Question

If I have an unknown quantity of gas at a pressure of 9.3 atm, a volume of 19.8 liters, and atemperature of 68 °C, how many moles of gas do I have?

Answer 1

We must find the moles => n

First, we assume ideal gas conditions, so we can use the ideal gas law:

`p\text{ x V = n x R x T (1)}`

p = pressure in atm

V = volume in L

n = moles = needs to be found

T = temperature in K, to get Kelvin we must do this procedure:

T (°C) + 273 = T (K)

68 °C + 273 = 341 K

R = gas constant = 0.082 atm x L / mol x K, we take this value of R because of the units we already have.

Procedure:

Clear "n" from (1)

`\begin{gathered} \frac{p\text{ x V}}{R\text{ x T}}=\text{ n} \\ \frac{9.3\text{ atm x 19.8 L}}{0.082\text{ }\frac{atm\text{ L}}{\text{mol K}}\text{ x 341 K}}=\text{ 6.6 moles (approx.) = n} \end{gathered}`

Answer: n = 6.6 moles