Chem unit 3

Question 1

Law of Conservation of Mass

Answer 1

mass is not created/destroyed during ordinary chemical reaction/physical changes

Question 2

Law of Definite Proportions

Answer 2

chemical compound contains same elements in same proportion by mass regardless of size of sample/compound

Question 3

Law of Multiple Proportion

Answer 3

If 2+ diff compounds are composed of same 2 elements, the ratio of masses is always small whole #

Question 4

Chem rxn

Answer 4

1+ substance changes to new substance

Question 5

Indications of chem rxn

Answer 5

change in temp,

production of light, production of gas, production of precipitate, color change

Question 6

Factors affecting rxn rate

Answer 6

nature of reactants, concentration, surface area, temp, presence of catalyst/inhibitor

Question 7

Symbols

Answer 7

(s): solid
(l): liquid
(g): gas
(aq): aqueous
triangle on yield: heat is added (faster)
arrow up: gas produce
arrow down/(ppt): precipitate
pt on yield: platinum catalyst is add

Question 8

Types of rxn

Answer 8

S: A+B-AB
D: AB-A+B
SR/D: A+BC-AC+B
DR/D: AB+CD-AD+CB
combustion: CH+O2-CO2+H2O

Question 9

Assigning oxidation #

Answer 9

pure element: 0
Hydrogen: +1 (except when bonded w/ metal)
Oxygen: -2 (except 4: H202) OXIDATION # SHOULD CANCEL OUT FOR EACH POLYATOMIC ION

Question 10

Oxidation vs reduction

Answer 10

o: increase oxygen/more positivity,

r: decrease in oxygen, become negative

Question 11

Redox

Answer 11

1. assign oxidation #
2. identify where reduction/oxidation occur
3. write half reaction
4. balance only elements
5. balance oxygen, add H20
6. balance hydrogen, add H+
7. add electron to more positive side
8. multiply equation to cancel out electrons
9. subtract like compounds
10. combine half reaction

Question 12

Solubility Guidelines

Answer 12

1. Chlorates, acetates, nitrates, nitrites, and perchlorates are soluble.
2. Sulfates are soluble except those of calcium, strontium, barium, mercury, redium, lead, and silver.