Question

A mass of 100.0 g of NaCl is added to 100.0 mL of water, but not all of it dissolves. A mass of 59.5 grams of NaCl solid remains. Determine the molarity of the dissolved NaCl.

Answer 1

Answer:

The molarity of the dissolved NaCl is 6.93 M

Explanation:

Step 1: Data given

Mass of NaCl = 100.0 grams

Volume of water = 100.0 mL = 0.1 L

Remaining mass NaCl = 59.5 grams

Molar mass NaCl= 58.44 g/mol

Step 2: Calculate the dissolved mass of NaCl

100 - 59. 5 = 40.5 grams

Step 3: Calculate moles

Moles NaCl = 40.5 grams / 58.44 g/mol

Moles NaCl = 0.693 moles

Step 4: Calculate molarity

Molarity = moles / volume

Molarity dissolved NaCl = 0.693 moles / 0.1 L

Molarity dissolved NaCl = 6.93 M

The molarity of the dissolved NaCl is 6.93 M

Answer 2

Answer : The molarity of the dissolved NaCl is, 6.92 M

Explanation : Given,

Total mass of $NaCl$ = 100.0 g

Mass of $NaCl$ remains = 59.5 g

Volume of solution = 100.0 mL

Molar mass of $NaCl$ = 58.5 g/mole

First we have to calculate the mass of dissolved NaCl.

Mass of dissolved NaCl = Total mass of $NaCl$ - Mass of

Mass of dissolved NaCl = 100.0 - 59.5 = 40.5 g

Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.

Formula used :

$\text{Molarity of the dissolved NaCl}=\frac{\text{Mass of }CH_3OH\times 1000}{\text{Molar mass of }CH_3OH\times \text{Volume of solution (in mL)}}$

Now put all the given values in this formula, we get:

$\text{Molarity of the dissolved NaCl}=\frac{40.5g\times 1000}{58.5g/mole\times 100.0mL}=6.92mole/L=6.92M$

Therefore, the molarity of the dissolved NaCl is, 6.92 M