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Chemistry 12 > Unit 1 > Flashcards

Unit 1 Flashcards

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1
Q

Consider the following factors: I. Concentration of reactants. II. Temperature of reactants. III. Surface area of reactants. The factors that affect the rate of a chemical reaction between two gases are Select one: a. I and II only. b. I and III only. c. II and III only. d. I, II and III.

A

A

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2
Q

The addition of a catalyst to a reaction provides an alternate mechanism with Select one: a. lower activation energy and lower reaction rate. b. lower activation energy and higher reaction rate. c. higher activation energy and lower reaction rate. d. higher activation energy and higher reaction rate.

A

B

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3
Q

Consider the following reactions I. N2 (g) + O2 (g) → 2 NO (g) II. 2 Mg (s ) + O2 (g) → 2 MgO (s ) III. CaCO3 (s) + 2 H+ (aq ) → Ca2+(aq ) + H2O (l) + CO2 (g) Increasing the surface area will increase the reaction rate in Select one: a. II only b. I and III only c. II and III only d. I, II and III

A

C, due to the solids

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4
Q

The activation energy of a reaction in solution Select one: a. increases with the addition of a catalyst b. decreases with a decrease in temperature. c. increases if the solution is stirred vigorously d. does not change with an increase in temperature

A

D

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5
Q

Consider the reaction: 2 Al (s) + 6 HCl (aq) → 2 AlCl3 (aq) + 3 H2 (g) A 0.040 mol piece of aluminum reacted completely in 20 s. The rate of formation of hydrogen gas is Select one: a. 0.0013 mol/s b. 0.0020 mol/s c. 0.0030 mol/s d. 0.0060 mol/s

A

C

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6
Q

Consider the following: 1/2 N2 (g) + 1/2 O2 (g) → NO (g) ΔH = + 90 kJ/mol NO The correct equation including the heat term is Select one: a. N2 (g) + O2 (g) + 90 kJ → 2 NO (g) b. N2 (g) + O2 (g) + 180 kJ → 2 NO (g) c. N2 (g) + O2 (g) → 2 NO (g) + 90 kJ d. N2 (g) + O2 (g) → 2 NO (g) + 180 kJ

A

B

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7
Q

Consider the following reaction: 2 NO2 (g) ⇌ 2 NO (g) + O2 (g) Under certain conditions, the rate of decomposition of NO2 is 3. 2 × 10 −3 mol / s. The rate of formation of O2is Select one: a. 1.6 × 10 −3 mol / s b. 3.2 × 10 −3 mol / s c. 4.8 × 10 −3 mol / s d. 6.4 × 10 −3 mol / s

A

A

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8
Q

Consider the following reaction mechanism: Step 1: NO2+ NO2 → NO + NO3 Step 2: NO3+ CO → NO2+ CO2 The overall reaction is…. Select one: a. NO2 + CO → NO + CO2 b. NO2 + NO3 + CO → NO3 + NO2 + NO + CO2 c. 2NO2 → NO3 + NO d. NO3 + CO → NO2 + CO2

A

A

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9
Q

Which of the following will decrease the number of effective collisions during a chemical reaction? Select one: a. Decreasing the temperature. b. Increasing the surface area. c. Increasing reactant concentrations. d. Adding a catalyst.

A

A –> Decreasing the temperature will cause the molecules in a reaction to decrease in speed. As a result, the number of collisions decrease as the energy required for an effective collision can not be reached as frequently.

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10
Q

A catalyst increases the rate of a chemical reaction by…. Select one: a. increasing kinetic energy. b. decreasing the heat of reaction. c. providing an alternate reaction mechanism. d. increasing the temperature e. increasing the concentration of reactants.

A

C. A catalyst is a substance that can create a new mechanism within a reaction in order to create a lower activation energy, and as a result it will increase the rate of the chemical reaction.

