An imaginary ideal gas has a density of 3 g/L at STP. What is the molar mas of this gas?
You know that you're dealing with a sample of an unknown gas that has a density of
In order to find the gas' molar mass, you need to know two things
- the mass of this sample of gas
- the number of moles of gas present in this sample
Now, STP conditions imply a pressure of
#"100 kPa"# and a temperature of#0^@"C"# .You will have to use the ideal as law
#color(blue)(PV = nRT)# in order to try to find a relationship between the gas' density and its molar mass.
You know that molar mass is defined as mass per mole, so you can say that
#M_"m" = m/n implies n = m/M_"m"# Replace the number of moles in the ideal gas law equation to get
#PV = m/M_"m" * RT# You also know that density is defined as mass per unit of volume
#rho = m/V# Notice what happens if you divide both sides of the ideal gas law equation by
#V#
#(P * color(red)(cancel(color(black)(V))))/color(red)(cancel(color(black)(V))) = m/M_"m" * (RT)/V#
#P = underbrace(m/V)_(color(green)("density")) * (RT)/M_"m" = rho * (RT)/M_"m"# Finally, isolate the molar mass on one side of the equation to get
#M_"m" = rho * (RT)/P# Now all you have to do is plug in your values - remember that
#R = 0.082("atm" * "L")/("mol" * "K")# and that the pressure must be expressed in atm and the temperature in Kelvin!
#M_"m" = 3"g"/color(red)(cancel(color(black)("L"))) * (0.082(color(red)(cancel(color(black)("atm"))) * color(red)(cancel(color(black)("L"))))/("mol" * color(red)(cancel(color(black)("K")))) * (273.15 + 0)color(red)(cancel(color(black)("K"))))/(100/101.325color(red)(cancel(color(black)("atm"))))#
#M_"m" = "68.085 g/mol"# SInce you only gave one sig fig for the density of the gas, the answer will be
#M_"m" = color(green)("70 g/mol")#
By signing up, you agree to our Terms of Service and Privacy Policy
The molar mass of the gas is approximately 44.8 g/mol.
By signing up, you agree to our Terms of Service and Privacy Policy
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
- What is the density of neon gas given a pressure of #505*mm*Hg#, and a temperature of #318*K#?
- How many molecules are in 4.5 L of #CO_2# at STP?
- What are some common mistakes students make with the molar volume of a gas?
- After 0.600 L of #Ar# at 1.40 atm and 210 #"^o#C is mixed with 0.200L of #O_2# at 398 torr and 120 #"^o#C in a 400 -mL flask at 29 #"^o#C, what is the pressure in the flask?
- What is the relationship between the combined gas law and the ideal gas law?

- 98% accuracy study help
- Covers math, physics, chemistry, biology, and more
- Step-by-step, in-depth guides
- Readily available 24/7