Exam 2 Study Guide

Question 1

Molar Mass

Answer 1

The molar mass (MM) of a substance is the mass, in grams, of exactly one mole of that substance

Question 2

Conversion factor for mole A or grams A

Answer 2

molar mass g/mol

Question 3

Convert from grams of A to moles of A

Answer 3

divide grams by molar mass

Question 4

Convert from moles of A to grams of A

Answer 4

multiply moles by molar mass

Question 5

What information do chemical equations provide about the chemical reaction?

Answer 5

Identity of reactants and products in the form of chemical formulas.
Relative quantities of reactants and products consumed and produced respectively.
Physical states of reactants and products. Gas (g), liquid (l), solid (s), and aqueous (aq)

Question 6

Procedure for balancing equations

Answer 6

Write unbalanced equation with the identities of reactants and products.
Balance atoms in more complex molecules FIRST by adjusting coefficients.
Balance atoms that occur as free elements LAST by adjusting coefficients.
Adjust until coefficients are whole numbers.
You can only change coefficients: that is the number IN FRONT OF the compound. You may not change the chemical makeup of the compound
Check that total numbers of each type of atom are the same on each side.

Question 7

percent yield calculation

Answer 7

% 𝑦𝑖𝑒𝑙𝑑= (𝑎𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑)/(𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑) 𝑥 100%

Question 8

limiting reactant

Answer 8

the reactant that is entirely consumed in the reaction and limits the amount of product formed

Question 9

excess reactant

Answer 9

a reagent present in quantities greater than necessary to react with the quantity of limiting reactant

Question 10

Limiting reagent

Answer 10

the reactant that runs out first, and thus limits the amount of product that can be made (due to the law of constant composition).

Question 11

decomposition reaction

Answer 11

Question 12

combination/synthesis reaction

Answer 12

Question 13

single displacement reaction

Answer 13

Question 14

double displacement reaction

Answer 14

Question 15

combustion reaction

Answer 15

Question 16

solvation

Answer 16

Ionic compounds usually dissociate (separate) when put into water. This process is called solvation.

Question 17

Aqueous Solution

Answer 17

a solution in which the solvent is water.

Question 18

Solute

Answer 18

is the component that usually changes state.

Question 19

Solvent

Answer 19

is the component that keeps its state and is usually in excess.

Question 20

electrolyte solution

Answer 20

Salts (ionic compound) ionize when dissolved in water to form ions.

Question 21

nonelectrolyte solution

Answer 21

Molecular compounds do not dissociate when they dissolve; they DO NOT form ions.

Question 22

What factors predict the reactivity of ions in aqueous solution?

Answer 22

Two ions can form a solid (a precipitate) that is insoluble in water
BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2 NaCl(aq)

Two ions form a gas that escapes from the reaction mixture
HCO3- (aq) + H3O+(aq) → CO2(g) + 2H2O(l)

An acid neutralizes a base to form water (Chapter 8)
One ion can oxidize another (Chapter 8)

Question 23

Precipitation Reaction

Answer 23

Solution 1: NaCl(s) = Na+(aq) + Cl-(aq)

Solution 2: AgNO3(s) = Ag+(aq) + NO3-(aq)

Upon mixing NaCl + AgNO3 a precipitate forms.
Precipitates are insoluble and stay together as solids.

Question 24

What happens in a double displacement reaction?

Answer 24

There is an “exchange of ions” or a “switching of partners” between reactants to form products.

Question 25

Net ionic equation

Answer 25

shows only the ions that react (no spectator ions)

Question 26

spectator ions

Answer 26

ions that do not participate in a reaction

Question 27

Solubility Rules

Answer 27

Question 28

steps for solving for a reactant using a chemical equation

Answer 28

1. balance equation and identify compounds for mole ratio 2. use molar mass to convert g of starting compound to mol 3. use mole ratio from equations to calculate mols of desired compound 4. convert mols of desired compound to g using molar mass