Question

What is the molarity of a solution containing 9.0 moles of solute in 462 mL of solution

Answer 1

`\boxed {\boxed {\sf 19 \ M}}`

Step-by-step explanation:

Molarity is a measure of concentration in moles per liter, so the formula is:

`molarity= (moles \ of \ solute)/(liters \ of \ solution)}`

This solution has 9.0 moles of solute and 462 milliliters of solution. We must convert milliliters to liters. Remember that 1 liter contains 1000 milliliters.

Create a ratio.

• 
  `( 1 \ L)/( 1000 \ mL)`

Multiply by the value we are converting: 462 milliliters

• 
  `462 \ mL *( 1 \ L)/( 1000 \ mL)`

• 
  `462 *( 1 \ L)/( 1000)`

`0.462 \ L`

Now we know both values and we can solve for the molarity.

• moles of solute= 9.0 moles
• liters of solution = 0.462 L

`molarity= (9.0 \ mol)/( 0.462 \ L)`

Divide.

`molarity= 19.4805195 \ mol/L`

The original measurements of moles and milliliters have 2 and 3 significant figures respectively. We have to round our answer to the least number of sig figs, which is 2 in this case.

For the number we found, that is the ones place. The 4 in the tenths place (19.4805195) tells us to leave the 9 in the ones place.

`molarity= 19 \ mol/L`

1 mole per liter is equal to 1 molar or M, so our answer is equal to 19 M.

`molarity \approx 19 \ M`

The molarity of the solution is approximately 19 M.