Question

What is the molarity of a sodium chloride solution that has 2.0 mol of
sodium chloride dissolved in 0.25 L of water? Answer to two
significant figures.

Answer 1

Answer:

$\boxed {\boxed {\sf 8.0 \ M \ NaCl}}$

Explanation:

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

$molarity= \frac{moles \ of \ solute}{lites \ of \ solution}$

There are 2.0 moles of solute or sodium chloride dissolved in 0.25 liters of water or solution.

• moles of solute = 2.0 mol NaCl
• liters of solution = 0.25 L

Substitute these values into the formula.

$molarity= \frac{ 2.0 \ mol \ NaCl}{0.25 \ L}$

Divide.

$molarity=8 \ mol \ NaCl / L$

Molarity is measured in molars or M. 1 molar is equal to 1 mole per liter, so our answer is equal to 8 molars.

$molarity= 8 \ M \ NaCl$

The original measurements of moles and liters have 2 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. There are no numbers to round, so we add a 0 in the tenths place.

$molarity= 8.0 \ M \ NaCl$

The molarity of the solution is 8.0 M NaCl.