The ideal gas law: PV=nRT Show work 2) 2 NaN3(s)-->2 Na(s) + 3 N2 Calculate the

Question

The ideal gas law: PV=nRT

Show work

2) 2 NaN3(s)-->2 Na(s) + 3 N2

Calculate the volume of N2(g) produced at 21 degrees C and 823 mm Hg when 60.0g Nan3(s) decomposes. (molar mass of NaN3=65.02 g/mol)

Mixed practice:

3) a 200. mL sample of a gas at 25 degrees C undergoes a change in volume to 100. mL at constant pressure. What is the new temperature of the gas in Celcius?

4) If 3.20 L of a gas at 25 degrees Celcius and 732 torr undergo a change to 50. C and 2.70L, what is the new pressure of the gas?

Explanation / Answer

(2)

Moles of NaN3 = mass / molar mass = 60.0 / 65.02 = 0.923 mol

From the balanced equation,

2 mol of NaN3 produces 3 mol of N2

then, 0.923 mol of NaN3 produces 3 * 0.923 / 2 = 1.38 mol of N2

n = 1.38 mol

T = 273.15 + 21 = 294.15 K

P = 823 mmHg = 823 / 760 atm = 1.08 atm

R = 0.0821 L.atm.K-1.mol-1

V = ?

Formula, P V = n R T

V = 1.38 * 0.0821 * 294.15 / 1.08

V = 30.8 L

(3)

At constant pressure, V/T = constant

V1 / T1 = V2 / T2

200. / 298.15 =100. / T2

T2 = 149. K

(4)

For, same number of moles of gas, PV/T = constant.

P1 V1 / T1 = P2 V2 / T2

732 * 3.20 / 298.15 = P2 * 2.70 / 323.15

P2 = 940. torr

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