p_f=0.5atm$

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