chapter 7 notes, part i - schools.misd.orgschools.misd.org/upload/template/6094/chemistry notes one...

Chemistry Notes

What is a mole?

One Step Problems

A Mole...

A mole is a unit of

measurement that tells how

many particles of something

you have!

1 mole = 6.02 x 1023 particles

What are particles?

Particles could be anything,

but because of the size of the

number, we usually mean

atoms, molecules or formula

units.

Avogadro’s Number

The number 6.02 x 1023 is

called Avogadro’s number.

Practice Problem #1

How many moles are in

2.57 x 1025 atoms He?

Practice Problem #1

How many moles are in

2.57 x 1025 atoms He?

2.57 x 1025 atoms He x 1 mole He = 42.7 moles He

6.02 x 1023 atoms He

Practice Problem #2

How many molecules of CO2

are in 25.3 moles?

Practice Problem #2

How many molecules of CO2 are

in 25.3 moles?

25.3 moles CO2 x 6.02 x 1023 molecules CO2 = 1.52 x 1025 molecules

1 mole CO2

Moles and Volume

1 mole of all gases at a certain set

of conditions called STP

(standard temperature and

pressure) have the same

volume: 22.4L

So, 1 mole = 22.4L (gas @ STP)

Practice Problem #3

How many moles of O2 are in

29.3L of O2 gas?

Practice Problem #3

How many moles of O2 are in

29.3L of O2 gas?

29.3 L O2 x 1 mole O2 = 1.31 moles O2

22.4 L O2

Practice Problem #4

If you have 3.6 moles of N2O

(Nitrous oxide) how many liters

would you have?

Practice Problem #4

If you have 3.6 moles of N2O

(Nitrous oxide) how many

liters would you have?

3.6 moles N2O x 22.4 L N2O = 81 L N2O

1 mole N2O

Mass and Moles

How do we usually measure

out chemicals in a lab?

We usually use mass to

measure out chemicals.

Mass and Moles

The problem with mass is that

not all atoms or compounds

have the same mass.

Mass and Moles

Avogadro’s number was

established by using Carbon-

12 as a standard. The

number of particles in 12

grams of carbon 12 was set as

1 mole.

Mass and Moles

The atomic mass on the

periodic table is also an

element’s molar mass (the

mass of one mole of an

element, measured in

g/mol).

What is the molar mass of...


He


He 4.0026 g/mol


He 4.0026 g/mol

Al


He 4.0026 g/mol

Al 26.982 g/mol


He 4.0026 g/mol

Al 26.982 g/mol

Ba


He 4.0026 g/mol

Al 26.982 g/mol

Ba 137.327 g/mol


He 4.0026 g/mol

Al 26.982 g/mol

Ba 137.327 g/mol

Rn


He 4.0026 g/mol

Al 26.982 g/mol

Ba 137.327 g/mol

Rn 222 g/mol

Furthermore...

Since compounds are just atoms bonded together, you can find the molar mass of a compound by adding together the molar mass of all the elements in the compound.


NaCl


NaCl 58.443 g/mol


NaCl 58.443 g/mol

CO2


NaCl 58.443 g/mol

CO2 44.009 g/mol


NaCl 58.443 g/mol

CO2 44.009 g/mol

Be3N2


NaCl 58.443 g/mol

CO2 44.009 g/mol

Be3N2 55.0506 g/mol


NaCl 58.443 g/mol

CO2 44.009 g/mol

Be3N2 55.0506 g/mol

Ca(NO3)2


NaCl 58.443 g/mol

CO2 44.009 g/mol

Be3N2 55.0506 g/mol

Ca(NO3)2 164.088 g/mol

Practice Problem #5

How many grams of iron are

in 3.5 moles?

Practice Problem #5

How many grams of iron are

in 3.5 moles?

3.5 moles Fe x 55.847 g Fe = 195.5 g Fe

1 mole Fe

Practice Problem #6

How many moles of Na2O are

in 355.1g?

Practice Problem #6

How many moles of Na2O are

in 355.1g?

355.1 g Na2O x 1 mole Na2O = 5.73 mol Na2O

61.979 g Na2O

chapter 7 notes, part i - schools.misd.orgschools.misd.org/upload/template/6094/chemistry notes one...

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