Thermochemistry

Question 1

thermochemistry

Answer 1

study of the change of energy that takes place when a reaction return

Question 2

endothermic reactions

Answer 2

decrease in temperature, heat reaction is positive

Question 3

intrinsic energy

Answer 3

potential energy, bonds energy

Question 4

activation energy

Answer 4

the minimum energy required for a reaction to take place

Question 5

enthalpy

Answer 5

capacity to release heat

Question 6

entropy

Answer 6

measure of disorder in a system

Question 7

exothermic reactions

Answer 7

give off energy and are associated with an increase in temperature

Question 8

translational

Answer 8

movement of molecules in their (liquids and gasses)

Question 9

rotational

Answer 9

rolling and flipping of molecules (liquids and gasses)

Question 10

collision molecular theory

Answer 10

no collision, no reaction

Question 11

vibratoinal

Answer 11

back and forth movement of molecules with respect to each other (solids, liquids and gasses)

Question 12

potential energy

Answer 12

stored in chemical bonds

Question 13

law of conservation of energy

Answer 13

energy is neither created nor destroyed under normal physical conditions, as molecular potential energy increases, kinetic energy decreases and visa-versa

Question 14

calorie (cal)

Answer 14

the amount of energy required to raise the temperature of one gram of water by one degree Celsius

Question 15

Kilocalorie (Kcal)

Answer 15

1 Kcal = 1000. calories

Question 16

Kilowatt hour (Kwh)

Answer 16

1 Kwh = 860 Kcal

Question 17

Joule (J)

Answer 17

1 cal = 4.184 J, 1 Kcal = 4.184 J

Question 18

heat energies in endothermic reactions

Answer 18

require heat; vaporization, fusion (melting), decomposition

Question 19

heat energies in exothermic reactions

Answer 19

release heat; condensation, solidification (freezing), synthesis, combustion

Question 20

enthalpy (△H)

Answer 20

represents the change in heat for any reaction: △Hrxn = ∑Hproducts - ∑Hreactants

Question 21

Hess’s Law

Answer 21

if you can combine the half reactions, you can combine the enthalpies

Question 22

specific heat (Cp)

Answer 22

energy required to raise the temperature of one gram of any substance by one degree celsius

Question 23

specific heat of H20(s)

Answer 23

0.500 cal/g℃

Question 24

specific heat of H20(l)

Answer 24

1.00 cal/g℃

Question 25

specific heat of H20(g)

Answer 25

0.500 cal/g℃

Question 26

heat of fusion (△Hfus)

Answer 26

energy required to melt one gram of any substance

Question 27

heat of fusion for water

Answer 27

80.0 cal/g

Question 28

heat of vaporization (△Hvap)

Answer 28

energy required ot vaporize one gram of any substance

Question 29

heat of vaporization for water

Answer 29

540.0 cal/g

Question 30

equations for calorimetry

Answer 30

``` Q = m x △T x Cp Q = m x △Hfus Q = m x △Hvap ```

Question 31

entropy (△S)

Answer 31

the change in disorder, chaos, or randomness for a substance or reaction △S>0, increase in disorder △S<0, decrease in disorder △S = ∑△Sproducts - ∑△Sreactants

Question 32

gibbs free energy (△G)

Answer 32

the chemical potential of a substance, predicts reaction spontaneity △G>0, reaction is non-spontaneous △G<0, the reaction is spontaneous △G = △H - T△S