Kinetics Worksheets

for

Chemistry 12

Mr. Iannone

Notes- double click on the lesson number and download Power Point Viewer if you do not have it.

Worksheets Quiz

1 Monitoring Reaction Rates WS 1 Q1

2 Factors that Change the Rate WS 2 Q2

3 Collision Theory WS 3 Q3

4 PE Diagrams WS 4 Q4

5 Mechanisms WS5 Q5

6 Lab: The Iodine Clock Reaction Web Review

7 Review Practice Test 1

Practice Test 2

8. Review Quizmebc

9. Test

Text book Hebden Read Unit I

The following workbook is designed to ensure that you can demonstrate your understanding of all aspects of the kinetics unit. The minimum expectation is that you do all of these questions by the due dates given by your teacher. Do the questions. Use your notes from class to assist you. Then after you have finished go to the web site to evaluate your work. Make a list of those things that you don’t quite understand and bring them to class. I will go over them as best as I can. There are other things that you should do to prepare for the test at the end of the unit. Remember, what you put into this course is what you will get out. There is no substitute for consistent effort and hard work. If you can’t do a question, get some help before the end of the unit, you need to know, understand, and remember everything. Good luck! I know you can do well in this unit. Web Site Address: sd34.bc.ca/schools/wjm/science/chem12

Ws #1 Monitoring and Calculating Reaction Rates

1. Read unit 1 of Hebden over the next week. “A” students should read it twice.

2. a) When measuring a property associated with a reactant in a reaction, does it increase or decrease?

Decrease as reactants are converted into products

2. b) When measuring a property associated with a product in a reaction, does it increase or decrease?

Increase as reactants are converted into products

3. Give three ways to measure the rate of the following reaction. State the specific properties that you would monitor and include units (amount is not a specific property). State if each property would increase or decrease. Describe in each case how you would calculate the reaction rate.

2HNO_3(aq) + Cu_(s) → NO_2(g) +H₂O_(l) + CuNO_3(aq)

The first one is done for you.

i) Mass of Cu Grams Decrease Rate = mass/time

ii) [HNO₃] M Decrease Rate = M/time

iii) Volume of NO₂ L Increase Rate = L/time

iv) [CuNO₃] M increase Rate = M/time

v) Mass of open container Grams Decrease Rate = mass/time

vi) Pressure of closed container KPa Increase Rate = Pressure/time

Any three of the above answers are fine.

Mass of copper (g) 3.26 2.93 2.61

Time (min) 5.0 7.0 9.0

4. Calculate the rate in units of (g Cu/min).

3.26 - 2.61 g Cu = 0.16g/min

9.0 - 5.0 min

5. Calculate the rate in units of (mole Cu/min).

0. 16g Cu x 1 mol = 0.0026 mol/min

min 63.5 g

6. Calculate the rate in moles HNO₃ consumed per second (remember that 2 moles are consumed per 1 mole of Cu).

0.0026 mol Cu x 1 min x 2 moles HNO₃ = 8.5 x 10^-5 moles/s

min 60s 1 mole Cu

7. Calculate the rate in units of (g/sec) for HNO_3.

8.5 x 10^-5 moles HNO₃ x 63.0 g = 0.0054 g/s

s 1 mole

Volume of NO₂ (mL) 10.0 11.5 12.7

Time (sec) 0.00 5.00 10.00

8. Calculate the rate in units of (mL NO₂/sec).

Rate = 12.7 - 10.0 ml = 0.27 ml/s

10.00 - 0.00 s

9. Calculate the rate in units of (L NO₂/min).

0.27 ml x 60s x 1L = 0.016 L/min

s 1 min 1000 ml

10. Calculate the rate in units of (moles NO₂/min) at STP.

0.0162 L x 1 mol = 7.2 x 10^-4 mol/min

min 22.4 L

11. Calculate the rate in units of (moles HNO₃/min) at STP (remember that 2 moles are consumed per 1 mole of NO₂)

7.23 x 10^-4 mol NO₂ x 2 moles HNO₃ = 0.0015 moles/min

min 1 mole NO₂

12. Calculate the rate of the following reaction:

2NO _(g) + 2H_{2 (g)} → N_{2 (g)} + 2H₂O _(g)

