CH 18 - Reaction Rate

Question 1

Reaction Rate

Answer 1

Change in concentration of product/reactant per unit time.

Question 2

Pressure - R.R

Answer 2

Increase the concentration of reactants, which leads to higher frequency of collisions which leads to a higher number of successful collisions. Therefore, the reaction rate is increased.

Question 3

Temperature affect on R.R

Answer 3

Increase in average kinetic energy of reactants which leads to a higher frequency of collisions as well as collisions with = to or greater energy than the Ea. Therefore, r.rate is increased.

Question 4

Catalyst - R.R

Answer 4

• Susbtances which increase r.r without being consumed themselves in the reaction. Provide an alternative energy pathway with a lower Ea, therefore increasing the proportion of collisions with = to or greater than energy than the Ea. This means higher number of successful collisions, as R.rate is increased.

Question 5

For a reaction to occur, particles must:

Answer 5

• Collide with one another
• Collide with sufficient energy to break the bonds within the reactants
• Collide with the correct orientation to break the bonds within the reactants to allow for products to form.

Question 6

Activation energy:

Answer 6

The min. energy required to break the bonds within reactants in order for a reaction to occur.

Question 7

Transition State

Answer 7

Unstable state in which bonds within reactants are breaking and product bonds are starting to form.

Question 8

Concentration - R.R

Answer 8

More reactant particles per given amnt. of solution, meaning increased frequency of collisions and therefore a higher number of successful collisions.

Question 9

Surface Area - R.R

Answer 9

Greater number of exposed particles, leading to a higher frequency of collisions. Leads to increased number of succ. collisions, therefore increasing R.R.

Question 10

Maxwell-Boltzmann Distribution Graph

Answer 10

Distribution of energies of particles in a sample at a certain temp.

Question 11

Types of Catalysts:

Answer 11

1. Heterogenous: diff. physical state as reactants/products.
2. Homogenous: same physical state as reactants/products.

Question 12

Nanoparticles as Catalysts

Answer 12

• Increased surface area increases contact between the catalyst and reactants, therefore more catalytic reactions can occur in any given time.

Question 13

Catalytic Car Converters

Answer 13

Convert CO and NO into Co2 and N + O2. (created from car engine). Hydrocarbons are combusted to produce CO2 and H2O.

Made of a mix of metals such as rhodium, palladium and have millions of pores to increase SA.

Lead can’t be used as it coats the converter, so the other parts can’t come into contact with it, therefore making it ineffective. No more lead now as it is toxic and causes health problems.

Question 14

What is meant by a successful collision?

Answer 14

Bond is broken or formed - more than min. energy required and correct orientation.