Question

A 250 mL sample of nitrogen(N2) has a pressure of 745 mm Hg at 30 C.What is the mass of nitrogen? @Physics

Answer 1

Well first thing you have to do is convert some of the data to proper units. 250 mL = 0.250 L. 745 mmHg X (1atm/760 mmHg) = approximately 0.98 atm. 30 C = 303 K.

Now use PV = nRT, and arrange to calculate for n. PV/RT = n
(0.98 atm)(0.250 L)/(0.0821L*atm/(mol*K)(303)
= approximately 0.01moles of nitrogen gas.

Multiply the moles by the molar mass of nitrogen gas, 28.00 g/mol to get the mass of nitrogen in gram (0.276 g).