Molarity

Agenda

Review

Notes on Molarity

Practice molarity

NaBr + F2 NaF + Br2

What type of reaction?

How many spectator ions?

What is the spectator ion?

What is the net ionic equation?

Steps for Stoichiometry

Into moles

Mole ratio

Out of moles

What does concentrated mean?

What is a solvent?

Molarity

Date:

Molarity

Definition: moles of solute dissolved per one liter of solution.

moles

LiterMolarity

Solute: substance being dissolved

Solvent: substance doing the dissolving.

Units are mol/L or MCalled molar

With nail polish and nail polish remover, which is the solvent and which is the solute?

What about with kool-aid?

Relation to Mole TownAdd a new town between the Valley of Volume and DC.

Do not cross the STP dateline to get to the Molehills of Molarity.

When you leave Mole Town DIVIDE, by the volume in liters.

To return to Mole Town, MULTIPLY by the volume in liters.

MOLE TOWN

MASS

MO

LE

TIP

LY

DIVID

E

MOLAR MASS

MOLETIPLY

DIVIDE6.02*1023 RP/mol

DC

STP Dateline

MOLETIPLY

DIVIDE

22.4 L/mol

VALLEY

MOLE HILLS OF MOLARITY

DIVIDE

LITERS

Hints

ALWAYS start problems with single unit

Remember that Molarity is a derived unit – two units put together.

Separate Molarity into moles and liters, putting only one unit in each box of the bridge.

When 3.0 moles of NaCl are dissolved in 1.0 L of H2O, what is the molarity?

= 3.0 M NaCl3.0 mol NaCl

1.0 L NaCl

MT

This box is empty

– get it MT!

Don’t use H2O, switch to compound being dissolved

When 2.0 moles of NaCl are dissolved in 0.50 L of H2O, what is the molarity?

4.0 M

When 5.0 moles of NaCl are dissolved in 2.5 L of H2O, what is the molarity?

2.0 M

When 2.0 moles of NaCl are dissolved in 100. mL of H2O, what is the molarity?

0.20 M

When 0.50 moles of NaCl are dissolved in 50. mL of H2O, what is the molarity?

10. M

When 5.8 grams of NaCl are dissolved in 100. mL of H2O, what is the molarity?

1.0 M

When 2.9 grams of NaCl are dissolved in 50. mL of H2O, what is the molarity?

1.0 M

DilutionWhat does it mean to you if something is diluted?

Dilution is changing the molarity by adding or removing some of the solvent. Note, the number of moles remains constant.

M1V1 = M2V2

You are given a solution of 14.8 M NH3. How many milliliters of this solution do you require to give 100.0 mL of 1.00 M NH3 when diluted?

6.76 mL

You have a solution that is 1.5 M H2SO4. How many milliliters of this acid do you need to prepare 100.0 mL of 0.18 M H2SO4?

12 mL

You wish to prepare 0.12 M HNO3 from a stock solution of nitric acid that is 15.8 M. How many milliliters of the stock solution do you require to make up 1.00 L of 0.12 M HNO3?

7.6 mL

A chemist want to prepare 0.250 M HCl. Commercial hydrochloric acid is 12.4 M. How many milliliters of the commerical acid does the chemist require to make up 1.50 L of the dilute acid?

30.2 mL

A chemist needs to create 500 mL of 0.5 M HCl from 5.0 M HCl. How much water must the chemist add to complete the dilution?

450 mL of water

Homework

Complete the 10 questions on the provided worksheet.