GChem: Metric Units, moles, oxidation states

Question 1

SI of joules

Answer 1

kgm^2/s^2

Question 2

Mega

Kilo

Answer 2

10^6

10^3

Question 3

1000L = ___m^3

Answer 3

1m^3

Question 4

1L=____cm^3

Answer 4

1000cm^3

Question 5

SI unit of volume

Answer 5

cubic meter m^3

Question 6

Moles

Answer 6

moles of solute per liter of solution

Question 7

1mL = …. =….

Answer 7

1mL = 1 cm^3 = 1cc

Question 8

Angstrom Å = __m

Answer 8

Angstrom Å = 10^10 m

Question 9

Density ρ = _____
In SI units density is ____
but in chem, densities are most often presented in units
_____. This unit of density is convenient cause most liquids and solids have a density of 1 to 20 ____.

Answer 9

Density ρ = mass/volume = m/V
SI = kg/m^3
g/cm^3

To convert:
g/cm^3 -> multiply by 1000 -> kg/m^3
g/cm^3

Question 10

Density of water

Answer 10

1 g/cm^3
By using logic of other flashcard, what would density be in kg/m^3?

1000kg/m^3

Question 11

Avogadro’s number/a mole

Answer 11

6.02 * 10^23

Question 12

The number listed on periodic table given tells you:
a)
b)

Answer 12

a) atomic mass units (amu) to calculate molecular weight

b) grams of element in 1 mole of the element

Question 13

moles = ____/_____

Answer 13

moles = mass in grams/molecular weight (MW)

Question 14

Percent mass composition/percent composition

Answer 14

molecular weight of that element in molecule/empirical molecular weight

Question 15

a) We can use info about percentage composition to determine a compound’s empirical formula. Describe process
b) What is empirical formula of a compound that is 90 percent carbon and 10 percent hydrogen?

Answer 15

a) Suppose a substance is found to have, by mass, 70% iron and 30% oxygen. To find the empirical formula for this compound, the trick is to start with 100 grams of the substance so that the substance would have 70g iron and 30g oxygen. Now, how many moles of Fe and O are present in this 100g substance? We can use formula # moles = mass in grams/molecular weight (MW) and fact that MW Fe = 55.8 and MW O = 16 and plug in to get moles of each. Then set the moles of Fe over moles of O to find ratio of moles and then can use ratio to write empirical formula. in this case ratio of Fe to O is 2:3 so Fe2O3
b) C3H4 page 40

Question 16

Molarity = _____/_____

Answer 16

Molarity = # moles of solute/ #liters of solution

Question 17

Mole fraction (S)

Answer 17

Expresses the fraction of moles of a given substance relative to the total moles in solution 
mole fraction (S) = # moles of substance S/ total # moles in solution

Question 18

The stoichiometric coefficients mean:
a)
b)

Answer 18

a) # molecules
b) # of moles

The stoichiometric coefficients provide ratios of molecules or moles, not ratios by mass

Question 19

How many grams of HCl are required to produce 534 grams of aluminum chloride? (Page 44)

Answer 19

438g

Question 20

Find the limiting reagent of 2ZnS + 3O2 -> 2ZnO + 2SO2
if 97.5 g of ZnS undergoes reaction with 32 g O2.

If want faster solve: there is 1 mole ZnS and 1 mole O2

Answer 20

O2 (page 45)
First calculate the moles of each REAGENT then look at the coefficients
Then divide moles of each reagent/coefficient in balanced chemical reaction

Question 21

Oxidation state rules - Page 47

1. Oxidation state for any element in its standard state
2. Oxidation state for atoms in neutral molecules and ions
3. Group 1 metals, Group 2 metals:
4. Fluorine:
5. Rule about hydrogen
6. Rule about oxygen
7. Halogens and atoms of the oxygen family

Answer 21

0
add to 0 or the charge if an ion
Group 1 metals: +1 oxidation state
Group 2 metals: +2 oxidation state
Fluorine: -1
Hydrogen has a +1 oxidation state when bonded to
something more electronegative than C, - 1 when bonded to something less electronegative, and 0 when bonded to carbon
Oxygen has a -2 oxidation state except when in peroxides (H2O2, Na2O2) then it has an oxidation state of -1 which is consistent with rules 3 and 5
Rest of the halogens have a -1 oxidation state, and the atoms of the oxygen family have a -2 oxidation state

Question 22

Electronegativities mnemonic
How does it relate to H oxidation states?
Side note: The oxidation number of a transition metal is given as a Roman numeral in the name of the compound:
FeCl2 is iron(II) chloride

Answer 22

FONClBrISCH (list most EN to least EN) Hence bonds from H to anything before C will give H +1 oxidation state and bonds from H to anything NOT found in list will give H a -1 oxidation state

Question 23

Mass number

can be written as subscript or superscript?

Answer 23

Number of protons plus neutrons

Superscript or with a hyphen after atom (ex. Beryllium-9)

Question 24

Atomic number
can be written as subscript or superscript?
another word for atomic number is…

Answer 24

Number of protons
Subscript

Nuclear charge

Question 25

Atomic weight

Answer 25

Weighted average of the masses of atoms naturally occuring isotypes and this is the value listed in the periodic table
ex. for boron there are two isotypes
(20%)(10.013 amu) + (80%)(11.009 amu)

Question 26

Mass of neutron and proton
Mass of electron
(assumptions for easy calc)

Answer 26

1 amu

0 amu