unit 7

Question 1

what is the law of conservation of mass?

Answer 1

in an enclosed system, matter cannot be created or destroyed

Question 2

what is a chemical formula

Answer 2

a mole ratio of elements in a compound

Question 3

what 2 things does a coeff. represent

Answer 3

number of atoms involved in a reaction
number of moles of the substance needed in a reaction

Question 4

why do thes sum of the particles have to be the same

Answer 4

bc there must be the same number of particles for each element on both sides so totals will be the same

Question 5

observable evidences of a chemical change

Answer 5

pH change, color change, change in flaming splint, pop noises

Question 6

practice balancing equations also
if a compound is ionic what do u do first

Answer 6

balance charges
find the charge of both elements and switch them

Question 7

synthesis

Answer 7

one product

Question 8

decomposition

Answer 8

one reactant

Question 9

single replacment

Answer 9

metal replacing cation in a compound
halogen replacing halogen (g17)

Question 10

double replacment

Answer 10

compound + compound -) compound + compound

cations swap places

Question 11

combustion

Answer 11

hydrocarbon + O2 -) CO2 + H2O

Question 12

reduction

Answer 12

gaining electrons

Question 13

oxidation

Answer 13

losing electrons

Question 14

REDOX rules

Answer 14

elements=0
h=+1
f=-1
O=-2 (unless with F)
Halogen=-1 (O or F)
Group 16 = -2(O, F, or halogen)
Group 15 = -3 (unless with above)

elemtns can just be number too

Question 15

percent yeild

Answer 15

a comparison of what is produced to what should be

experimental / theoretical x 100

Question 16

experimental yeild

Answer 16

amount of product that is actually produced IS

Question 17

theoretical yeild

Answer 17

amount of product that should be produced SHOULD

Question 18

when it is a triangl H problem finding the energy what are the steps

Answer 18

grams to mols, mols to KJ
vice versa
KJ to mols, mols to grams

Question 19

for litre equations what are steps

Answer 19

grams to mols, moles to moles, moles to Liters (treat as grams same set up)

Question 20

there are four molecules of CH4 are combined with molecules of O2
1CH4 + 2 O2 -) 1CO2 + 2H20
Draw before and after particle diagrams what is limiting what is excess
ON PACKET

Answer 20

make sure group based on first part then draw off grouping