Chemistry Gas Question

Question

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A solution of H2 (1.00 g) and He (5.00 g) occupies a volume of 5.00 dm3 at 20 ° C. Indicate the

total moles of the two gases and the pressure exerted by the solution of the two gases:

A. 1.75 mol; 4.20 atm

B. 1.75 mol; 8:40

C. 8.50 mol; 16.8 atm

D. 3.45 mol; 6:30

E. 12.5 mol; 5.66 atm

Answer 1

First we find total number of moles of gas:

1.00 g H₂ x 1 mol H₂ / 2 g = 0.5 mols H₂

5.00 g He x 1 mol He / 4 g = 1.25 mols He

Total moles = 1.75 mols

Next, we use the ideal gas law to find the total of the two gases:

PV = nRT

P = pressure = ?

V = volume = 5.00 dm³ = 5 L

n = moles = 1.75 mols

R = gas constant = 0.0821 Latm/Kmol

T = temperature in Kelving = 20C + 273 = 293K

Solving for P we have ... P = nRT/V

P = (1.75)(0.0821)(293) / 5

P = 8.40 atm

So ANSWER is B. 1.75 mol; 8:40