Review for Tomorrow’s TestReview for Tomorrow’s Test

MolesMolesStoichiometryStoichiometry

Percent composition Percent composition Empirical FormulaEmpirical Formula

Who is this famous Italian scientist,and what does his number represent?

He is Amadeo Avogadro His number: 6.022 x 1023

There are 6.022 x 1023

molecules of any substance in a mole of that substance

Define what a mole is:

A mole of any substance is __ _________

______ _________ __ _____.

A mole of any substance is its molecular weight expressed in grams

How much does one mole of H2SO4 weigh?

H2SO4

H 2 x 1.0 = 2.0S 1 x 32.1 = 32.1O 4 x 16.0 = 64.0 98.1 grams/mole

How many moles of NaCl are there in 14.65 g ?

Number of grams/mole: Na 1 x 23.0 = 23.0 Cl 1 x 35.5 = 35.5

58.5 g/moleNumber of moles/ liter: 14.65 g x 1 mole = 0.25 moles 58.5 g

Write a balanced equation for the formation of salt

(sodium chloride) from sodium metal and chlorine gas

2 Na (s) + Cl2 (g) 2 NaCl (s)

(This is a combination or synthesis reaction)

How many grams are in 19.3 moles of AlCl3?

How many grams are in 19.3 moles of AlCl3?

19.3 moles x 133.5 g = 2,576.6 g of AlCl3

1 mole

How many moles are in 355.3 grams of Na2SO4?

How many moles are in 355.3 grams of Na2SO4?

355.3 g x 1 moles = 2.5 moles of Na2SO4

142.1 g

How many grams does 1.807 x 1024 molecules of water weigh?

How many grams does 1.807 x 1024 molecules of water weigh?

1.807 x 1024 molecules x 1 mole x 18.0g = 54.0 g 6.02 x 1023molecules 1 mole

How many molecules are in 112 grams of CH4?

How many molecules are in 112 grams of CH4?

112 g x 1 mole x 6.02 x 1023 molecules = 4.214 x 1024

16.0 g 1 mole molecules

Determine the percent composition of Determine the percent composition of

Each element in HEach element in H22SOSO44

Determine the percent composition of Determine the percent composition of

Each element in HEach element in H22SOSO44

H = 2 x 1.0 = 2.0 gS = 1 x 32.1 = 32.1 gO = 4 x 16.0 = 64.0 g

98.1 g/mole

H = 2.0g x 100 = 2.0% 98.1gS = 32.1g x 100 = 32.7% 98.1gO = 64.0g x 100 = 65.2% 98.1g

An unknown compound is found to be An unknown compound is found to be 75% Carbon and 25% Hydrogen 75% Carbon and 25% Hydrogen Determine it’s Empirical FormulaDetermine it’s Empirical Formula(Use a 100 g sample )(Use a 100 g sample )

An unknown compound is found to be An unknown compound is found to be 75% Carbon and 25% Hydrogen 75% Carbon and 25% Hydrogen Determine it’s Empirical FormulaDetermine it’s Empirical Formula(Use a 100 g sample )(Use a 100 g sample )

If there is a 100.0 g sample, then 75.0 g of it is C and 25.0 g of it is H

Carbon: 75.0 g x 1 mole = 6.25 moles 12.0 g

Hydrogen: 25.0 g x 1 mole = 25.0 moles 1.0 g

Find the ratio:6.25 = 16.25

25.0 = 46.25

CH4

HCl + NaHCl + Na22COCO33 CO CO22 + H + H22O + NaClO + NaCl

How many grams of HCl and NaHow many grams of HCl and Na22COCO33 would would

you need to make 35.1 g of salt (NaCl)?you need to make 35.1 g of salt (NaCl)?

35.1 g = 0.6 moles of NaCl. Therefore 0.6 mole of HCl and

0.3 moles of Na2CO3 are needed

HCl needed: 0.6 moles x 36.5 g/mole = 21.9 g

Na2CO3 needed: 0.3 moles x 106 g/mole = 31.8 g

Balance this equation:

Al (s) + O2 (g) Al2O3 (s)

Balanced !

4Al (s) + 3 O2 (g) 2Al2O3 (s)

__Ca + __O2 __CaO

Balance the equation and determine the Molar Ratio needed

between calcium and oxygen?

2Ca + O2 2CaOA 2 to 1 ratio between calcium

& oxygen

Describe what is meant by a

polyatomic ion

A group of atoms that bind together

sharing an ionic charge and acting as one.

What is the sulfate radical and its valence charge?

Sulfate = SO4-2

What is a phosphate polyatomic ion and

what is its valance chargewhen it forms a compound?

Phosphate = PO4-3