Question

34.05 mL of phosphorus vapours weighs 0.0625 g at 546°C and 0·1 bar pressure. what is the molar mass of phosphorus?

Solution

Here P = 0.1 bar;
$straight V space equals space 34.05 space mL space equals space fraction numerator 34.05 over denominator 1000 end fraction dm cubed space equals space 34.05 space cross times space 10 to the power of negative 3 end exponent dm cubed space straight R space equals space 0.083 space bar space dm cubed straight K to the power of negative 1 end exponent mol to the power of negative 1 end exponent comma straight T space equals space 273 space plus 546 space equals space 819 space straight K$
Applying general gas equation,
$PV space equals space nRT space space or space space space straight n space equals space PV over RT comma substituting space the space values comma space we space have$
$straight n space equals space fraction numerator 0.1 space bar space cross times space left parenthesis 34.05 space cross times space 10 to the power of negative 3 end exponent dm cubed right parenthesis over denominator 0.083 space bar space dm cubed space straight K to the power of negative 1 end exponent space mol to the power of negative 1 end exponent space cross times space 819 straight K end fraction space equals space 5 space cross times space 10 to the power of negative 4 end exponent space mol therefore space space space Mass space of space 1 space mole space equals space fraction numerator 0.0625 over denominator 5 space cross times space 10 to the power of negative 4 end exponent end fraction straight g space equals space 125 space straight g therefore space space Molar space mass space equals space 125 space straight g space mol to the power of negative 1 end exponent$

Some More Questions From States of Matter Chapter

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States Of Matter

34.05 mL of phosphorus vapours weighs 0.0625 g at 546°C and 0·1 bar pressure. what is the molar mass of phosphorus?

Some More Questions From States of Matter Chapter

Which state of matter has a definite volume but no definite shape?

What is absolute temperature?

What is the absolute zero temperature?

Can absolute zero temperature be attained for a gas?

How pressure of a given sample of gas is related to absolute temperature at constant volume?

How is the pressure of a gas related to the number of molecules of the gas at constant temperature and volume?

What is standard (or normal) temperature and pressure (STP)?

What does SATP stand for? Define it.

What is the value of molar volume at STP?

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