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0.465 g sample of an unknown compound occupies 245 mL at 298K and 1.22 atm. What is the molar mass of the unknown compound?

Answer 1

Noah Aldrich

The gas has a molar mass of 38.0 g/mol.

The Ideal Gas Law is one tool for solving this issue.

#PV = nRT#

#n = m/M_"r"#, where #m# is the mass and #M_r# is the relative molar mass. So,

#PV = (m/M_"r")RT#

#M_"r" = (mRT)/(PV) = ("0.465 g" × 0.082 06 cancel("L·atm·K⁻¹")"mol⁻¹" × 298 cancel("K"))/(1.22 cancel("atm") × 0.245 cancel("L")) = "38.0 g/mol"#

38.0 g/mol is the relative molar mass.

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Answer 2

Mateo Aguilar

38.4g

#M_r=38.4#

#PV=nRT#

#P=1.22xx1.0xx10^(5)Pa#

#T=298K#

#V=245xx10^(-6)m^(3)#

#R=8.31"J/K/mol"#

#n=(PV)/(RT)=(1.22xx10^(5)xx245xx10^(-6))/(8.31xx298)#

#n=0.0121#

0.0121 moles therefore weigh 0.465g.

So 1 mole weighs #0.465/0.0121= 38.4"g"#

nb Using 8.31 for R after converting to Pa, it depends on the R value that you are provided.

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Answer 3

Olivia Anton

The molar mass of the unknown compound is 114 g/mol.

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Answer from HIX Tutor

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.