Question

A solution contains 180 g of glucose (C6H12O6) and 162 g of water. What is the mole fraction of glucose?

The choices are:
a. 1.0
b. 10.0
c. 0.0010
d. 0.10
e. 0.010

Answer 1

d. 0.10

Step-by-step explanation:

So, according to definition of mole fraction:

`Mole\ fraction\ of\ glucose=\frac {n_(glucose)}{n_(glucose)+n_(water)}`

Given,

Mass of glucose = 180 g

Molar mass of glucose = 180 g/mol

The formula for the calculation of moles is shown below:

`moles = (Mass\ taken)/(Molar\ mass)`

Thus,

`Moles= (180\ g)/(180\ g/mol)`

`Moles_(glucose)= 1\ mol`

Given,

Mass of water = 162 g

Molar mass of water = 18 g/mol

The formula for the calculation of moles is shown below:

`moles = (Mass\ taken)/(Molar\ mass)`

Thus,

`Moles= (162\ g)/(18\ g/mol)`

`Moles_(water)= 9\ mol`

Applying in the expression for mole fraction as:-

`Mole\ fraction\ of\ glucose=\frac {n_(glucose)}{n_(glucose)+n_(water)}`

`Mole\ fraction\ of\ glucose=\frac {1}{1+9}=0.10`

Correct answer is:- d. 0.10

Answer 2

Answer: d. 0.10

Step-by-step explanation: Mole fraction of a substance is the ratio of the moles of that substance to the total number of moles present.

`{\text {mole fraction of glucose}}=\frac{\text{moles of glucose}}{\text {moles of glucose + moles of water}}`

`Moles=\frac{\text{Given mass}}{\text{Molar mass}}`

Thus
`{\text{moles of glucose}}=(180g)/(180g/mol)=1mol`

`{\text{moles of water}}=(162g)/(18g/mol)=9mol`

`{\text {mole fraction of glucose}=(1)/(1+9)=(1)/(10)=0.10`