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11
Q

Consider the following reaction: N 2+ 3H2 ⇌ 2NH3 The rate of formation of NH3 is 3.0 mL/min . The rate of consumption of H2 is…. Select one: a. 1.5 mL/min b. 9.0 mL/min c. 3.0 mL/min d. 4.5 mL/min e. 2.0 mL/min

A

D

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12
Q

Consider the following experiments, each involving equal masses of zinc and 10.0 mL of acid. The rate of reaction in order from fastest to slowest is Select one: a. II>I >III b. I>II>III c. III>I>II d. III>II>I

A

C –> III would be the fastest as a result of the Zn being in powder form. An increase in surface area causes an increase in reaction rate. I would be fast as the high concentration of HCl would increase the reaction rate. II would be slowest as the concentration of HCl is low, and the surface area of Zn is small in the cube form.

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13
Q

In order for a collision between reactant particles to be successful Select one: a. there must be sufficient KE. b. the change in KE must be less than the change in PE. c. the system must be closed. d. a Δ H must be positive.

A

A

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14
Q

An activated complex has… Select one: a. high potential energy and is stable. b. low potential energy and is unstable. c. low potential energy and is stable. d. high potential energy and is unstable.

A

B. Activated complex are unstable, temporary structures with high potential energy that are formed when reactants are interacting . To get to a stable formation, bonds break and a lower potential energy structure results (the loss of potential energy goes to kinetic energy

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15
Q

Collision theory states that… Select one: a. very few reactions involve particle collisions. b. reactions do not require particles to collide. c. all collisions lead to chemical reactions. d. effective collisions lead to chemical reactions. e. most collisions lead to chemical reactions.

A

D

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16
Q

A proposed reaction mechanism for this reaction is: Step 1 H3O+ + I- → HI + H2O Step 2 H2O2 + HI → H2O + HOI Step 3 HOI + H3O+ → I- + 2H2O + I2 Step 4 I2 + I- → I3- In the above mechanism, which of the following is true for the overall reaction? a. H2O2 is a reactant b. HI is a catalyst c. H2O is an intermediate d. H3O+is a product

A

H202 is a reactant

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17
Q

Consider the following reaction: 2 H2O2(aq) → 2 H2O(l)+ O2(g) When 1.0 g of KI is added to the H2O2, bubbles of O2 are produced at an increased rate. When the reaction is complete, the mass of KI is 1.0 g. The KI is a …..

A

A CATALYST

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18
Q

How many grams of oxygen are in 14.6 g CO2?

A

14.6 g CO2 x 1 mol CO2 / 1(16.0) +2 (16.0) g CO2 x 2 mol O2/1 mol CO2 x 16.0 G O/ 1 mol O = 10.6 oxygen

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19
Q

How many moles of methane (CH4) needed to get 0.860 g of H?

A

0.860 g H x 1 mol H / 1.0 g H x 1 mol CH4 / 4 mol H = 0.215 mol CH4 2-step conversion

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20
Q

How many moles of H are in 6.0 mol of water?

A

6.0 mol water x 2 mol H / 1 mol water = 12 mol H 1-step conversion

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21
Q

A quantity of a substance or species can only be related to another substance via….

A

A MOLE

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22
Q

Moles of water in 1.8 grams of water?

A

1.8 g x 1 moles / 2(1.0g) + 1(16.0) = 0.10 mol of water

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23
Q

Calculate molar mass of 3.2 moles of Oxygen.

A

3.2 mol x 1 (16.0 g)/ 1 mol = 51 g

24
Q

What is the molar mass of a substance?

A

expressed in grams (it’s atomic, molecular, or formula mass)

25
Q

Avogadro’s number is …

A

6.022140857 × 1023 / mole of an an element

26
Q

Just like a dozen of anything is equal to 12, a mole of any element is equal to….

A

6.022140857 × 1023 a.k.a Avogadro’s number

27
Q

The Reaction Mechanism:

How many steps does this rxn have?

Which bump is the rate determining step?

Which bump also determines the overall Ea?

A

4 bumps = 4 steps

The highest bump.

the highest bump=measure from the highest bump to the beginning of the reaction at the upslope

28
Q

Define reaction mechanism?

A

the series of specific steps molecules take in order to complete a reaction

29
Q

What is activation energy?

A

minimum kinetic energy particles need to have a successful collision. (Ea energy)

30
Q

WHAT are 2 benefits to increasing the temperature 10 degrees?