_0.080

_0.060

_0.040

_0.020

0.0 2.0 4.0 6.0 8.0 10.0 11.0 12.0

Rate = (0.080 – 0.020) moles = 0.0060 moles/s

(12.0 – 2.0) s

a) What is the rate in moles NO per second? 0.0060 moles/s

b) What is the rate in moles N₂ per second? 0.0030 moles/s

c) What is the rate in grams NO per min? 11 g/min

d) What is the rate in grams N₂ per hour? 3.0 x 10²g/h

13. Choose three properties that you could measure in order to monitor the rate of the following reaction.

Cu _(s) + 2AgNO_{3 (aq)} → 2 Ag _(s) + Cu(NO₃)_{2 (aq)}

Property Unit of Measurement Change

1. Mass Cu grams decrease

2. Mass Ag grams increase

3. Intensity [Cu⁺²] M increase

14. Calculate the rate of the following reaction in units of M/s:

Zn (s) + 2HCL (aq) → ZnCl_{2 (aq)} + H_{2 (g)}

Molarity of HCL (M) 0.612 0.813 1.05

time (seconds) 21.0 25.0 29.0

Rate = (1.05 - 0.612) M = 0.055 M/s

(29.0 - 21.0) s

15. Calculate the rate of the following reaction in L/min:

Zn (s) + 2HCL (aq) → ZnCl_{2 (aq)} + H_{2 (g)}

Volume of H₂ (L) 0.255 0.550 0.790

time (minutes) 1.0 2.0 3.0

Rate = (0.790 - 0.255) M = 0.27 L/min

(3.0 - 1.0) s

16. If 0.369g of HCl is neutralized with 0.250M NaOH in 25.0 seconds, what is the reaction rate in moles HCL /min.

0.369g x 1 mole

Rate = 36.5g = 0.0243 mole/min

0.41666 min

WS # 2 Factors That Change The Reaction Rate

Homogeneous reactions

- reactants are in the same phase (aq), (g) , or (l) and are thoroughly mixed.

Heterogeneous reactions

- reactants are in the two or more phases and are not thoroughly mixed (two solids do not mix).

Classify as Homogeneous or Heterogeneous:

1. Zn _(s) + 2 HCl _(aq) → H_{2 (g)} + ZnCl_{2 (aq)} heterogeneous

2. Ag⁺ _(aq) + Cl^- _(aq) → AgCl _(s) homogeneous

3. H_{2 (g)} + F_{2 (g)} → 2HF _(g) homogeneous

4. 2Al _(s) + 3I_{2 (s)} → 2AlI_{3 (s)} heterogeneous

The following four factors will increase the rate of a chemical reaction that is homogeneous:

1. Increasing the temperature.

2. Increasing the reactant concentration.

3. Adding a catalyst

4. Changing the nature of the reaction.

5. Increasing the pressure for gases

The above four factors as well as the two below will increase the rate of a heterogeneous reaction:

6. Increasing the surface area of a solid.

7. Agitation

Which factor will only increase the rate of a gaseous reaction?

8. Pressure

For each reaction specifically describe all of the ways to increase the reaction rate

(i.e.. increase[H₂]).

1. H_{2 (g)} + F_{2 (g)} → 2 HF _(g) This reaction is homogeneous so the first four factors will work.

Increasing the temperature

Increasing the pressure

Increasing [H₂] or [F₂]

Adding a catalyst

2. HCl _(aq) + NaOH _(aq) → NaCl _(aq) + H₂O _(l) This reaction is homogeneous so the first four factors will work.

Increasing the temperature

Increasing [HCl] or [NaOH]

Adding a catalyst

3. Zn _(s) + 2 HCl _(aq) → H_{2 (g)} + ZnCl_{2 (aq)} This reaction is heterogeneous most of the factors will work, except pressure- need a gaseous reactant..

Increasing the temperature

Increasing [HCl]

Adding a catalyst

Increasing the surface area of Zn_(s)

Agitation

4. State three examples of chemical reactions that are desired to be slow.

Food spoiling

Metal corrosion

Erosion

5. Give three examples of chemical reactions that are desired to be fast.

Combustion of gasoline in automobiles

Industrial chemical production

Cooking food

The combustion of gasoline in a car engine; while accelerating.

