Chapter 7 Flashcards

1
Q

What two things play an important role in determining the extent and speed of a chemical reaction?

A

1) Thermodynamics, which deals with energy changes in chemical reactions
2) Kinetics, which describes the rate or speed of a chemical reaction

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2
Q

Thermodynamics

A

study of energy, work, and heat

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3
Q

3 Basic laws of thermodynamics?

A

1) energy cannot be created or destroyed, only converted from one form to another
2) the universe spontaneously tends toward increasing disorder or randomness
3) the disorder of a pure, perfect crystal at absolute zero is zero 0 (Kelvin)

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4
Q

Average kinetic energy of atoms or molecules does what with increasing temperature?

A

Increases

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5
Q

What happens when some collisions of molecules occur with sufficient energy?

A

can break bonds in molecules

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6
Q

What can happen when a reactant bond is broken?

A

new bonds may be formed and products result

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7
Q

System?

A

contains the process under study

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8
Q

Surroundings?

A

encompass the rest of the universe (system)

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9
Q

Heat

A

transfer of thermal energy to the surroundings; sometimes consider heat flow

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10
Q

Calorimetry

A

Experimental strategies for measuring temperature change and calculating heats of reactions

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11
Q

Exothermic reaction

A

Releases energy to the surroundings (surroundings become warmer)
representative with a negative sign

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12
Q

Endothermic reaction

A

absorbs energy from the surrounds (surrounding become colder)
representative with a positive sign

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13
Q

Enthalpy

A

term used to represent heat and is symbolized as H

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14
Q

If H reactants > H products, what is H?

A

H must be negative and the reaction is exothermic

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15
Q

If H reactants < H products, what is H?

A

H must be positive and the reaction is endothermic

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16
Q

Entropy

A

A measure of the randomness of a chemical system.

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17
Q

Symbol for entropy?

A

symbol S

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18
Q

Free Energy

A

symbol G, represents the combined contribution of the enthalpy and entropy values for a chemical reaction

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19
Q

4 situations of G

A
  • H (neg) & S (pos), G is always pos, regardless of temp
  • H (pos) & S (neg), G is always neg, regardless of temp
  • H (pos) & S (neg), G depends on temp
  • H (neg) & S (neg), G depends on temp
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20
Q

specific heat

A

number of calories (cal) of heat needed to raise the temperature of 1 gram (g) of the substance 1 degree Celsius (c).

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21
Q

Quantity of heat absorbed or released by the reaction (Q)?

A

mass of solution in the calorimeter (Ms), (X)
specific heat of the solution (SHs), (X)
change in temperature (Ts) of the solution

22
Q

Fuel Value

A

is the amount of energy per g of food

23
Q

Nutritional Calories (Cal)

A

equivalent to one kilo-calorie (1000 cal), known as the large Calorie

24
Q

bomb caloriemeter

A

measurement of the fuel value (Cal) of foods

25
Q

Effective collision

A

producing product molecules (requires sufficient energy and, in the case of complex molecules, the proper orientation of reaction molecules.

26
Q

Activation energy

A

Ea, minimum amount of energy required to initiate a chemical reaction

27
Q

Activated complex

A

reaction proceeds from reactants to products through an extremely unstable state

28
Q

Factors that affect reaction rate

A

1) structure of the reacting species
2) molecular shape and orientation
3) the concentration of reactants
4) the temperature of reactants
5) the physical state of reactants
6) the presence of a catalyst

29
Q

Catalyst

A

substance that increases the reaction rate

30
Q

K

A

rate constant @ specific temp

31
Q

rate laws

A

rate being equal to the rate constant multiplied by the reactant concentration raised to an exponent

32
Q

equilibrium reactions

A

reactions that do not go to completion. no further obvious change is taking place, measurable quantities of reactants and products remain

33
Q

reversible reaction

A

process that can occur in both directions

34
Q

dynamic equilibrium

A

situation in which the rate of the forward process in a reversible reaction is exactly balanced by the rate of the reverse process

35
Q

equilibrium constant

A

Keq = products/reactants

36
Q

Is Keq temp dependent or not?

A

temp dependent

37
Q

what temp is equilibrium constant reported at?

A

25 degree C

38
Q

Molarity?

A

(mol/L)

39
Q

LeChatelier’s principle

A

if a stress is placed on a system at equilibrium, the system will respond by altering the equilibrium composition in such a way to minimize the stress

40
Q

Add product, equilibrium shifts to the ?

A

Left

41
Q

Add reactant, equilibrium shifts to the ?

A

Right

42
Q

N2(g) + 3H2 (G) 2NH3 (g) + kcall is a what reaction?

A

exothermic

43
Q

How does equilibrium shift when heat is added to exothermic reaction?

A

will shift left

44
Q

How does equilibrium shift when heat is removed from an exothermic reaction?

A

will shift right

45
Q

How does equilibrium shift when heat is added to endothermic reaction?

A

will shift right

46
Q

How does equilibrium shift when heat is removed from an endothermic reaction?

A

will shift left

47
Q

39 kcal + 2N2(g) + O2(g) 2N2O(g) is what type of reaction?

A

endothermic reaction

48
Q

Pressure on an equilibrium reaction does what to reaction

A

shifts to the side that has the least amount of mole

49
Q

pressure released on an equilibrium reaction does what to the reaction

A

shifts to the side that has the most amount of moles

50
Q

Catalyst do what to an equilibrium reaction?

A

no change