Step 1 - Understanding how mole relates to temperature, pressure and volume
These variables are related according to the ideal gas equation:
![pV=nRT](https://img.qammunity.org/2023/formulas/chemistry/college/orryx72yevv9wszhddbe05jkujkcmsdrrl.png)
We can use this equation to predict the behavior as well as the quantity of a gas, given that the remaining variables are given.
Step 2 - Using the equation to solve the equation
According to the exercise:
![\begin{gathered} p=2.5atm \\ T=25°C\text{ \lparen298 K\rparen} \\ V=1.67L \\ n=? \end{gathered}](https://img.qammunity.org/2023/formulas/chemistry/college/l1qpykaukdhs5ohn7mmd8g3xewbm4ax3ny.png)
Setting the values in the equation:
![2.5*1.67=nR*298](https://img.qammunity.org/2023/formulas/chemistry/college/d5hgv2m4j6vh8t9dq5qrtsd5jhqfu4ytel.png)
We need to make two observations now: the temperature must be in Kelvin in this equation for it to work. R stands for the universal gas constant, as has the value of 0.082 atm.L/mol.K.
Therefore:
![\begin{gathered} 2.5*1.67=n*0.082*300 \\ \\ n=(4.17)/(24.6)=0.169\approx0.17 \end{gathered}](https://img.qammunity.org/2023/formulas/chemistry/college/totdy5ecr0evhjisbeuuvwg7svr31r4dil.png)
Answer: the amount of moles used is 0.17 moles.