Density of 3M of NaCl is 1.25 g/mL. Calculate the volume of water required to make 1000 mL of this NaCl solution. [Consider the density of water as 1 g/mL]

• A. 1074.5 mL
• B. 1250 mL
• C. 824.5 mL
• D. 1000 mL

To find the volume of water needed to prepare 1000 mL of a 3M NaCl solution with a density of 1.25 g/mL, we first need to calculate the mass of the NaCl solution.

Step 1: Calculate the Mass of the Solution

The formula for mass is:

Mass = Volume × Density

Using the values:

Mass = 1000 mL × 1.25 g/mL = 1250 g

Step 2: Calculate the Mass of NaCl in the Solution

Next, we need to find out how much NaCl is in the solution. The molarity (M) is defined as:

Molarity = Moles of solute / Volume of solution in liters

For a 3M solution:

3 moles/L × 1 L = 3 moles of NaCl

The molar mass of NaCl is approximately 58.44 g/mol. Therefore, the mass of NaCl is:

Mass of NaCl = 3 moles × 58.44 g/mol = 175.32 g

Step 3: Calculate the Mass of Water

Now, we can find the mass of water in the solution:

Mass of water = Total mass of solution - Mass of NaCl

Mass of water = 1250 g - 175.32 g = 1074.68 g

Step 4: Convert Mass of Water to Volume

Since the density of water is 1 g/mL, the volume of water can be calculated as:

Volume of water = Mass of water / Density of water

Volume of water = 1074.68 g / 1 g/mL = 1074.68 mL

Final Answer

Rounding to one decimal place, the volume of water required is approximately 1074.5 mL.

The correct option is: A. 1074.5 mL