Chapter 18-20

Question 1

Reaction assumptions

Answer 1

Reactions are spontaneous: nothing can predict whether given substances will react
Reactions are fast: for a reaction to be useful it must occur within a reasonable time
Reactions are quantitative: is more than 99% complete, at least one reactant is completely used up, a reaction goes until completion
Reactions are stoichiometric: there is a simple whole number ratio of chemical amounts (moles) of reactants and products

Question 2

Writing net ionic equations

Answer 2

Cancel identical entities that appear on both reactant and product sides, when cancelling spectator ions they must be identical in every way (# of miles, form, and state)

Question 3

Review of chemical reactions

Answer 3

Formation= element> compound
Decomposition=compound>
element
Single replacement: element+compound >element+compound
Double replacement: compound+compound >compound+compound
Combustion: substance+ oxygen> common oxides

Question 4

Mole ratio

Answer 4

Multiply the known amount of moles by the unknown molar coefficient and divide by the known molar coefficient
N* n unknown/ n known

Question 5

Percent yield

Answer 5

Evaluates the overall experiment, is the ratio of the actual or experimental quantity of product obtained to the theoretical yield obtained from stoichiometry calculation
Percent yield=actual yield/ predicted yield x100

Question 6

Common sources of experiment uncertainty

Answer 6

All measurements
Purity of the grade of chemical used
Washing precipitate(fine particles may be lost)
Qualitative measurements(estimations that affect measurements)

Question 7

Stoichiometry

Answer 7

The description of the relative quantities of the reactants and products by chemical amounts (moles)

Question 8

Gravimetric stoichiometry

Answer 8

The procedure for calculating the masses of reactants and products in a chemical reaction, chemical amount calculations are made from mass measurements

Question 9

Gas stoichiometry

Answer 9

Stoichiometry is extended to gases using gas volume, pressure, temperature, molar volume, and ideal gas law

Question 10

Solution stoichiometry

Answer 10

The application of stoichiometric calculation principles to solutions

Question 11

Chemical reactions do not explain

Answer 11

Pressure and temperature conditions
Progress and process of a reaction
Measurable quantities

Question 12

Quantitative reaction

Answer 12

One that is more than 99% complete

Question 13

Stoichiometric reaction

Answer 13

There is a simple whole number ratio of chemical amounts of reactants and products

Question 14

Net ionic equation

Answer 14

A chemical reaction equation that includes only reacting entities (molecules, atoms, ions) and omits any that do not change

Question 15

Spectator ion

Answer 15

An ion that is present but does not take part in a chemical reaction

Question 16

Limiting reagent

Answer 16

The reactant whose entities are completely consumed in a reaction, meaning reaction stops when all reactant is used up and none remains

Question 17

Excess reagent

Answer 17

Reactant whose entities are present in surplus amounts, so that some remains after the reaction ends