Dissolving 120 g of a compound of (mol. wt. 60) in 1000 g of water gave a solution of density 1.12 g/mL. The molarity of the solution is:

First, we need to find the molarity of the solution. Molarity is defined as the number of moles of solute per liter of solution. So, we must calculate two things: the number of moles of the compound and the volume of the solution in liters.

We are given:

• Mass of compound = 120 g
• Molar mass of compound = 60 g/mol
• Mass of water = 1000 g
• Density of solution = 1.12 g/mL

Step 1: Calculate the number of moles of the compound.

Number of moles = mass of compound / molar mass

So, moles = $$ \frac{120 \text{ g}}{60 \text{ g/mol}} = 2 \text{ moles} $$

Step 2: Calculate the total mass of the solution.

The solution is made by dissolving the compound in water, so:

Total mass = mass of compound + mass of water

Total mass = 120 g + 1000 g = 1120 g

Step 3: Calculate the volume of the solution using the density.

Density = mass / volume, so volume = mass / density

Density is given as 1.12 g/mL, and total mass is 1120 g.

Volume in mL = $$ \frac{1120 \text{ g}}{1.12 \text{ g/mL}} $$

To simplify, divide 1120 by 1.12:

$$ \frac{1120}{1.12} = \frac{1120 \times 100}{1.12 \times 100} = \frac{112000}{112} $$

Now, divide 112000 by 112:

$$ 112000 \div 112 = 1000 $$

So, volume = 1000 mL.

Step 4: Convert the volume from milliliters to liters.

Since 1 L = 1000 mL, volume in liters = $$ \frac{1000 \text{ mL}}{1000} = 1 \text{ L} $$

Step 5: Calculate the molarity.

Molarity = moles of solute / volume of solution in liters

Molarity = $$ \frac{2 \text{ moles}}{1 \text{ L}} = 2 \text{ M} $$

Therefore, the molarity of the solution is 2.00 M.

Comparing with the options:

• A. 2.50 M
• B. 1.00 M
• C. 2.00 M
• D. 4.00 M

Hence, the correct answer is Option C.