Avogadro's law

Tutorial 2

        

A cylinder with a moving piston contains $ 1.40\; g$ of nitrogen at room temperature. More nitrogen was added to the cylinder and the volume was adjusted so that the gas pressure remained the same. How many grams of nitrogen ($ N_2 $) have been added to the cylinder if the volume has been changed from $ 1.00\; L $ to $ 2.50\; L $? (The temperature was kept constant.) Solution (Click): Number of moles of nitrogen at the beginning:..........$n=\frac{m}{M}$ = $\frac{1.40}{28.0}= 0.050\; mol$ As ..........temperature and pressure remain constant, Avogadro's law is applicable: Avogadro's law: ..........$\frac{V_1 }{n_1}=\frac{V_2 }{n_2}$ Calculation of the final number of moles: ..........$n_1=\frac{n_2\cdot V_1}{V_2}$ = $\frac{0.05 \cdot 2.50}{1,00} = 0.125\;mol$ Added number of moles ..........$0.0125-0.050= 0.075 \; mol$ Added mass: ..........$m=n\cdot M=0,075\cdot 28.0= 21.0\;g$