Molarity Lesson

Molarity

Today we will be figuring out how to use concentration

Multiple Choice

The total number of moles represented by 20 grams of CaCO3 (gram formula mass = 100 g/mol) is:

Determine the mass given.

• 20 grams

• 100 g/mol

• unknown

Multiple Choice

The total number of moles represented by 20 grams of CaCO3 (gram formula mass = 100 g/mol) is:

Determine the gram formula mass.

• 20 grams

• 100 g/mol

• unknown

Multiple Choice

The total number of moles represented by 20 grams of CaCO3 (gram formula mass = 100 g/mol) is:

What is the unknown?

• mass

• gram formula mass

• moles

Open Ended

The total number of moles represented by 20 grams of CaCO3 (gram formula mass = 100 g/mol) is:

Remember from previous problems:

mass = 20 grams

gfm = 100 g/mol

moles = moles

moles = mass/gfm

What is concentration?

The amount of a substance in a given space.

The picture on the left has a greater concentration than the picture on the right because there are more particles in the same amount of space.

Molarity

A way to measure concentration.

the concentration of a solution expressed in the number of moles per liter of solution.

The unit is Molarity (M)

Sample Problem 1

• Determine the molarity of 0.500 L of a solution with 0.35 mol of dissolved solute.

• How do we determine the variables?

• moles of solute always has the unit mol.

• Liters of solution always has the unit L

• Molarity always has the unit M

Sample Problem #2

• How many moles of MgSO4 are contained in 0.05 L of a 3.0 M solution?

• How do we determine the variables?

• moles of solution always has the unit of mol

• Liters of solution always has the unit of L

• Molarity always has the unit M

Multiple Choice

What is the molarity of a 3 L solution containing 6 moles of NaCl?

Determine the molarity.

• 3 L

• 6 mol

• unknown

Multiple Choice

What is the molarity of a 3 L solution containing 6 moles of NaCl?

Determine the number of moles.

• 3 L

• 6 mol

• unknown

Multiple Choice

What is the molarity of a 3 L solution containing 6 moles of NaCl?

Determine the Liters of Solution.

• 3 L

• 6 mol

• unknown

Open Ended

What is the molarity of a 3 L solution containing 6 moles of NaCl?

Remember:

Molarity (M) = unknown

moles = 6 mol

Liters = 3 L