13 Test

Question 1

the branch of science that studies the transfer of energy during chemical reactions or phase changes, is an important application of these laws

Answer 1

thermochemistry

Question 2

expresses the average kinetic energy in the particles of a sample. It is measured in degrees Celsius or in Kelvins

Answer 2

temperature

Question 3

insulated container, similar to a thermos, in which a thermometer detects the temperature (also known as enthalpy) change that occurs during a chemical reaction

Answer 3

calorimeter

Question 4

what is heat that produces a phase change

Answer 4

latent heat

Question 5

what is heat that produces a temperature change in the substance when applied

Answer 5

sensible heat

Question 6

why do enthalpies of vaporization differ widely

Answer 6

because the strength of intermolecular attractions in different liquids varies

Question 7

what of a substance is the amount of thermal energy required to raise the temperature of 1g of the substance by 1 C

Answer 7

specific heat (Csp)

Question 8

substances with WHAT specific heats require large amounts of energy for a given temperature change and will change temperature only slowly

Answer 8

high

Question 9

which retains heat longer, substances with high specific heat values or low specific heat values

Answer 9

high specific heat values

Question 10

why do the products in an exothermic reaction have a lower enthalpy than the reactants

Answer 10

because energy is released during the reaction

Question 11

a negative enthalpy of reaction value signifies what kind of reaction

Answer 11

exothermic

Question 12

the enthalpy of a reaction of a reverse reaction has the —– magnitude but ———- sign of the delta H of the foward reaction

Answer 12

same, opposite

Question 13

what is enthalpy change for the reaction that produces 1 mol of a compound in its standard state from its elements in their standard states

Answer 13

standard molar enthalpy of formation (delta Hf)

Question 14

what does the degree symbol in delta Hf mean

Answer 14

signifies that this delta H refers to standard conditions

Question 15

what is standard molar enthalpy of combustion (delta Hc)

Answer 15

the energy released as heat by the complete burning of one mole of a substance at standard conditions

Question 16

what does Hess’s law state

Answer 16

the enthalpy change of a reaction equals the sum of the enthalpy changes for each step of the process

Question 17

what is always required to break bonds

Answer 17

energy

Question 18

entropy ——– as temperature increases

Answer 18

increases

Question 19

what is the formula for calculating free-energy change (delta G)

Answer 19

delta G= delta H-Tdelta S
T is the temperature in kelvins
delta G is the difference between the free energy of the products and the free energy of the reactants

Question 20

what does a negative delta G indicate

Answer 20

decline in free energy and signifies that a reaction may occur spontaneously (or is favorable)

Question 21

the quantity of thermal energy required to convert one mole of a liquid at its boiling point to its vapor at the same temperature; also called the heat of vaporization. it is usually expressed in units of kilojoules per mole. higher values means stronger intermolecular attractions is what?

Answer 21

completely define molar enthalpy of vaporization (delta Hvap)

Question 22

what is a chemical equation that shows the reactants, products, and amount of energy that is released or absorbed as heat

Answer 22

define thermochemical equation

Question 23

in thermodynamics, 25 C (298 K) and 1 atm of pressure is called what?

Answer 23

standard state

Question 24

the measure of the dispersal of energy in a system; the net decreases of usable energy in a system for a given temperature and quantity of matter. entropy measures randomness of a system is what?

Answer 24

entropy (S)

Question 25

when determining free energy change temperature must be in what?

Answer 25

kelvin

Question 26

which has more entropy gas, liquids, or solids

Answer 26

gas

Question 27

in spontaneous natural processes entropy tends to what?

Answer 27

entropy increases and enthalpy decreases

Question 28

what is average kinetic energy sample substance

Answer 28

temperature