Rates of Reactions

Instructions

Creating notes

In this lesson you will try the questions first and then move on to the notes. Use educated guesses and take note of whats being asked so you can better take down the information you need later in the slides

Copy down the headings and notes on each slide. Always highlight key information. Make sure to label your diagrams.

When answering the questions use your notes and your book Chapter 20 for help

Multiple Choice

Which of the following would increase the rate of a chemical reaction?

• Freezing the chemicals

• Increasing the temperature of the reagents

• Removing a catalyst

• Using less chemicals

Multiple Choice

Which of the following would increase the rate of a chemical reaction?

• Removing a catalyst

• Diluting the chemicals

• Decreasing the temperature

• Adding a catalyst

Multiple Choice

Which colour on the graph would represent the solution with the higher temperature?

• Red

• Blue

• None

• Both

Multiple Choice

Which colour on the graph would represent the solution with a catalyst?

• Red

• Blue

• Both

• None

Multiple Choice

Which of the following would increase the rate of CO2 made using marble chips and HCl?

• Lowering the temperature

• Crushing the marble chips

• Using less acid

• Using bigger marble chips

Multiple Choice

Which of the following lines represents the chemical with the lower concentration?

• Red

• Blue

• Both

• None

Multiple Choice

A chemical reaction in which energy is absorbed is ______________.

• an endothermic reaction

• an exothermic reaction

• a single replacement reaction

• a double replacement reaction

Multiple Choice

A chemical reaction in which energy is released or removed is ______________.

• endothermic

• exothermic

Multiple Choice

What is the activation energy?

• The energy of the products
• The energy of the reactants
• The minimum energy needed by the reactants to form the products.
• The energy lost in the reaction

Multiple Choice

What kind of reaction is this?

• Endothermic
• Exothermic
• Cannot be determined

Multiple Choice

_____ reactions usually feel hot!

• endothermic

• exothermic

Multiple Choice

____ reactions usually feel cold.

• endothermic

• exothermic

Multiple Choice

The graph above is from which type of reaction?

• Endothermic reaction

• Exothermic Reaction

Multiple Choice

The graph above is from which type of reaction?

• Endothermic reaction

• Exothermic reaction

Multiple Choice

Solid --> liquid --> gas is what type of reaction?

• endothermic

• exothermic

• catalytic

• inhibited

Multiple Choice

What type of reaction occurs in a hand warmer

• exothermic
• endothermic

Multiple Choice

What does a catalyst do in a chemical reaction?

• Increases the activation energy

• Decreases the activation energy

• Increases the temperature

• Decreases the temperature

Multiple Choice

What is the energy that the reactants need in order to collide successfully called?

• Activation energy

• Kinetic energy

• Chemical energy

• Potential energy

Multiple Choice

What factor can be used to control the rate of a reaction by increasing the surface area of a solid reactant?

• Increasing the concentration of a reactant in solution

• Increasing the surface area of a solid reactant

• Increasing the energy (heat)

• Increasing the pressure of a gaseous reactant

Multiple Choice

What is the concept of energy as the ability to do work?

• Ability to do work over time

• Ability to do work over distance

• Ability to do work over area

• Ability to do work over volume

Multiple Choice

What factor affects the rate of a reaction by changing the concentration of a reactant in solution?

• Increasing the temperature

• Increasing the pressure of a gaseous reactant

• Increasing the surface area of a solid reactant

• Increasing the concentration of a reactant in solution

Multiple Choice

What is the concept of activation energy in a chemical reaction?

• Energy released during a reaction

• Energy absorbed during a reaction

• Energy required to initiate a reaction

• Energy stored in the reactants

Multiple Choice

A temperature increase causes the particles ......

• to slow down

• move faster

• collide higher

• in the right order

Multiple Choice

How does a catalyst work in speeding up a reaction?

• By lowering the activation energy or reaction

• by giving them more energy

• by making them more available

Multiple Choice

The following graph shows two different reaction pathways for the same overall reaction at the same temperature. Which pathway is slower and why?

