Question

Nickel metal will react with CO gas to form a compound called nickel tetracarbonyl (Ni(CO)4), which is a gas at temperatures above ~45°C.A 1.50-L glass bulb is filled with CO gas to a pressure of 1.20 atm at 73.0°C, and then 0.5869 g of pure Ni is added. If the reaction described above occurs and goes to completion at constant temperature, what will the final total pressure in the bulb be? (You can assume that any volume occupied by the solid nickel is negligible compared to the volume of the flask.)

Answer 1

Answer:

The final total pressure in the bulb will be 0.567 atm.

Explanation:

The equation of the reaction is:

Ni + 4CO → Ni(CO)₄

The pressure in the bulb will be the sum of the pressures of each gas (remaining CO and Ni(CO)₄ produced).

The pressure of each gas can be calculated using this equation:

For the gas Ni(CO)₄:

P(Ni(CO)₄) = n * R * T / V

where:

P(Ni(CO)₄) = pressure of Ni(CO)₄

n = number of moles of Ni(CO)₄.

R = gas constant = 0.082 l amt / K mol

T = temperature

V = volume

So we have to find how many moles of Ni(CO)₄ were produced and how many moles of CO remained unreacted.

We can calculate the initial number of moles of CO with the data provided in the problem:

P(CO) = n * R * T / V

solving for n:

P(CO) * V / R * T = n

Replacing with the data:

1.20 atm * 1.50 l / 0.082 (l atm / K mol) * 346K = n

n = 0.06mol.

Now we know how many moles of CO were initially present.

To know how many moles of Ni(CO)₄ were produced, we have to find how many Ni reacted with CO.

Initially, we have 0.5869 g of Ni, which is (0.5869 g * 1 mol/58.69 g) 0.01 mol Ni.

From the chemical equation, we know that 1 mol Ni reacts with 4 mol CO, therefore, 0.01 mol Ni will react with 0.04 mol CO producing 0.01 mol Ni(CO)₄ (see the chemical equation above).

At the end of the reaction, we will have 0.01 mol Ni(CO)₄ and (0.06 mol - 0.04 mol) 0.02 mol CO.

Now we can calculate the pressure of each gas after the reaction:

PNi(CO)₄ = n * R * T / V

PNi(CO)₄ = 0.01 mol * 0.082 (l amt / K mol) * 346K / 1.50 l = 0.189 atm

In the same way for CO:

P(CO) = 0.02 mol * 0.082 (l amt / K mol) * 346K / 1.50 l = 0.189 atm = 0.378 atm

The total pressure (Pt) in the bulb, according to Dalton´s law of partial pressures, is the sum of the pressures of each gas in the mixture:

Pt = PNi(CO)₄ + P(CO) = 0.189 atm + 0.378 atm = 0.567 atm.