Question

A tank contains 1500 L of argon gas. The pressure is 11690 kPa and the temperature is 35ºC. How many moles of

argon are in the tank?


Show your work

Answer 1

Answer: 6,847.7 moles of Argon Gas

Step-by-step explanation:

For this question, you need to use the Ideal Gas Equation (PV = nRT).

• P is pressure (commonly in kPa or atm)
• V is volume occupied by the gas (in L)
• n is the number of moles, aka what we're trying to find here.
• R is the Ideal gas constant (8.314 (kPa*L)/(mol*K), or 0.0821 (atm*L)/(mol*K)
• T is the temperature (in Kelvins (K). In order to convert from Celsius to Kelvin, just add 273.)

We can rearrange this equation to calculate the number of moles:

n = PV/RT

Then, we can plug in the values (Caution: we have to use 8.314 for our Ideal gas constant since P is in kPa for this question)

...and we have our answer! 6,847.7 moles of Argon Gas.

Also, make sure to adjust to significant figures!

Answer 2

6843.99 mol (2 d.p.)

Step-by-step explanation:

To calculate the number of moles of argon in the tank, we can use the Ideal Gas Law.

Ideal Gas Law

`\boxed{PV=nRT}`

where:

• P is the pressure measured in kilopascals (kPa).
• V is the volume measured in liters (L).
• n is the number of moles.
• R is the ideal gas constant (8.31446261815324 kPa L mol⁻¹ K⁻¹).
• T is the temperature measured in kelvin (K).

First convert the given temperature from Celsius to kelvin by adding 273.15:

`\implies \sf T=35+273.15=308.15\;K`

Therefore, the values to substitute into the equation are:

• P = 11690 kPa
• V = 1500 L
• R = 8.31446261815324 kPa L mol⁻¹ K⁻¹
• T = 308.15 K

Rearrange the formula to isolate n:

`\implies n=(PV)/(RT)`

Substitute the values into the formula and solve for n:

`\implies n=(11690 \cdot 1500)/(8.3144626... \cdot 308.15)`

`\implies n=(17535000)/(2562.10165...)`

`\implies n=6843.99073...`

`\implies n=6843.99\; \sf mol\;(2\;d.p.)`

Therefore, there are 6843.99 moles of argon in the tank (to two decimal places).