Chapter 3

Question 1

Avogadro’s number

Answer 1

Number of particles

6.022*10^23

Question 2

Molar mass

Answer 2

The mass in grams of one mole of a substance

Question 3

Formula weight

Answer 3

The sum of the atomic weights if the elements that make up a substance

Question 4

Molecular weight

Answer 4

Substances that exist as individual molecules

Question 5

Stoichiometry

Answer 5

The study of the relationship between relative amounts of substances

Question 6

Percent composition

Answer 6

The mole-to-mole relationship in a chemical formula used to determine this of an element in a compound

Question 7

Molecular formula

Answer 7

The whole number multiple of its empirical formula (for a compound)

Question 8

Hydrated ionic compound

Answer 8

An ionic compound that has a well defined amount of water trapped within the crystalline solid

Question 9

Hydrated formula solving for compound

Answer 9

10.0g CuSO4*5H2O 
x 1molCuSO4*5H2O/249.68g(molar mass)
x 5molH2O/1molCuSO4*5H2O
x 18.015g/1molH2O
= 3.61g H2O
10.0g CuSO4*5H2O - 3.61g H2O
= 6.39g CuSO4

Question 10

Hydrated formula solving for H2O

Answer 10

BeSO4*xH2O --heat--> BeSO4 + xH2O
43.80g (original)              25.98g (after heat)
x = mol H2O/mol BeSO4
25.98g x 1mol BeSO4/105.07g (molar mass)
= .2473mol BeSO4
mass H2O = 43.80g - 25.98g = 17.82g
17.28g H2O x 1mol H2O/18.015g = .9891mol H2O
x = .9891mol H2O/.2473 BeSO4
x = 4

Question 11

Mole

Answer 11

Unit used when counting numbers of atoms or molecules in a sample (mol)