Investigation 3:

Lesson 1:Molarity!

© 2004 Key Curriculum Press.

Unit IV • Investigation II-X

Admit Slip

• Drinking water in our homes contains dissolved chlorine, a highly toxic substance.

Why can we drink the water?

© 2004 Key Curriculum Press.

Unit IV • Investigation II-X

Today’s ObjectivesStudents will be able to:• Define molarity as a concentration• Calculate molarity given moles of the solute

and volume of the solvent.

© 2004 Key Curriculum Press.

AgendaAdmit SlipHomework CheckNotes

Product: Notes, Exit Slip

Unit IV • Investigation II-X

© 2004 Key Curriculum Press.

Unit IV • Investigation II-X

Solutions and Molarity 4 / 30 / 14

• A solution is a homogeneous mixture of two or more substances that is uniform

throughout. • The substance in the greater amount (often a liquid) is called the solvent. • The solute is usually a solid and dissolved in the solvent. • Concentration is the amount of solute for a specified amount of solvent.

© 2004 Key Curriculum Press.

Unit IV • Investigation II-X

• A common measure of concentration is moles per liter, mol/L, which is referred to as molarity, M.

• If a solution is highly concentrated, it has a lot of solute per solvent and a high molarity.

• If a solution is not very concentrated (dilute), it has only a little solute per solvent and a low molarity.

© 2004 Key Curriculum Press.

Unit IV • Investigation II-X

• To calculate molarity from moles and volume, you divide moles by volume in liters.

• If you have 2 moles and 5 L of solution, you have

• If you are given grams of solute, you need to divide by molar mass to calculate moles before calculating molarity.

LmolM

MLmol 4.05

2

© 2004 Key Curriculum Press.

Unit IV • Investigation II-X

• If you are given volume in milliliters, mL, you move the decimal 3 times to get the volume in liters.

50 mL = 0.050 L

• To calculate moles from molarity and volume, you multiply them.

Since , M * L = molesLmolM

© 2004 Key Curriculum Press.

Exit SlipWhat is the concentration of a solution with 10 mol of sugar and a volume of 4 L?

Unit IV • Investigation II-X