# A gas mixture contains 75.2\% nitrogen and 24.8\% krypton by

A gas mixture contains $75.2\mathrm{%}$ nitrogen and $24.8\mathrm{%}$ krypton by mass. What is the partial pressure of krypton in the mixture if the total pressure is 745 mm Hg?
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hysgubwyri3

Each percentage represents the number of grams of an element per 100.0 grams of that gas mixture. Convert these masses to moles using molar masses.
$=2.6844mol{N}^{2}$

$=0.29595molKr$
Use the mole fraction equation to determine the partial pressure of krypton
${P}_{Kr}={X}_{Kr}{P}_{\to t}$
$=\left(\frac{{n}_{Kr}}{{n}_{Kr}+{n}_{{N}^{2}}}\right){P}_{\to t}$
$=\left(\frac{0.29595mol}{0.29595mol+2.6844mol}\right)\left(745mmHg\right)$
$=74.0mmHg$

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Jeremy Merritt

Step 1
Given data
A gas mixture contains -
Nitrogen $=75.2\mathrm{%}$
krypton $=24.8\mathrm{%}$
total pressure is 745 mmHg.
Step 2
Solution-
calculate the mole fraction of the component-
Mole fraction of tha erypton —

${X}_{2}=\frac{0.296mol}{\left(2.68+0.296\right)mol}=0.0995$
partial pressure of the crypton:
total pressure x mole fraction of the crypton
$745mmHg×0.0995=74.12mmHg$

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karton

Step 1
Given:
Mass of nitrogen =75.2 g (75.2% by mass)
Mass of krypton =24.8 g (24.8% by mass)
Total pressure =745 mm Hg
Step 2
To determine the partial pressure of krypton as follows,
Molar mass of nitrogen =28.02$\frac{g}{mol}$
Calculating the moles of nitrogen using the formula,

$=\frac{75.2g}{28.02\frac{g}{mol}}$
=2.68mol
Molar mass of krypton =83.80$\frac{g}{mol}$
Calculating the moles of krypton using the formula,
Mass of krypton

$=\frac{24.8g}{83.80\frac{g}{mol}}$
=0.296mol
Step 3
To calculate the mole fraction of krypton,
Moles of krypton,
$=\frac{0.296mol}{\left(2.68+0.296\right)mol}=0.0995$
Partial pressure of krypton =Total pressure * Mole fraction of krypton
Substituting the values in the above formula,
Partial pressure of krypton =745mmHg*0.0995=74.1mmHg
Hence, the partial pressure of krypton in the given mixture is 74.1mmHg .