A
  1. 3% increase in number of collisions due to increase in speed
  2. a roughly 100% increase in number of successful collisions (5% colliding to 10% to 20% etc)
31
Q

WHICH is faster? fewer or more reactants in a reaction?

A

FEWER

32
Q

WHICH is faster? homogenous reactions or heterogenous reactions

A

homogenous. aq + aq + aq = faster vs. aq + solid + gas = slower. Limited by surface area due to the solids.

33
Q

WHICH is faster: reactants in acqueous ionic form or reactants in acqueous molecular form? and 3 reasons WHY?

A

ionic form.

  1. bonds are already broken due to dissociation process
  2. low activation energy therefore
  3. oppositely charged ions are inclined to collide more frequently
34
Q

WHAT IS ENTHALPY?

A

heat content of a substance (total KE + PE of a substance). - if it goes down, heat was released from the substance. If it goes up, the substance absorbed heat

35
Q

CH3CH2CH3 + 5O2 + HEAT → 3CO2 + 4H2O

Endothermic or Exothermic?

A

endothermic

36
Q

CH3CH2CH3 + 5O2 → 3CO2 + 4H2O + heat

Exothermic or Endothermic?

A

EXOTHERMIC

37
Q

What is the ‘heat’ called that has been absorbed?

A

ENTHALPY

38
Q
A
39
Q

What is the ‘heat’ called that has been released?

A

ENTHALPY

40
Q

Exothermic or Endothermic?

2H2 (g) + O2 (g) → 2H2O (g)

ΔH = −483.6 kJ/mol of O2

A

EXOTHERMIC

41
Q

If ΔHΔHΔH is positive, then the reaction is ….

A

ENDOTHERMIC

42
Q

If ΔHΔHΔH is negative, the reaction is…

A

EXOTHERMIC

43
Q

Activation energy is not affected by these 3 factors:

..but it is affected by one thing. What is this?

A
  1. temperature
  2. concentrations
  3. surface area of a solid. Catalyst. Lowers the Ea.
44
Q

WHEN TWO ATOMS OR MOLECULES MOVE APART, POTENTIAL ENERGY ____, AND KINETIC ENERGY ____ (inc. or dec.)

A

decreases, kinetic

45
Q

WHEN TWO ATOMS OR MOLECULES MOVE TOGETHER, POTENTIAL ENERGY______ AND KINETIC ENERGY __________ (inc. or dec.)

A

increases, decreases

46
Q

WHAT IS THE ACTIVATION ENERGY?

A

the minimum amount of kinetic energy needed for a successful collision

47
Q

2 REQUIREMENTS THAT LEAD TO SUCCESSFUL COLLISIONS?

A
  1. favourable geometry (molecules are properly aligned)
  2. energy of collision (needs a certain amount of kinetic energy)
48
Q

WHAT IS COLLISION THEORY?

A

reaction rates depend on a) number of collisions in a set time b) number of collisions that actually produce results

49
Q

Which reacts faster: powder or small chunks of reactant?

A

powdered substances

50
Q

WHAT IS HETEROGENOUS IN CHEMISTRY?

A

reactants are in different phases or states

51
Q

WHAT IS HOMOGENOUS IN CHEMISTRY?

A

all reactants are in the same phase of state

52
Q

FOUR factors affecting the rate of the reaction? (not any K value, just the rate of the rxn)

A
  1. Increasing temperature,
  2. increasing concentrations of substances ( increasing surface area),
  3. adding a catalyst,
  4. increasing pressure
53
Q

What is the sequence from converting grams of substance A into grams of substance B?

A

grams A to moles A to moles B to grams B

54
Q

Calculate volume of H2 produced in 5.5 min, if 0.020 mL is produced per second?

A

6.6 mL of H2

55
Q

Calculate rate of reaction in mL of H2/seconds if 0.0036 L H2 is collected in 3.0 min.

A

0.020 mL H2/second

56
Q

WHAT IS A RATE EQUATION CONCERNED WITH?

A

a ratio of amount/pH/volume/concentration/other chemistry calculation and time

57
Q

WHAT IS CHEMICAL KINETICS?

A

the rate at which reactions occur and the factors that affect them

Chemistry 12 (4 decks)

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