Chapter 3.1 The Mole

Question 1

Stoichiometry

Answer 1

the study of the quantitative aspect of formulas and reactions

Question 2

Mole

Answer 2

SI unit for amount of substance
*the amount of a substance that contains the same number of entities as the number of entities as the number of atoms in 12g of carbon-12

Question 3

Avogadro’s Number

Answer 3

1 mole contains 6.022x10^23 entities (to four sig figs)

Question 4

Mole relating to Elements

Answer 4

mass in atomic mass units (amu) of one given atom of an element is the same numerically as the mass in grams of 1 mole of atoms of the element

Question 5

Example of Mole relating to Elements

Answer 5

ex. 1 atom of element S has a mass of 32.07 amu, and 1 mole (6.022x10^23 atoms) of element S has a mass of 32.07grams

Question 6

Mole Relating to Compounds

Answer 6

the mass in atomic mass units (amu) of one molecule (formula unit) of a compound is the same numerically as the mass in grams (g) of 1 mole of the compound

Question 7

Example of Mole relating to Compounds

Answer 7

1 Molecule of H2O has a mass of 18.02 amu, and 1 mole (6.022x10^23 molecules) of H2O has a mass of 18.02g

Question 8

Molar Mass (MM)

Answer 8

Mass per mole of its entities (atoms, ions, molecules, formula units) and has units of grams per mole (g/mol)

Question 9

What is needed to calculate Molar Mass?

Answer 9

The periodic table

Question 10

How to find the Molar mass of an element

Answer 10

look up atomic mass and find out if it is monatomic or molecular

Question 11

Molar Mass of Monatomic Element…?

Answer 11

is equal to the Periodic table value in grams per mole

Question 12

Molar Mass of Molecular Element…?

Answer 12

know how many molecules the element likes to be in

Question 13

Example of Molar Mass of Molecule Element (In air, oxygen exists as O2, so the Molar Mass of oxygen is…?

Answer 13

Molar Mass O2 = 2 x Molar Mass of O = 2 x 16.00 g/mol = 32.00 g/mol

Question 14

How to find the Molar Mass of a Compound

Answer 14

the molar mass is the sum of the molar masses of the atoms in the formula

Question 15

Example of Molar Mass of a Compound (what is the Molar Mass of SO2?)

Answer 15

Molar Mass SO2 = Molar Mass of S + (2 x Molar Mass of O) = 32.07g/mol + (2 x 16.00g/mol) = 64.07g/mol

Question 16

Converting between AMOUNT and MASS: (Moles to Grams)

Answer 16

*Multiply by the Molar Mass:

Mass (g) = (amount (in moles) x (number of grams/1 mole))

Question 17

Converting between AMOUNT and MASS: (Grams to Moles)

Answer 17

*Divide by the Molar Mass:

Amount (moles) = (Mass (in grams) x (1 mole/number of grams))

Question 18

Converting between AMOUNT and NUMBER: (Moles to Entities)

Answer 18

*Multiple by Avogadro’s Number:

Number of entities = amount (moles) x [(6.022x10^23 entities)/(1 mole)]

Question 19

Converting between AMOUNT and NUMBER: (Entities to Moles)

Answer 19

*Divide by Avogadro’s Number

Amount (moles) = number of entities x [(1 mole)/(6.022x10^23)]

Question 20

Going from Moles of Compound to Moles of Element

Answer 20

Use Chemical Formula:

*Subscripts = Moles of element in compound

Question 21

Mass Percent Equation of any Element in a COMPOUND

Answer 21

Mass % of any Element in a Compound =

([(atoms of Element S in formula) x (atomic mass of X)] / (Molecular mass of compound in amu)) x 100

Question 22

Mass Percent Equation of each Element on a mole basis

Answer 22

Mass % of Element =
([(moles of X in formula) x (molar mass of X in g/mol)] /
(mass in g of 1 mole of compound))

Question 23

Equation to find the Mass of an Element from its Mass percent

Answer 23

Mass of Element = mass of compound x (mass of element in 1 mole of compound/ Mass of 1 mole of compound)