# Question 2e157

Dec 13, 2015

Dissolve 2.25 grams of glucose in 250 milliliters solvent.

#### Explanation:

To get the weight of glucose to be dissolved in solvent (usually water), first you must do the following computations:

(1) Convert the given volume from milliliters (mL) to liters (L).

$250 \cancel{\text{mL}}$ x "1 L"/(1000 cancel "mL")# = $\text{0.250 L}$

(2) Convert the given number of Liters to number of moles (mol) using the given molar concentration (unit is moles per Liter solution).

$0.250 \cancel{\text{L}}$ x $\left(0.05 \text{mol")/(1 cancel "L}\right)$ = $\text{0.0125 mol}$

(3) Convert computed number of moles to number of grams (g) using the molecular weight of the substance.

$0.0125 \cancel{\text{mol}}$ x $\frac{180 g}{1 \cancel{\text{mol}}}$ = $\text{2.25 g}$

Therefore, in order to get a 0.05 molar solution, you must dissolve 2.25 grams of glucose in 250 milliliters solvent.

Here is a video that explains in details how to prepare a solution in the lab:
Lab Demonstration | Solution Preparation & Dilution.