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

##### 1 Answer

#### Explanation:

In order to find the **mole fraction** of glucose in this solution, you need to know

thenumber of molesof glucosethetotal number of molespresent in the solution

To find the number of moles of glucose present in **molar mass**, which is equal to

Your sample of glucose will thus contain

#180 color(red)(cancel(color(black)("g"))) * overbrace("1 mole glucose"/(180.16color(red)(cancel(color(black)("g")))))^(color(blue)("molar mass of glucose")) = "0.9991 moles glucose"#

Now do the same for water, using the fact that its **molar mass** is equal to

#162 color(red)(cancel(color(black)("g"))) * overbrace("1 mole water"/(18.015color(red)(cancel(color(black)("g")))))^(color(purple)("molar mass of water")) = "8.9925 moles water"#

The **total number of moles** present in this solution will be

#n_"total" = "0.9991 moles" + "8.9925 moles" = "9.9916 moles"#

Now, the mole fraction of glucose is equal to the number of moles of glucose divided by the *total number of moles* present in solution.

In your case, this is equal to

#chi_"glucose" = (0.9991 color(red)(cancel(color(black)("moles"))))/(9.9916color(red)(cancel(color(black)("moles")))) = 0.10#

The answer is rounded to two **sig figs**, the number of sig figs you have for the mass of glucose.