Unit 4 cp the molef

Unit 4 The Mole

Unit 4 Measuring Matter

Warm-Up

Identify terms we use everyday that describe a quantity. (at least 3)

Warm-Up

What is the common meaning of a mole?

What is the scientific meaning of a mole?

Counting particles

Do you ask for 12? Do you ask for 24?OR do you ask for a DOZEN???

Much easier for the product we are buying if it is sold in UNITS.

The Mole is…Abbreviated molSI unit, used to measure the

amount of a substanceDefined as the number of

carbon atoms in exactly 12 g of pure carbon-12

Common meaning

A small burrowing animal.

The damage to the lawn was caused by a mole.

Scientific meaningAn SI base unit used to measure the quantity of matter.

The chemist measured out a mole of the compound.

Avogadro’s NumberThe number

6.0221367 x 10 23

Avogadro was a Italian physicist.

Avogadro’s Number

Avogadro's number is rounded to three significant figures.

Is used to measure extremely small particle such as atoms.

Converting between Moles and ParticlesSuppose you buy 3 ½ dozen of

roses and you want to know how many roses you have.

Example Calculation (Work problem out)

Describe how you can tell if the wrong conversion factors has been used.

Moles to particles

How many particles are in 3.50 mol of

sucrose?

Reinforcement Problems

1. Zinc (Zn) is used to form a corrosion-inhibiting surface on galvanized steel. Determine the number of Zinc atoms in 2.50 mol Zn?

2. Calculate the number of molecules in 11.5 mol of water (H2O).

3. Challenge Calculate the number of oxygen atom in 5.0 mol of oxygen molecules. Oxygen is a diatomic molecule O2

Particles to MolesYou can convert between moles and

number of representative particles by multiplying the known quantity by the proper conversion factor.

ReinforcementHow many moles are in each of the following?

a. 5.75 x 1024 atoms Al

b. 2.50 x 1024 atoms Fe

Unit 4 Measuring matter worksheet

Unit 4 Mass and the Mole

Calculate the number of molecules in 5.67 mol of water (H2O).

Mass and the MoleA mole always contain the same

number of particles; however, moles of different substances have different masses.

Real world application You would not expect a dozen limes to

have the same mass as a dozen eggs.

WHY? Eggs and Limes differ in size and

composition.One mole quantities has different masses for

the same reasons.

Molar Mass

The atomic weight of and element expressed in

grams is the mass of one mole of that element.

Unit g/mol

Apply

What of the mass of one mole of copper?

63.546 g

Using molar mass-Real World Application Imagine that we buy jelly beans

bulk, and sell them by the dozen. We soon realize that counting out a dozen or 10 dozen every time someone orders some is to much work, What can we do instead?

Using molar mass-Real World Application

The mass of…

1 dozen Jelly Beans = 35 g of Jelly Beans

Conversion Factors= ??

Using molar mass-Real World Application

What mass of Jelly beans would you measure if a

customer want 5 dozen jelly beans?

175 g Jelly beans

Moles to MassSuppose you need to measure

out 3.00 mol of copper (Cu).

How would you measure that amount?

191 g Cu

Suppose you want to go grams back to moles?

Mole-to-Mass Conversion1. Determine the mass in grams of each

of the following.a. 3.57 mol Alb. 42.6 mol Si

2. Challenge Convert each given quantity in scientific notation to mass in grams expressed in scientific notation.

a. 3.45 x 102 mol Cob. 2.45 x 10-2 mol Zn

Mass-to-Mole

1. Determine the number of moles in each of the following.

a. 25.5 g Agb. 300.0 g S

Unit 4 Mass and the Mole Mass-to-atoms

Converting between mass and atoms

Back to the jellybean example… at the end of the day you have 550 g of jelly beans left over, how many jelly beans is that?

Remember 35 g= 1 dozen

Steps to follow

1. grams of jelly beans dozens of jelly beans

2. Dozens of jelly beans # of jelly beans

Reinforcement

Mass to atoms/ Atoms to mass Worksheet

Unit 4 Re-cap

ActivityOn a blank sheet of

computer paper design a concept map, outlining the conversion between mass,

moles, and particles

Warm-Up

Calculate the mass of 0.25 mol of carbon-12

Unit 4 Moles of a compound

Chemical Formulas & The MOLEChemical formula=indicates the

number and types of atoms contained in one unit of the compound.

InterpretHow many of each kind of

atom- carbon, chlorine, and fluorine-are contained in 1 mol of CCl2F2 ?

C=1Cl=2F=2

Interpret

How many moles of F are in 5.50 of freon (CCl2F2 ) ?

