Molarity Problems Worksheet Answer Key: Chemistry Made Easy

Molarity Problems Worksheet Answer Key: Chemistry Made Easy

Chemistry problems can be challenging, but with the right approach, they can be solved with ease. In this article, we will provide a comprehensive answer key to common molarity problems, making chemistry easier for students and educators alike.

What is Molarity?

Before we dive into the answer key, let’s quickly review what molarity is. Molarity is a measure of the concentration of a solution, expressed as the number of moles of solute per liter of solution. It’s a fundamental concept in chemistry, and understanding it is crucial for solving various problems.

Molarity Problems Worksheet Answer Key

Here are some common molarity problems, along with their solutions:

Problem 1: A 250 mL solution contains 15 g of NaCl. What is the molarity of the solution?

Answer:

First, we need to find the number of moles of NaCl:

moles NaCl = mass NaCl / molar mass NaCl moles NaCl = 15 g / 58.44 g/mol moles NaCl = 0.257 mol

Next, we need to find the volume of the solution in liters:

V = 250 mL / 1000 mL/L V = 0.25 L

Now, we can calculate the molarity:

Molarity = moles NaCl / V Molarity = 0.257 mol / 0.25 L Molarity = 1.03 M

Problem 2: A 1.5 M solution of HCl has a volume of 500 mL. How many moles of HCl are present in the solution?

Answer:

We can use the formula:

moles HCl = Molarity x V moles HCl = 1.5 M x 0.5 L moles HCl = 0.75 mol

Problem 3: A solution contains 25 g of glucose (C6H12O6) in 1000 mL of water. What is the molarity of the solution?

Answer:

First, we need to find the number of moles of glucose:

moles glucose = mass glucose / molar mass glucose moles glucose = 25 g / 180.16 g/mol moles glucose = 0.139 mol

Next, we need to find the volume of the solution in liters:

V = 1000 mL / 1000 mL/L V = 1 L

Now, we can calculate the molarity:

Molarity = moles glucose / V Molarity = 0.139 mol / 1 L Molarity = 0.139 M

Problem 4: A 2 M solution of NaOH has a volume of 200 mL. How many grams of NaOH are present in the solution?

Answer:

We can use the formula:

moles NaOH = Molarity x V moles NaOH = 2 M x 0.2 L moles NaOH = 0.4 mol

Next, we can find the mass of NaOH:

mass NaOH = moles NaOH x molar mass NaOH mass NaOH = 0.4 mol x 40 g/mol mass NaOH = 16 g

Table: Molarity Problems and Answers

Here’s a table summarizing the problems and answers:

📝 Note: Make sure to check the units of the given values and the answer to ensure accuracy.

By following these steps and using the formulas, you’ll be able to solve molarity problems with ease. Remember to always check your units and calculations to ensure accuracy.