Exam Review January 2020

Mole Conversions

100

Draw and label the mole map

Mole Map

200

How many molecules of Na2O are in 123.96 grams?

1.2 x 10^24 Na2O molecules

300

How many grams are in 2.15 mole of NaCl?

124.612 grams NaCl

400

How many moles of calcium are in 100.2 grams of calcium?

2.5 moles Calcium

500

How many grams of KCl are in 1.806 x 10^24 formula units ?

221.8 grams KCl

Counting Atoms

100

The number of each type of atom in H2O

What is:

2 Hydrogens

1 Oxygen

200

The number of each kind of atom in NaHCO3

Na=1

H=1

C=1

O=3

300

The number of each kind of atom in Al2(SO4)3

Al=2

S=3

O=12

400

The number of each kind of atom in Ca(C2H3O2)2 

Ca=1

C=4

H=6

O=4

500

The number of each kind of atom in 4 Al2(CO3)3

Al=8

C=12

O=36

Mole Concept

100

Molar Mass is the ________ of all the atomic masses of the elements in compound.

sum

200

One mole of any substance has Avogadro’s number of particles (atoms, ions, molecules, formulas) equal to ____________________________.

6.022 x 10^23 particles

300

One mole of any substance has mass in grams equal to its _______________________.

Molar Mass

400

(T/F) One mole of iron has more atoms than one mole of copper.

False. One mole of iron has 6.022x10^23 iron atoms and one mole of Copper has 6.022x10^23 copper atoms. 

(One mole of any substance, by definition, is equal to 6.022x10^23 particles.)

500

(T/F) One mole of gold and one mole of silver have the same mass.

False. One mole of gold and one mole of silver will have the same number of particles, but each element has a different atomic mass, so their masses are different. 

Percent Composition

100

What is the percent by mass of oxygen in carbon dioxide?

CO2

C=12.011

O2=(2 x 15.999) = 31.998

Molar Mass CO2=(12.011)+(31.998)=44.009

(31.998/44.009) x 100 = 72.7%

200

Find the percent composition of hydrogen in carbon tetrahydride

CH4

C=12.011 g/mol

H4=(4 x 1.008 g/mol) = 4.032 g/mol

Molar Mass CH4=16.04 g/mol

(4.032/16.04) x 100 = 25.14%

300

Find the percent composition of hydrogen in carbon tetrahydride

CH4

C=12.011 g/mol

H4=(4 x 1.008 g/mol) = 4.032 g/mol

Molar Mass CH4=16.04 g/mol

(4.032/16.04) x 100 = 25.14%

400

What is the percent by mass of fluorine in selenium hexafluoride?

SeF6

Se=78.971 g/mol

F6=(6 x 18.998)=113.988 g/mol

Molar Mass SeF6 = 78.971 + 113.988 = 192.959 g/mol

(113.988/192.959) x 100 = 59.07%

500

Consider the compound AlCl3. What is the percent by mass of chlorine?

Al=26.982 g/mol

Cl3=(3 x 35.453 g/mol0=106.359 g/mol

Molar Mass AlCl3 = 26.982 + 106.359 = 133.34 g/mol

(106.389/133.34) x 100 = 79.8%

Molar Mass

100

Calculate the molar mass of carbon dioxide.

CO2

C=12.011 g/mol

O= 15.999 g/mol

Molar Mass = 12.011 + (2 x 15.999) = 44.009 g/mol

200

Calculate the molar mass of acetate (C2H3O2)

C=12.011 g/mol

H=1.008 g/mol

O=12.011 g/mol

Molar Mass =(2 x 12.011 ) + (3 x 1.008) + (2 x 15.999) = 59.044 g/mol

300

Calculate the Molar Mass of Magnesium Chloride

Magnesium has a charge of 2+, chlorine has a charge of 1-. 

MgCl2

Mg=24.305 g/mol

Cl2=35.45 g/mol x 2= 70.9 g/mol

Molar Mass= 24.305 + 70.9 = 95.205 g/mol

400

Calculate the molar mass of Sodium Hydroxide

Na has a charge of +1, Hydroxide has a charge of -1. 

NaOH

Na=22.990 g/mol

O=15.999 g/mol

H=1.008 g/mol

Molar Mass = 22.990+15.999+1.008= 39.997 g/mol

500

Calculate the molar mass of (NH4)2SO4

N=14.007 g/mol x 2 = 28.014 g/mol

H=1.008 g/mol x 8 = 8.064 g/mol

S=32.06 g/mol

O=15.999 g/mol x 4 = 63.996 g/mol

Molar Mass = 28.014 + 8.064 + 32.06 + 63.996 = 132.134 g/mol