A sugar solution consists of 0.25
| mol of glucose dissolved in 2.0 L of
water. What is the molarity of the
solution?

Explanation:

Your goal when trying to find a solution's molarity is to determine how many moles of solute you have in one liter of solution.

Notice that your solution has a volume of 100.0 mL. Since

∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa1 L=103mLaa∣∣−−−−−−−−−−−−−−−−

you can say that your solution has a volume that is equivalent to 110th of 1 L. Therefore, the number of moles that will be present in your sample will represent 110th of the number of moles present in 1 L of this solution.

So, use sucrose's molar mass to find the number of moles present in your sample

10.0g⋅1 mole sucrose342.34g=0.02921 moles sucrose

So, if this is how many moles you have in 100.0 mL of this solution, it follows that 1 L will contain

1L solution⋅103mL solution1L solution⋅0.02921 moles100mL solution=0.2921 moles

You get 0.2921 moles of sucrose, you solute, per liter of solution, which means that the solution's molarity will be

molarity=c=∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa0.292 mol L−1aa∣∣−−−−−−−−−−−−−−−−−

The answer is rounded to three sig figs.

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