FUNCHEM 14 - Collision theory & rate equation

Question 1

What is chemical kinetics?

Answer 1

Chemical kinetics is the study of three things:

1. the rates of chemical reactions
2. the factors that affect rates of chemical reactions
3. the mechanisms by which reactions occur

Question 2

What are the factors that affect the rate of reaction?

Answer 2

There are four factors that affect the rate of reaction:

1. concentration
2. temperature
3. catalysts
4. surface area

Question 3

What makes a collision an ‘effective collision’

Answer 3

There are three factors that make a collision an “effective collision”:

1. frequency of collisions
2. molecular orientation
3. energy of collisions

Question 4

What does the rate of reaction measure?

Answer 4

The rate of reaction measures how fast a reactant is consumed or how fast a product is formed. Measured in Mol/L/s.

Question 5

What are rate laws?

Answer 5

Rate laws explain the effect of concentration change on the rate of a reaction.

Question 6

What are the two types of rate laws?

Answer 6

The two types of rate laws are:

1. Differential Rate Law: describes the relationship between the rate of reaction and reactant concentration.
2. Integrated Rate Law: describes the relationship between reactant concentration versus time.

Question 7

What is reaction order?

Answer 7

Reaction order describes the relationship between reactant concentrations and reaction rate through experimental determination.

Question 8

What is first order reaction?

Answer 8

First order reaction happens in the case if the concentration of a reactant is doubled, then the rate of reaction also doubles. If the concentration of a reactant is tripled, then the rate of reaction also triples.

Question 9

What is second order reaction?

Answer 9

Second order reaction happens in the case if the concentration of a reactant is doubled, then the rate of reaction is quadrupled.

Question 10

Define reaction order in terms of the rate equation.

Answer 10

Overall reaction order is the sum of the powers of the reactant concentrations are raised in the rate law.

Question 11

What is a zero order reaction?

Answer 11

A zero-order reaction occurs when a change in the concentration of a reactant DOES NOT affect the rate of reaction.

Question 12

What is a pseudo-first order reaction?

Answer 12

When there is an excess amount of a reactant in a reaction, the concentration of that reactant virtually remains constant throughout the reaction.

Question 13

How does knowing the reaction order of a drug affect drug dosage?

Answer 13

Knowing the reaction order of a drug is important because it tells us at what rate a concentration of a drug will have a destructive effect on bacteria inside the body. For example, if the drug is zero order against the bacteria, no matter the concentration of the drug, the rate of destruction of bacteria will be constant.

Question 14

What is it important to know the half-life if a drug.

Answer 14

The half-life of a drug tells us the time required for a drug to reach 50% of its original concentration. By knowing this, it tells us after how long there will be not enough drug left in the body to carry out its pharmacological effect, so the frequency of dosages needs to be assigned accordingly.