1. Carbon Dioxide gas has a mass of 86.3 grams. If the molar mass of the sample is 44.2 grams, how many moles of CO2 are present in the sample?
2. That sample of gas is in a 23.2 L container at 12 degrees Celcius. Calculate for the pressure.
1. mols = grams/molar mass = ?
2. Use PV = nRT
You know V, n, R, T. Remember to convert T to kelvin.
Post your work if you get stuck.
V = 23.2 L
T = 285 K
n = ?
R = ?
How do you find the other variables for both questions?
You calculated mols in # 1. mols = n in the formula PV = nRT
R = a constant of 0.08206 if you want P in atmospheres. If you want R in kPa use 8.314
From #1, surely you know how to calculate molar mass of a compound. For CO2 it is C = 12; O = 16 x 2 = 32 and 12 + 32 = 44.
Thank you. I am still stuck on how to answer #1. The molar mass is 44.2 grams. Since CO2 is 86.3 grams, does that mean that there are two Carbon dioxides present? I'm assuming I double the molar mass here.
mols = grams/molar mass = ?
mols = 86.3/44.2 = 1.95 mols CO2; however, I don't remember CO2 being 44.2. I don't think CO2 has a molar mass of 44.2
C is 12.01 and O is 32 so I use molar mass CO2 as 44 but I suppose we could plug in 44.01. Then 86.3/44.01 = 1.96 mols CO2
Hope that clears this up.
To find the number of moles of CO2 present in the sample, you can use the formula:
moles = mass / molar mass
In this case, the mass of the sample is given as 86.3 grams, and the molar mass of CO2 is 44.2 grams. Plugging these values into the formula:
moles = 86.3 g / 44.2 g/mol ≈ 1.95 mol
Therefore, there are approximately 1.95 moles of CO2 present in the sample.
For the second question, to calculate the pressure of the gas in the container, you can use the ideal gas law equation:
PV = nRT
where:
- P is the pressure of the gas
- V is the volume of the container
- n is the number of moles of gas
- R is the ideal gas constant (0.0821 L⋅atm/mol⋅K)
- T is the temperature in Kelvin
To convert from Celsius to Kelvin, you add 273.15:
Temperature in Kelvin = 12°C + 273.15 = 285.15 K
Plugging the values into the ideal gas law equation:
P * 23.2 L = 1.95 mol * 0.0821 L⋅atm/mol⋅K * 285.15 K
P * 23.2 L = 46.25 L⋅atm
P = 46.25 L⋅atm / 23.2 L ≈ 1.99 atm
Therefore, the pressure of the gas in the container is approximately 1.99 atm.