6. List all of the ways to increase the rate of the following reaction:

H₂O_{2 (aq)} → H_{2 (g)} + O_{2 (g)}

Increasing the temperature

Increasing [H₂O₂]

Adding a catalyst

I. Homogeneous reactions are generally faster than heterogeneous- the reactants are mixed better and therefore there are more collisions between reactant particles.

HCl _(aq) + NaOH _(aq) → NaCl _(aq) + H₂O _(l)

is faster than

Zn _(s) + 2 HCl _(aq) → H_{2 (g)} + ZnCl_{2 (aq)}

II. Simple ionic reactions (where there are no bonds to break) are generally faster than more complex ionic reactions (where there are bonds to break).

Pb⁺² _(aq) + 2Cl^- _(aq) → PbCl_{2 (l)}

is faster than

2Na⁺ _(aq) + 2ClO^- _(aq) → 2Na⁺ _(aq) + 2Cl^-_(aq) + O_{2 (g)}

1. Indicate the faster and slower reaction and explain why.

a) 2Al _(s) + 3I_{2 (s)} → 2AlI_{3 (s)}

Heterogeneous reaction with bonds to break will be slow.

b) Ag⁺_(aq) + Cl^-_(aq) → AgCl _(s)

Homogeneous reaction with no bonds to break will be fast.

2. Indicate the faster and slower reaction and explain why.

a) 2Al _(s) + 3I_{2 (s)} → 2AlI_{3 (s)}

Slow. The reaction is heterogeneous (two solid do not mix) with bonds to break.

b) 2Na⁺ _(aq) + 2ClO^- _(aq) → 2Na⁺ _(aq) + 2Cl^-_(aq) + O_{2 (g)}

Faster. The reaction is homogeneous.

3. Indicate the faster and slower reaction and explain why.

a) 3Ba⁺²_(aq) + 2PO₄^-3 _(aq) → Ba₃(PO₄)_2(aq)

Faster. The reaction is homogeneous and simple ionic with no bonds to break.

b) Cu_(s) + 2Ag⁺_(aq) → Cu⁺² _(aq) + 2Ag _(s)

Slow. The reaction is heterogeneous and the Cu_(s) bonds need to be broken.

Ws # 3 Collision Theory

1. Chemical reactions are the result of collisions between reactant particles, where bonds are broken and new ones form.

2. A successful collision requires sufficient energy and favorable geometry.

3. Describe as fast, medium or slow. Explain!

i) 2 H_{2 (g)} + O_{2 (g)} → 2 H₂0 _(l) (room temperature)

Slow. Gas reactions are slower than aqueous.

ii) 2 Ag⁺ _(aq) + CO₃^2- _(aq) → Ag₂CO_{3 (s)}

Fast. Homogeneous reaction simple ionic- there are no bonds to break

iii) 2 HCl _(aq) + Na₂CO_{3 (aq)} → CO_{2 (g)} + 2 NaCl _(aq) + H₂0 _(l)

Medium. Homogeneous complex reaction - there are bonds to break.

4. i) Describe how you would measure the rate of the reaction :

Zn _(s) + 2 HCl _(aq) → ZnCl_{2 (aq)} + H_{2 (g)}

Measure the decrease in Zn mass.

Measure the increase in H₂ gas volume.

Measure the mass of an open container which decreasing due H₂ escaping.

ii) List four ways to increase the rate.

Increasing the temperature

Increasing [HCl]

Adding a catalyst

Increasing the surface area of Zn_(s)

Agitation

5. A 10 °C temperature increase frequently doubles the rate of a slow reaction because:

a) The temperature has doubled.

b) The PE of the colliding particle has doubled.

c) The KE of the colliding particle has doubled.

d) The fraction of particles with sufficient KE to react has doubled.

6. Both collisions A and B have the same KE. Which collision is successful and explain why.

Before Collision After Collision

A)

B)

Collision B was successful due to favourable geometry.

7. Use the collision theory to explain how each factor increases the reaction rate.

i) Increasing temperature i) more collisions and harder collisions

ii) Increasing [reactants] ii) more collisions

iii) Increasing surface area (solid) iii) more collisions

iv) Agitation of a heterogeneous reaction iv) more collisions

v) Adding a catalyst v) lower Ea & low energy collisions are successful

8. Explain why collision A was successful while collision B was unsuccessful.

Before Collision After Collision

A)