Chapter 4- Compounds And Stoichiometry

Question 1

Molecular Mass vs Molecular Weight

Answer 1

Molecular weight is the mass of the constituent atoms in a compound as indicated by the molecular formula.

Molar mass is the mass of one mole (6.022×10 to the 23 particles) of a compound. Usually measured in grams per mole.

Question 2

Gram equivalent weight

Answer 2

The measure of the mass of a substance that can donate one equivalent of the species of interest.

Question 3

Normality

Answer 3

The ratio of equivalence per liter. Related to molarity by multiplying molarity by the number of equivalence present per mole of compound.

Normality = equivalents/L

Question 4

Molarity

Answer 4

Morlarity = Normality/n

Question 5

Equivalents

Answer 5

Moles of the species of interest.

Equivalents are most often seen in acid/base chemistry and oxidation reduction reactions.

Question 6

Law of constant composition

Answer 6

Any pure sample of a compound will contain the same elements in the same mass ratio.

For example a sample of water will contain two hydrogen atoms per one oxygen atom, in terms of mass for everyone gram of hydrogen, there will be 8g of oxygen.

Question 7

Empirical vs Molecular formula

Answer 7

Empirical formula is the smallest WHOLE NUMBER RATIO of the elements in a compound.

Molecular formula is either the same or a multiple of the empirical formula gives EXACT NUMBER of atoms of each element in a compound.

Question 8

How to calculate percent composition

Answer 8

Determine the mass of the individual element and divide by the molar mass of the compound.

Mass of individual element/Molar mass of compound

Question 9

Combination vs Decomposition

Answer 9

Combination reaction two or more reactants combine to form one product.

Decomposition reactions when reactive chemically broken down into two or more products.

Question 10

Combustion reaction

Answer 10

When an oxidant (typically oxygen) reacts forming the products water and carbon dioxide

Question 11

Displacement reaction

Answer 11

When one or more atoms or ions of one compound are replaced with one or more atoms or ions of another compound.

Include single displacement- occurs when one ion of a compound is replaced with another element

double displacement-Occurs when elements from two different compounds trade places with each other to form two new compounds

Question 12

Neutralization reactions

Answer 12

Where an acid reacts with a base to form a salt usually water

Question 13

Three rules for balancing equations

Answer 13

1. Balancing the least common atoms
2. Balancing the more common atoms (usually hydrogen and oxygen)
3. Balancing charge if necessary

Question 14

Limiting reagent

Answer 14

The reactant that will be consumed first in a chemical reaction.

Can be determined by using the balanced equation.

Question 15

Theoretical vs actual vs percent yield

Answer 15

Theoretical yield is the amount of product generated if all the limiting reactants are consumed with no side reactions.

Actual yield is typically lower than theoretical yield.

Percent yield is calculated by dividing actual yield by theoretical yield and converting to a percentage.

(Actual yield/Theoretical yield) x100

Question 16

How is ionic charge denoted four elements?

Answer 16

With Roman numerals

Question 17

-ous ending ions

Answer 17

Used to indicate lesser charge

Question 18

-ic ending ions

Answer 18

indicates greater charge

Question 19

Monatomic anions end in what suffix?

Answer 19

-ide

Question 20

Oxyanions with a lesser amount of oxygen has what suffix/prefix?

Answer 20

-ite

hypo-

Question 21

Oxyanions with a greater amount of oxygen have a suffix/prefix?

Answer 21

-ate

per-

Question 22

Polyatomic ions containing one or two hydrogens are given what label?

Answer 22

1: Hydrogen/bi
2: Dihydrogen

Question 23

Metals and nonmetals Form positive or negative ions? Nonmetals form positive or negative ions?

Answer 23

Metals form positive cations. Nonmetals form negative anions.

Question 24

Electrolytes

Answer 24

Contain equivalents of ions or molecules a dissociating solution. The strength of an electrolyte depends on its degree of dissociation or solvation.

Question 25

Units for molar mass

Answer 25

g/mol

Question 26

Equation for gram equivalent weight

Answer 26

Molar mass / n

Question 27

Equation to calculate normality

Answer 27

molarity x n

Question 28

Equation to calculate the percent composition

Answer 28

Mass of the element in the formula/molar mass of the compound x 100%