Question

A solution contains 10.0 g pentane, 10.0 g hexane and 10.0 g benzene. What is the mole fraction of hexane?
A. 0.30
C. 0.32
B. 0.31
D. 0.33

Answer 1

Answer:

correct option is B

Explanation:

pentane is C5H12

Its molar mass is 5x12+12x1=72

given wt. of pentane is 10gram

so moles of pentane in soln is 10/72=

similarly hexane is C6H14

molar mass of hexane is 6x12+14x1=86

given wt. of hexane in soln is 10g

moles of hexane in soln. 10/72

for benzene

molar mass is 6x12+6x1=78

given wt. is 10 g

so moles of benzene in soln. is 10/78

total moles in soln. = moles of pentane +moles of hexane +moles of benzene

= 10/72+10/86+10/78

= 0.38 ≈

so mole fraction of hexane is (moles of hexane)/(total moles present in soln )

that is (10/86)/0.38= 0.308

≈ 0.31

Answer 2

Answer:

0.303

Explanation: