# Question #150ce

##### 1 Answer

#### Answer:

You'd need **27 mL** of pure methanol to make that solution.

#### Explanation:

So, you know that you have a stock bottle of liquid methanol. The methanol has a density of **0.793 kg/L**, which means that a 1-L bottle will contain **0.793 kg** of methanol.

To make the calculations easier, convert the density from kg per liter to g per liter

Now, you know that your target solution has a molarity of **0.25 M** and a volume of **2.5 L**. This means that you can determine how many *moles* of methanol the target solution must contain

To determine how many grams of methanol would contain this many moles, use the compound's molar mass

This is how much methanol your target solution must contain. To determine what volume of the pure methanol solution you need to get this many grams, use the given density

Rounded to two sig figs, the number of sig figs you gave for the target solution's volume and molarity, and expressed in mililiters, the answer will be

So, if you take **27 mL** of pure methanol, and add *enough* water to make a total volume of **2.5 L**, you'll end up with a **0.25-M** solution.