## Molarity Calculations Worksheet Answers

Below are the answers to the molarity calculations worksheet for you to check your work and ensure that you understand the concepts and formulas involved. Molarity is a key concept in chemistry that represents the concentration of a solution and is calculated by dividing the number of moles of solute by the volume of the solution in liters. By practicing molarity calculations, you can improve your understanding and proficiency in this important area of chemistry.

### Problem 1:

Calculate the molarity of a solution that contains 0.5 moles of sodium chloride (NaCl) dissolved in 2 liters of water.

**Answer:** Molarity = moles of solute / liters of solution

Molarity = 0.5 moles / 2 liters = 0.25 M

### Problem 2:

If you have a solution with a molarity of 0.75 M and a volume of 3 liters, how many moles of solute are present?

**Answer:** Moles of solute = Molarity x Volume

Moles of solute = 0.75 M x 3 L = 2.25 moles

### Problem 3:

Determine the volume of a 1.2 M solution that contains 0.6 moles of potassium chloride (KCl).

**Answer:** Volume = moles of solute / molarity

Volume = 0.6 moles / 1.2 M = 0.5 liters

### Problem 4:

If you dilute 500 mL of a 2 M solution of hydrochloric acid (HCl) to a final volume of 2 liters, what is the molarity of the final solution?

**Answer:** M1V1 = M2V2 where M1 is the initial molarity, V1 is the initial volume, M2 is the final molarity, and V2 is the final volume.

(2 M)(0.5 L) = M2(2 L)

M2 = (2 M * 0.5 L) / 2 L = 0.5 M

### Problem 5:

Calculate the molarity of a solution made by dissolving 25 grams of glucose (C6H12O6) in enough water to make 500 mL of solution.

**Answer:** First, convert grams of solute to moles using the molar mass of glucose (180 g/mol). Then, determine the molarity using the formula.

Moles of glucose = 25 g / 180 g/mol = 0.1389 moles

Molarity = 0.1389 moles / 0.5 L = 0.2778 M

### Problem 6:

If you mix 150 mL of a 1.5 M solution of sulfuric acid (H2SO4) with 250 mL of water, what is the molarity of the final solution?

**Answer:** Calculate the moles of solute from both solutions, add them together, and then divide by the total volume to find the molarity of the final solution.

Moles of H2SO4 = (1.5 M)(0.15 L) = 0.225 moles

Final volume = 0.15 L + 0.25 L = 0.4 L

Final molarity = 0.225 moles / 0.4 L = 0.5625 M

### Problem 7:

Determine the volume of a 0.1 M solution of potassium hydroxide (KOH) that contains 0.025 moles of solute.

**Answer:** Use the formula Volume = moles of solute / molarity to find the volume of the solution.

Volume = 0.025 moles / 0.1 M = 0.25 liters = 250 mL

### Problem 8:

If you dilute 100 mL of a 4 M solution of nitric acid (HNO3) to 500 mL, what is the molarity of the final solution?

**Answer:** Use the formula M1V1 = M2V2 to find the final molarity of the solution after dilution.

(4 M)(0.1 L) = M2(0.5 L)

M2 = (4 M * 0.1 L) / 0.5 L = 0.8 M

### Problem 9:

Calculate the molarity of a solution made by dissolving 0.75 moles of magnesium chloride (MgCl2) in enough water to make 2.5 liters of solution.

**Answer:** Use the formula Molarity = moles of solute / liters of solution to find the molarity of the solution.

Molarity = 0.75 moles / 2.5 L = 0.3 M

### Problem 10:

If you have a 0.5 M solution of sodium hydroxide (NaOH) and you need to dilute it to a final volume of 1 liter, what will be the final molarity of the solution?

**Answer:** Use M1V1 = M2V2 to find the final molarity of the solution after dilution.

(0.5 M)(V1) = (1 M)(1 L)

V1 = (1 M * 1 L) / 0.5 M = 2 liters

By practicing these molarity calculations, you can improve your understanding of this important concept in chemistry and become more proficient in solving problems related to solution concentrations. If you need further practice or assistance with molarity calculations, feel free to consult your teacher, tutor, or online resources for additional help.