What is the molarity of a salt solution made by dissolving 280.0 mg of sodium chloride in 2.00 mL of water? Assume the final volume is the same as the volume of the water.

Answer 1

Amount of NaCl = 280 mg =0.280 g

Molar mass of NaCl = 58.5 g/mole

No. of moles (n) of NaCl = 0.280 g/58.5 g/mole

n = 4.78 x 10^-3mole

Volume of water V = 2.00 mL [1 L =100 mL]

= 0.002 L

Molarity = n /V

= 4.78 x 10^-3mole/ 0.002 L

Molarity = 2.39 M

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