NAME___Key______________________________________________  DATE _________________

 

UNIT 5 Review Sheet (Chapters 7,8)

Answer the following Questions in pencil

PART I – Questions

 

1. What kind of visual evidence indicates that a chemical reaction has taken place?

color change, bubbles form, energy or heat being given off or absorbed, precipitate formation

 

2. What are the substances indicated to the left of the arrow in a chemical reaction?  To the right?

 substances to the left of the arrow are the reactants

substances to the right of the arrow are the products

 

3. How are the physical states of the substances indicated when writing a chemical reaction?  Give all of the examples used in class.

s- solid, g-gas, l-liquid, aq- aqueous, ppt - precipitate

 

4. What does it mean to “balance” a chemical reaction?

equal number of atoms of each element on both the reactants and products side

 

5. What is a precipitation reaction?  Give an example.

A precipitate forms as the product of a chemical reaction.

example from lab – double replacement- NaCl(aq) + AgNO3 (aq) à NaNO3 (aq) + AgCl (ppt)

 

6. What is a combustion reaction?  Give an example.

Hydrocarbon reacts with oxygen to form carbon dioxide, water, and energy

CH3 + O2 à CO2 + H2O + energy

 

7. In general terms, what are the “spectator ions” in a precipitation reaction?

not on this test

 

 

 

PART II– Balance the following chemical reactions and indicate the TYPE of reaction

8.             __1_Pb(NO3)2 + __1_K2CrO4 à __1__PbCrO4 + __2__KNO3

9.             ___1_Cl2 + __2__KI à __2__KCl + __1__I2

10.           __2__C3H6 + __9__O2 à __6__CO2 + __6__H2O

11.           ___2__Al(OH)3 à __1__Al2O3 + __3__H2O

12.           __4__Li + __1__O2 à __2__Li2O

 

PART III – Write and balance a chemical reaction based on the following sentences

 

13. Bromine gas reacts with a solution of potassium chloride to produce chlorine gas and potassium bromide

 

Br2 + 2KCl à 2KBr + Cl2

 

14. Hydrogen gas and iron(III) chloride are produced when solid iron is dropped into hydrochloric acid (HCl).

 

2Fe + 6HCl à 2FeCl3 + 3H2

 

15. Solid tetraphosphorus decaoxide reacts with water to produce phosphoric acid (H3PO4).

 

P4O10 + 6H2O à 4H3PO4

 

16. Silver (I) acetate and hydrochloric acid solutions combine to form a silver (I) chloride precipitate and an acetic acid solution (HC2H3O2). 

 

Ag(C2H3O2)  + HCl à AgCl + HC2H3O2