11.0 mol F atoms

Molar mass of Compounds

Calculate the molar mass of K2CrO4.

194.20 g

Reinforcement 1. Determine the molar mass of each ionic

compound.a. NaOHb. CaCl2c. KC2H3O2

2. Calculate the molar mass of each molecular compound.

a. C2H5OH

b. HCN

Converting Moles to mass

How many grams of F are in 11.0 mol F ?

Conversion Factors Conversion factors map

Unit 4 Measuring matter Lab

Warm-UpSuppose a student measured out

8.91 g of Al2O3 Aluminum oxide… (answer the following)Molar mass of Al2O3

Moles of compoundMoles of each elementAtoms of each element

Warm-UpSuppose a student measured out

81.2 g of CaCO3 Calcium Carbonate… (answer the following)Molar mass of Moles of compoundMoles of each elementAtoms of each element

Warm-UpSuppose a student measured out

81.2 g of CaCO3 Calcium Carbonate… (answer the following)Molar mass of Moles of compoundMoles of each element

Measuring Matter LabSafety- goggles, glovesProper use of equipmentProcedureExpectation –Clean Lab area Questions?

After LabComplete analysisWork on review/homework

packetStudy for Quiz

Unit 4 Chalk Lab

Warm-Up

Find the molar mass of calcium carbonate (CaCO3)

Lab Expectations

Find the following…How many moles of chalkHow many mole of Ca… How many

atomsHow many moles of C… How many

atomsHow many moles of O… How many

atoms

Lab Procedure

Find mass before-recordFind mass after-recordFind molar massDetermine the number of mole required

Unit 4 Mole & the volume

Warm-Up

How much does 4.2 moles of Ca(NO3)2 weigh?

Quiz

Unit 4 Mole & the volume

Moles to Volume In the calculations, some questions should use conversions more than once; however, mole is in the center , because all conversions between mass, particles and volume should be converted to moles at first.

Moles and volume

Unit 4 Empirical and Molecular formulas

Real World Application You might have noticed that some food

containers contain two or more serving instead of the single serving you would expect. How would you determine the total number of calories contained in the package?

Real World Application What do you do??

Percent by massPercent by mass: the ratio of

the mass of each element to the total mass of compound expressed as a percent.

Percent CompositionPercent by mass (element) =

mass of element --------------------------

X100 = mass of compound

Sample Problem You have a 100g sample of a compound

that contain 55 g of element X and 45g of element Y.

The compound is 55% X and 45% Y

The percent composition from the Chemical Formula

Percent by mass= mass of element in 1 mol of compound

-------------------------------------------------------------------- X 100

molar mass of compound

Unit 4 Empirical formula from mass composition

Empirical formula IS THE FORMULA WITH THE SMALLEST

WHOLE-NUMBER MOLE RATIO OF THE ELEMENTS.

The empirical formula might or might not be the same as the actual molecular formula, of different the molecular formula will be a simple multiple of the empirical formula.

Empirical formula For example:

Hydrogen peroxide

Empirical formula= HOMolecular formula= H2O2

How do you find empirical formula? Percent composition or masses of the

elements in a given mass of compound

List the steps needed to calculate the empirical formula from percent composition data…

1. Assume that the total mass of the compound is 100.00 g the percent by mass of each element is equal to the mass of each element in grams

2. Convert the mass of each element to moles using the molar mass as a conversion factor.

List the steps needed to calculate the empirical formula from percent composition data…

3. Divide each molar amount by the smallest mole value

4. If needed multiply each by an interger to determine the smallest whole-number ratio

5. Write the empirical formula using the smallest whole-number ratio.

Reinforcement Empirical formula from percent composition

Methyl acetate is a solvent commonly used in some paints, inks, and adhesives. Determine the empirical formula for methyl acetate, which has the following chemical analysis:

48.64% carbon 8.16% hydrogen 43.20% Oxygen

1. Assume that each percent by mass represents the mass of the element in 100g sample, the percent sign CAN BE REPLACED WITH GRAMs(g).

2. Convert each mass to moles using conversion factors (inverse molar mass- that relates moles to grams)

3. Calculate the simplest ratio of moles of elements by dividing the moles of each element by the SMALLEST value in the calculated mole ratio.

4. Multiply each number in the ratio by the SMALLEST number

Reinforcement Empirical formula from percent composition

Methyl acetate is a solvent commonly used in some paints, inks, and adhesives. Determine the empirical formula for methyl acetate, which has the following chemical analysis:

48.64% carbon 8.16% hydrogen 43.20% Oxygen

Unit 4 Molecular formula

Molecular formula Specifies the actual number of atoms of

each element in one molecular formula unit of the substance