# Concentrated hydrochloric acid is usually available at a concentration of 37.7 percent by mass. The density of the solution is 1.19 g/mL. What is its molar concentration?

##### 1 Answer

#### Explanation:

As you know, molarity is defined as moles of solute, which in your case will be hydrochloric acid, *liters of solution*.

This means that you can make the calculations easier by picking a

So, use the solution's density to determine what the mass of this

#1.00color(red)(cancel(color(black)("L"))) * (1000color(red)(cancel(color(black)("mL"))))/(1color(red)(cancel(color(black)("L")))) * "1.19 g"/(1color(red)(cancel(color(black)("mL")))) = "1190 g"#

Now, you know that the percent concentration by mass of this solution is equal to **for every**

In this case, your sample would contain

#1190 color(red)(cancel(color(black)("g solution"))) * "37.7 g HCl"/(100color(red)(cancel(color(black)("g solution")))) = "448.63 g HCl"#

All you have to do now is use hydrochloric acid's **molar mass** to find how many moles would be present in

#448.63 color(red)(cancel(color(black)("g"))) * "1 mole HCL"/(36.46color(red)(cancel(color(black)("g")))) = "12.304 moles HCl"#

Therefore, the solution's molarity will be

#color(blue)(c = n/V)#

#c = "12.304 moles"/"1.00 L" = color(green)("12.3 M")#

The answer is rounded to three sig figs.