# Question #42082

##### 1 Answer

You'd need **250. mL** of your solution to get that many moles of hydrochloric acid.

As you know, molarity is defined as moles of solute, in your case hydrochloric acid, divided by liters of solution.

This means that, if you get **1 mole** of something in **1 L** of solution you'll get a **1 M** solution.

Let's play a little with this concept. By the same reasoning, if you get **12 moles** of **12 L** of solution, you'll once again have a **1 M** solution.

Now let's say you get **12 moles** of **1 L** of solution. You'd have the same number of moles as in the previous case, but now the volume is *12 times smaller**12 times higher*, so you'd get a **12 M** solution.

If you start with **3 moles** of **1 L** to get a **3-M** solution. If you want to keep the number of mole constant and *increase* the molarity, you'll have to *decrease* the volume.

THis means that, to get a molarity that's *4 times bigger*, you need a volume *4 times smaller*. Automatically, this means that you'd need **250. mL**, or **1/4th** of aliter, to get a **12 M** solution with **3 moles** of solute.

For more complex calculations, you'll have to use the formula for molarity

In this case, you'd get

Expressed in mL, the answer will be