unit 2

Question 1

what is a chemical reaction?

Answer 1

a chemical reaction is the conversion of one or more substances into another substance.

Question 2

what is stoichiometry?

Answer 2

the process of determining the amounts of substances in a chemical reaction.

Question 3

limiting reactants?

Answer 3

whichever elements limits the reaction.

Question 4

excess reaction?

Answer 4

the reactant which is left over after the reaction.

Question 5

theoretical yield?

Answer 5

the mass of product that you calculate. the maximum amount of material that you can “theoretically” make from the reactants provided.

Question 6

actual yield?

Answer 6

the mass of product that is recovered under experimental conditions.

Question 7

percentage yield formula?

Answer 7

% = actual / theoretical x 100

Question 8

solubility?

Answer 8

the maximum amount of solute that will dissolve in a given quantity of solvent at a specific temperature.

Question 9

precipitate?

Answer 9

insoluble solid that separates from the solution.

Question 10

precipitation reaction?

Answer 10

a precipitation reaction refers to the formation of an insoluble salt when two solutions containing soluble salts are combined.

Question 11

what are ionic equations?

Answer 11

the dissolved species as free ions. only soluble compounds are split into ions.

Question 12

acid-base reactions?

Answer 12

acid and base combines to produce a salt.

Question 13

redox reactions?

Answer 13

oxidation and reduction half reactions.

Question 14

oxidation?

Answer 14

loss of electrons, also the reducing agent. donates electrons to the reactant being reduced.

Question 15

reduction?

Answer 15

gain of electrons. the reactant being reduced is the oxidising agent. accepts electrons from the reactant being oxidised.

Question 16

oxidation number rules?

Answer 16

lone elements have ON of 0, ON is equal to charge on the ion, ON of oxygen is usually -2, hydrogen is +1, group 1 metals are +1, group 2 metals are +2 and Fl is -1.

Question 17

types of redox reactions?

Answer 17

combination - A+B–>C
decomposition - C –> A+B
combustion - A + O2 –> B

Question 18

titration?

Answer 18

a solution of known concentration is gradually added to a solution of unknown concentration until the reaction between the two solutions is complete.

Question 19

standard solution?

Answer 19

a solution of accurately known concentration.

Question 20

energy?

Answer 20

the capacity to do work.

Question 21

radiant energy?

Answer 21

energy which comes from the sun and earth’s primary energy source.

Question 22

thermal energy?

Answer 22

is the energy associated with the random motion of atoms and molecules.

Question 23

heat?

Answer 23

the transfer of thermal energy between two bodies that are at different temperatures.

Question 24

chemical energy?

Answer 24

the energy stored within the bonds of chemical substances.

Question 25

temperature?

Answer 25

a measure of thermal energy.

Question 26

nuclear energy?

Answer 26

is the energy stored within the collection of neutrons and protons in the atom.

Question 27

potential energy?

Answer 27

is the energy available by virtue of an object’s position.

Question 28

thermochemistry?

Answer 28

the study of heat change in chemical reactions.

Question 29

the system?

Answer 29

the system is the specific part of the universe that is of interest in the study.

Question 30

exothermic reactions?

Answer 30

heat is released and given off by the system to the surroundings.

Question 31

endothermic reaction?

Answer 31

heat is absorbed by the system from the surroundings.

Question 32

specific heat?

Answer 32

the specific heat of a substance is the amount of heat required to raise the temperature of one gram of the substance by one degree celsius.

Question 33

heat capacity?

Answer 33

the heat capacity of a substance is the amount of heat required to raise the temperature of a given quantity of the substance by one degree celsius.

Question 34

thermodynamics?

Answer 34

the scientific study of the interconversion of heat and other types of energy.

Question 35

first law of thermodynamics?

Answer 35

energy can be converted from one form to another but cannot be created nor destroyed.

Question 36

first law equation?

Answer 36

changeE = q + w
w = -P(delta)V

Question 37

sign conventions for work and heat?

Answer 37

work done by the system on the surroundings (-), word done on the system by the surroundings (+), heat absorbed by the system from the surroundings (+), heat absorbed by the surroundings from the system (-).

Question 38

enthalpy?

Answer 38

used to quantify the heat flow into or out of a system in a process that occurs at a constant pressure.

Question 39

standard enthalpy of formation?

Answer 39

the heat change that results when one mole of a compound is formed from its elements at a pressure of 1 atm.

Question 40

standard enthalpy of reaction?

Answer 40

is the enthalpy of reaction carried out at 1 atm.

Question 41

hess’s law?

Answer 41

when reactants are converted to products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps. Enthalpy is a state function. it doesn’t matter how you get there, only where you start and end.

Question 42

the enthalpy of solution?

Answer 42

the enthalpy of solution is the heat generated or absorbed when a certain amount of solute dissolves in a certain amount of solvent.