Question

11. A 26.8 L sample of nitrogen at 4.85 atm and 25 deg celusis is simultaneously expanded to 63.8 L and heated to 38 degress celusis. What is the new pressure of the gas.

A. 232 ATM

B. 195 ATM

C. 2.13 ATM

D. 338 ATM

E. 3.10 ATM

12. A 6.08 L cylinder contains 6.59 g of methane, CH4, at a pressure of 3440 mmHg. What is the tempature of the gas?

A. 1090 deg celusis

B. -150 deg celusis

C. 543 deg celusis

D. 5380 deg celusis

E. 816 deg celusis

Answer 1

11)

Given:

Pi = 4.85 atm

Vi = 26.8 L

Vf = 63.8 L

Ti = 25.0 oC

= (25.0+273) K

= 298 K

Tf = 38.0 oC

= (38.0+273) K

= 311 K

use:

(Pi*Vi)/(Ti) = (Pf*Vf)/(Tf)

(4.85 atm*26.8 L)/(298.0 K) = (Pf*63.8 L)/(311.0 K)

Pf = 2.13 atm

Answer: 2.13 atm

12)

Molar mass of CH4,

MM = 1*MM(C) + 4*MM(H)

= 1*12.01 + 4*1.008

= 16.042 g/mol

mass(CH4)= 6.59 g

use:

number of mol of CH4,

n = mass of CH4/molar mass of CH4

=(6.59 g)/(16.04 g/mol)

= 0.4108 mol

Given:

P = 3440.0 mm Hg

= (3440.0/760) atm

= 4.5263 atm

V = 6.08 L

n = 0.4108 mol

use:

P * V = n*R*T

4.5263 atm * 6.08 L = 0.4108 mol* 0.08206 atm.L/mol.K * T

T = 816 K

= (816-273) oC

= 543 oC

Answer: 543 oC