Calculate the molarity of each

Question

A) 5.00 mole of NaCl in 11.7 L of solution

 

B) 330 mg of NaCl in 1.00 mL of solution

 

Answer 1

Molarity is in units of  mole per liter. (mol/L)

 

 

A) 5.00 mole of NaCl in 11.7 L of solution
 

5.00 mole NaCl / 11.7 L Solution = 5/11.7 = 0.427 M

 

B) 330 mg of NaCl in 1.00 mL of solution
 

Here, you'll need to first convert mg NaCl to mol NaCl using the molar mass of NaCl.

 

Molar mass NaCl = 1(23 g/mol Na) + 1(35 g/mol Cl)

= 58 g/mol NaCl

 

 

330 mg NaCl * 1 g / 1000 mg = 0.330 g NaCl

 

0.330 g NaCl / 58 g/mol NaCl = 0.00569 mol or 5.69 mmol

 

5.69 mmol NaCl / 1 mL solution = 5.69 M NaCl