A gas occupies a volume of 140 mL at 35.0 C and 97 kPa. What is the volume of the gas at STP?

N = ( P )( V ) / ( R ) ( T )

N = ( 97.00 ) ( 140 /1000 ) / ( 8.314 ) ( 308.15 ) = 0.005300 gmol

V sub STP = ( N ) ( R ) ( T sub STP ) / ( P sub STP )

V sub STP = (0.005300 )( 8.314 ) ( 273.15 ) / ( 101.325 ) = 0.118 L. = 118.8 mL

Is my work correct???

The procedure is right and it appears you have substituted correctly but I didn't go through the math.

It's a little easier if you use
(P1V1/T1) = (P2V2/T2) and you get the answer in one math operation instead of two.

Yes, your work is correct. According to the ideal gas law, the number of moles of a gas can be calculated using the equation N = (P)(V) / (R)(T), where P is the pressure, V is the volume, R is the ideal gas constant, and T is the temperature in Kelvin.

In your calculation, you correctly used the given values of pressure (97.00 kPa), volume (140 mL or 140/1000 L), and temperature (35.0°C or 308.15 K) to find the number of moles of the gas, which is approximately 0.005300 gmol.

To find the volume of the gas at standard temperature and pressure (STP), you used the equation V sub STP = (N)(R)(T sub STP) / (P sub STP), where N is the number of moles, R is the ideal gas constant, T sub STP is the standard temperature (273.15 K), and P sub STP is the standard pressure (101.325 kPa or 1 atm).

By plugging in the calculated value of moles (0.005300 gmol), the ideal gas constant (8.314 L⋅kPa/(gmol⋅K)), and the standard temperature and pressure values, you correctly found the volume of the gas at STP, which is approximately 0.118 L or 118.8 mL.

Great job!

Your work is mostly correct, but there is a slight error in your calculations. Let's go through the steps again to find the correct answer.

Step 1: Calculate the number of moles (N) using the given values of pressure (P), volume (V), temperature (T), and the ideal gas law equation:

N = (P * V) / (R * T)

N = (97.00 kPa) * (140 mL / 1000 mL) / (8.314 J/(mol*K)) * (35.0 + 273.15) K
= (97.00 * 0.140) / (8.314 * 308.15)
≈ 0.00529653 mol

Step 2: Calculate the volume of the gas at STP using the number of moles (N), the ideal gas law equation, and the values of temperature (T) and pressure (P) at STP:

V_STP = (N * R * T_STP) / P_STP

Remember, at STP temperature (T_STP) is 273.15 K and pressure (P_STP) is 101.325 kPa.

V_STP = (0.00529653 mol) * (8.314 J/(mol*K)) * (273.15 K) / (101.325 kPa)
= (0.00529653 * 8.314 * 273.15) / 101.325
≈ 0.11815 L
≈ 118.15 mL

So, the correct volume of the gas at STP is approximately 118.15 mL.