Question

5.00 moles of a gas sample has a pressure of 600 torr at 400 K. What is the pressure (in torr) if the amount of gas is changed to 9.00 moles and temperature to 600 K (volume of gas is constant?).

a) 540 b) 1,620 c) 1,260 d) 420

Answer 1

Using Ideal gas equation;

PV = nRT

V = nRT/P

Here

P = pressure = 600 torr

V = Volume = ?

n = moles = 5 mole

R = gas constant = 62.364 L torr mol^-1 K^-1

T = Temperature = 400 K

Substituting the values, we get;

V = (5 mol) (62.364 L torr mol^-1 K^-1) (400 K) / (600 torr)

= 207.88 L

Now,

Volume is constant , so,

V = 207.88 L

n = 9 mol

T = 600 K

R = 62.364 L torr mol^-1 K^-1

P =?

Substituing the values, in the equation PV= nRT, we get

P x (207.88 L) = (9 mol) (62.364 L torr mol^-1 K^-1) (600 K)

P = (9 mol) (62.364 L torr mol^-1 K^-1) (600 K) / (207.88 L)

= 1620 torr

So, answer is option (b)