Name__________________________________________period____________IB Chapter 6
Kinetics
1. Define the term rate of reaction.
The measure of the amount of reactants being converted into products per unit amount of time
2. What are some ways that we can measure the rate of a reaction?
Measure the change in volume of gas produced, measure the change in mass, measure changes in transmission
of light, measure the change in concentration using a titration, measure the change in concentration using
conductivity,
3. Describe the collision theory
For a reaction to occur, reactants need to collide with enough energy (activation energy) and with the correct
orientation
4. Describe the effect of a catalyst on a chemical reaction.
A catalyst speeds up a reaction by lowering the activation energy
5. Define the term activation energy
Minimum amount of energy which particles must have before they are able to react
6. It is found that a 10 oC increase in temperature roughly doubles the rate of many chemical reactions. If a reaction
takes 20 seconds at 40oC, how long would it take at 60oC?
5 seconds
7. Use the collision theory to explain why each factor (temperature, concentration, pressure, particle size) alters the
rate of a reaction.
Temperature- reacts hit with more energy and more frequently
Concentration- more collisions will occur
Pressure- more collisions will occur
Particle size- more collisions will occur
8. It has been found that rates are more rapid at the beginning of a reaction than toward the end, assuming the
temperature is constant. Explain why.
As a reaction proceeds, the amount of reactants decrease (concentration decreases) so the reaction slows
down.
9. Would you expect a packet of sugar to dissolve faster in hot tea or iced tea?
Hot tea
10. For each of the following pairs, choose the substance or process you would expect to react more rapidly.
a. Granulated sugar or powdered sugar
b. Zinc in HCl at 298 K or zinc in HCl at 410 K
c. 5 g of thick platinum wire or 5 g of thin platinum wire
11. Explain why there is a danger of explosion in places such as coal mines, saw mills, and grain elevators, were large
amounts of dry, powdered combustible materials are present.
There is high surface area of the combustible material so a reaction can occur faster
12. For each energy diagram below, label reactants, products, ∆H, Ea, and tell if it is endothermic or exothermic.
13. How would each of the energy diagrams in the previous problem change if a catalyst were added to the reaction?
(show using dashed lines)
Try all the exercises and practice questions in Chapter 6
Review:
(check answers in back of book)
14. What is the concentration of nitric acid if 15 cm3 of it is titrated with 25 cm3 of 0.67 mol dm-3 aluminum hydroxide?
3.35 mol dm-3
15. The heat of solution for silver nitrate is +22.8 kJ/mol.
a. Is dissolving silver nitrate endothermic or exothermic? endothermic
b. As silver nitrate dissolves, what change occurs in the temperature of the solution? increases
c. Is silver nitrate more likely to dissolve in oil (nonpolar) or water (polar)? Water
16. What is the concentration of a solution if 40.3 g of potassium cyanide are dissolved 450 cm3 of solution?
1.1 mol dm-3
17. How many grams of sodium hydroxide are in 210 cm3 of a 0.67 mol dm-3 solution?
5.6 g
18. How do gases compare with liquids and solids in terms of distance between their molecules?
Gas molecules are much farther apart
19. Which of the following gases would have the greatest kinetic energy, He at 20 °C or He at 50 °C?
20. What is sublimation? Is it endothermic or exothermic?
Changing a solid to a gas; endothermic
21. Is melting endothermic or exothermic?
Endothermic
22. Is condensation endothermic or exothermic?
Exothermic
23. Label each of the following as exothermic or endothermic and tell if the temperature would increase or decrease
when the reaction occurs.
a. 2H2 + O2  2 H2O ∆H = 483.6 kJ
endothermic; decrease
b. 2NO  N2 + O2
∆H = -90.29 kJ exothermic; increase
24. What type of intermolecular forces does each of the following have?
a. CH4
b. NH3
c. H2O
van der waals
hydrogen bonding
hydrogen bonding
d. H2S
dipole-dipole
25. Which of the following molecules in the previous question would have the lowest boiling point?
CH4
26. If 6.5 moles of hydrogen reacts with silver phosphate, how many grams of silver will be produced?
1400 g Ag
27. If M represents a group 1 metal, what is the formula for the compound formed by M and oxygen?
a. MO2
b. M2O
c. M2O3
d. M3O2
28. When do electrons release photons(packets of energy)? When the electrons:
a. move to higher levels of energy
b. return to their original energy level
c increase orbital speed around the nucleus
d. are released by the atom
29. Which of the following elements has the strongest attraction for electrons?
a. boron
b. aluminum
c. oxygen
d. sulfur
30. As the elements in Group 17 are considered in order of increasing atomic number, the chemical reactivity of each
successive element:
a. decreases
b. increases
c. remains the same