Chemical Reactions and Equations Assessment Study Guide

Question 1

What is an empirical formula?

Answer 1

An empirical formula is the simplest form of whole number. For example SO2 empirical formula would be SO

Question 2

What is a molecular formula?

Answer 2

A molecular formula tells us how many of each type of atom are present in a molecule. For example the molecular formula of water is H2O this shows that there is one hydrogen and two oxygen atoms

Question 3

What are diatomic elements?

Answer 3

Diatomic elements are molecules that only have two atoms.

Question 4

Which elements are diatomic?

Answer 4

The seven diatomic elements are hydrogen, nitrogen,oxygen,Fluorine,chlorine,bromine,and iodine.

Question 5

Turn the following molecular formulas into empirical formulas:
a. C6H12O6
b. C4H10
c. C2H4N2

Answer 5

a. C6H12O6 (CHO)
b. C4H10 (CH)
c. C2H4N2 (CHN)

Question 6

What is the law of conservation of matter? What needs to be the same amount on both sides of the chemical equation?

Answer 6

The law of conservation of matter starts that in chemical reactions the total mass of the products must equal the total mass of the reactants.

Question 7

What are reactants and what are products? How can you tell whether a substance is a reactant or a product?

Answer 7

The Substances that go in a chemical reaction are called reactants and the products are the substances produced at the end of a chemical reaction.

Question 8

Calculate the mass of 0.50 moles Mg3(PO4)2.

Answer 8

131.35

Question 9

How many moles are in 22.5 grams of Al2O3?

Answer 9

0.22

Question 10

Determine the percent composition of each element in Na2SO4.

Answer 10

Na-32.3%
S-22.6%
O-45.1%

Question 11

A compound is 15.8% carbon and 82.4% sulfur. What is the empirical formula of the molecule?

Answer 11

CS2

Question 12

A 15.67 g sample of a hydrate of magnesium carbonate was heated, without decomposing the carbonate, to drive off the water. The mass was reduced to 7.58 g. What is the percentage of water in the hydrate?

Answer 12

51.6

Question 13

Balance the following chemical equations:
____8CH2O + _____4O2 → _____8CO2 + _____8H2O

Answer 13

____CH2O + _____O2 → _____CO2 + _____H2O

Question 14

_____2MgO → _____2Mg + _____ O2

Answer 14

_____MgO → _____Mg + _____ O2

Question 15

_____ C3H8 + ____4O2 → _____4CO2 + _____8H2O

Answer 15

_____ C3H8 + ____O2 → _____CO2 + _____H2O

Question 16

_____ CaCl2 + _____ KOH → _____ KCl + _____ Ca(OH)2

Answer 16

_____ CaCl2 + _____ KOH → _____ KCl + _____ Ca(OH)2

Question 17

____4Al + _____6H2S → _____2Al2S3 + ___6H2

Answer 17

____Al + _____H2S → _____Al2S3 + ___H2

Question 18

_____4NaCl + ____2Fe(SO4) → _____2Na2SO4 + ____2 FeCl2

Answer 18

_____NaCl + ____Fe(SO4) → _____Na2SO4 + ____FeCl2

Question 19

_____ S8 + _____12O2 → _____8SO3

Answer 19

_____ S8 + _____O2 → _____SO3

Question 20

What are the key reactants and products of combustion?

Answer 20

Hydrocarbon and oxygen are the reactants and the products are h20 and carbon dioxide

Question 21

What are the products of KI + Pb(NO3)2, a double displacement reaction?

Answer 21

KI + Pb(NO3)2->2kNO3+PbI2

Question 22

What are the products of Zn(II) + HCl, a single displacement reaction?

Answer 22

Zn(II) + HCl -> ZnCl2+H2