thermochemistry vocab

Question 1

Thermochemistry

Answer 1

The study of the transfers of energy as heat that
accompany chemical reactions and physical changes

Question 2

Calorimeter

Answer 2

Used to measure the energy absorbed or released as
heat in a chemical reaction or physical change

Question 3

Temperature

Answer 3

A measure of the average kinetic energy of the
particles in a sample of matter

Question 4

Heat

Answer 4

Energy transferred between samples of matter
because of difference of temperature

Question 5

Enthalpy of reaction

Answer 5

The quantity of energy transferred as heat during a
chemical reaction
∆H = H products – H reactants

Question 6

Enthalpy of formation

Answer 6

Enthalpy change that occurs when one mole of a
compound is formed at 25°C and 1 atm

Question 7

Hess’s Law

Answer 7

the overall enthalpy change in a reaction that is equal to the sum of the individual steps in the process.

Question 8

Entropy

Answer 8

The tendency of nature towards increasing
randomness in a system.

Question 9

Specific heat

Answer 9

the amount of energy required to raise
the temperature of one gram of a substance by one
Celsius/kelvin degree.

Question 10

Reaction mechanism

Answer 10

Step by step sequence of reactions by which the
overall chemical change occurs

Question 11

Reaction Rate

Answer 11

The change in concentration of reactants per unit
time as a reaction proceeds

Question 12

Nature of Reactants

Answer 12

Different substances react differently to other substances

Question 13

Surface Area

Answer 13

Increased surface area increases reaction rates

Question 14

Temperature

Answer 14

Increased temperature increases kinetic energy which
increases collisions which increase reaction rates

Question 15

Concentration

Answer 15

Increased concentration leads to increased collisions which increases reaction rates

Question 16

Catalysts

Answer 16

A substance that changes the rate of a chemical reaction without itself being permanently consumed.

Question 17

Rate Law

Answer 17

An equation that relates reaction rate and concentrations of reactants for the reaction

Question 18

Specific Rate Constant

Answer 18

The proportionality constant relating the rate of the reaction to the concentrations of reactants. (k)

Question 19

Reversible reaction

Answer 19

a chemical reaction in which the products can react to reform reactants

Question 20

Common-ion effect

Answer 20

the addition of an ion common to two solutes brings about precipitation or reduced ionization

Question 21

acid ionization constant

Answer 21

(ka) like the equilibrium constant, k, is constant for a specified temperature but has a new value for each new temperature

Question 22

hydrolysis

Answer 22

a reaction between water molecules and ions of a dissolved salt is hydrolysis

Question 23

Chemical equilibrium

Answer 23

when the rate of its forward reaction equals the rate of its reverse reaction and the concentrations of its products and reactants remain unchanged

Question 24

Equilibrium constant

Answer 24

(k) is the ratio of the mathematical product of the concentrations of reacting substances

Question 25

Chemical equilibrium expression

Answer 25

k= [HI]^2 ------------- [H2][I2]

Question 26

Buffered solution

Answer 26

a solution that can resist changes in pH

Question 27

Hydrolysis

Answer 27

a reaction between water molecules and ions of a dissolved salt

Question 28

Solubility product constant

Answer 28

the equilibrium constant for a solid substance dissolving in an aqueous solution.

Question 29

Le Chatelier’s principle

Answer 29

when a stress (a change in concentration, pressure, or temperature) is applied to a system at equilibrium, the equilibrium is shifted in the direction that relieves the stress.