Chapter 3

Question 1

stoichiometry

Answer 1

quantities of substances consumed and produced in chem reaction

Question 2

combination reaction

Answer 2

2+ substances combine to form 1 product

Question 3

decomposition reaction

Answer 3

1+ substance decomposes to form 2+ other substances

Question 4

combustion reaction

Answer 4

rapid reactions produce flame (with O2- air)

Question 5

combustion: meth-

Answer 5

1 carbon atom

Question 6

combustion: eth-

Answer 6

2 carbon atoms

Question 7

combustion: prop-

Answer 7

3 carbon atoms

Question 8

hydrocarbon formula:

Answer 8

C(n)H(2n+2)
(n = # of carbons)

Question 9

amu

Answer 9

mass of 1 proton

Question 10

atomic weight

Answer 10

avg amu of all isotopes; given on pt

Question 11

formula weight

Answer 11

sum of atomic weights in chem formula

Question 12

molecular weights

Answer 12

sum of atomic weights in a molecule

Question 13

mole

Answer 13

6.022 x 10^23 atoms

Question 14

molar mass

Answer 14

(g/mol)

Question 15

molar mass

Answer 15

mass of 1 mole of substance
- g/mol = formula weight

Question 16

empirical formula

Answer 16

lowest ration # of atoms

Question 17

combustion analysis

Answer 17

compound w/ C, H, O analyzed through combustion

Question 18

limiting reactant

Answer 18

completely consumed in reaction

Question 19

theoretical yield

Answer 19

quantity of product when limiting reactant in consumed

Question 20

actual yield

Answer 20

amount of product obtained (always less than theoretical yield)

Question 21

combustion formula

Answer 21

hydrocarbon + O2 (g) –> CO2 (g) + H2O (g)
(hydrocarbon = C(n)H(2n+2))

Question 22

percent mass composition

Answer 22

((number of atoms of element) x (atomic weight of element)) / (formula weight of substance) x 100%

Question 23

of molecules per 1 mol

Answer 23

1.66054 x 10^-24 molecules

Question 24

determining empirical formulas

Answer 24

1. Change % to grams
2. Calculate moles of each element
3. Divide by the smallest number of moles to calculate the mole ratio

Question 25

determining molecular formulas

Answer 25

1. Calculate molecular weight of empirical formula
2. Divide by experimental molecular weight
3. Multiply subscripts by this whole-number ratio

Question 26

Stoichiometric Calculations (ex: how many – to react away –)

Answer 26

1. grams of substance A–>
   (molar mass/(g/mol)) –>
2. moles of substance A –> –> moles of substance B
   (coefficient ratio from balance =) 3. (molar mass of B)
3. find: grams/milligrams

Question 27

steps for limiting reactant questions

Answer 27

1. write/balance equation
2. substance (A) g–>mol
3. mol-to-mol ratio
4. substance (B) mol–>g
   - if # is more than given amount = limiting
   - if # is less than amount; not limiting

Question 28

steps for theoretical yield

Answer 28

1. start w/ limiting reactant
2. g –> mol
3. mol-to-mol w/ (whole compound-to-limiting)
4. mol –> g (compound)