• Red, because the activation energy is larger
• Blue, because the activation energy is lower
• both reaction progress at the same rate

Multiple Choice

The ______________is required to break the bonds of the reactants.

• Carbonic energy

• Activation energy

• Plutonic energy

• Energi Gaib

Multiple Choice

The SI unit of heat and energy is the __________.

• calorie
• heat
• joule
• watt

Multiple Choice

In an endothermic reaction the products have 

• more energy than the reactants
• less energy than the reactants
• the same energy as the reactants
• no energy

Multiple Choice

Which of the following would increase the rate of CO2 made using marble chips and HCl?

• Lowering the temperature

• Crushing the marble chips

• Using less acid

• Using bigger marble chips

Multiple Choice

Which graph shows the effect of increasing temperature on the rate of reaction of calcium carbonate with dilute hydrochloric acid?

Multiple Choice

In which experiment is the rate of reaction between hydrochloric acid and calcium carbonate slowest? 

• A
• B
• C
• D

What is the ‘rate of reaction’?

The rate of a chemical reaction tells us how quickly a chemical reaction happens.
One of the slowest rates of reaction is the rusting of iron. A really fast reaction is
an explosion, which is all over in a fraction of a second.

What is the ‘rate of reaction’?

In industry it is very
important to know how
long it will take for a
reaction to occur.
Reactions can take
varying amounts of time
from start to finish, so
chemists measure how
many reactants are used
up and how much
product is formed in a
certain time.

Rate at which the reactants are
used up or the product is formed

What is particle theory?

During a chemical reaction the particles in
the reactants are moving all the time. The
rate of a reaction simply depends on how
often and how hard the reacting particles
collide with each other.

For the particles to react they must collide
with enough energy to break the bonds in
the molecules. Once the bonds are broken
the atoms can rearrange to make the
products.

Increasing the rate of a reaction involves
increasing the number of successful collisions
between the reacting particles. There are a
number of factors that affect the behaviour
of particles and have an overall effect.

Particle theory – an
unsuccessful collision

Particle theory – a
successful collision

What happens to the rate of the reaction when you stir
the solution?

Stirring the solution keeps the reactant particles in motion, increasing the chances
of collisions and increasing the rate of reaction.

What happens to the rate of reaction as you increase
the temperature?

When you raise the temperature the particles have more energy so they move
around more quickly. This results in more collisions in a certain time, and so
reactions get faster as we raise the temperature.

As particles get more energy they move at a greater speed,

and so there are more collisions and reactions get faster

Reaction at 30°C

Reaction at 40°C

What happens to the rate of reaction when you increase
the surface area?

Surface area is the measure of how much surface (of the reactants) is exposed.
When a large piece of solid material is cut into smaller pieces its surface area is
increased. The smaller the particle size, the greater the surface area on which the
reaction takes place, and so the faster the reaction.

You increase the surface area of the potato each time you cut it into smaller pieces

What happens to the rate of reaction when you increase
the surface area?

The effect of increasing surface area on the rate of reaction: the steepest part of
the curve is at the start, hence the fastest part of the reaction, but the curve
becomes less steep as the reaction slows down and eventually becomes flat,
indicating the end of the reaction

What happens to the rate of reaction as you increase
the concentration of the acid?

When you increase the concentration, you increase the number of particles,
which results in more collisions in a certain time and so you get an increase in
rate of reaction (that is, the reaction gets faster).

What happens to the rate of reaction as you increase
the concentration of the acid?

The effect of increasing concentration on the rate of reaction: the reaction is
fastest at the start (steep curve), gradually becoming slower as the reaction
proceeds. The curve on the graph goes flat when the reaction is complete

Light sticks

Light sticks produce light because of a chemical reaction. Dropping a light stick
into hot water makes it glow more intensely, demonstrating that the reaction
occurs faster at higher temperatures.

What is the effect of using a catalyst?

Transition metals lie between group 2 and group 3 in the periodic table. Some
well-known transition metals are iron, copper, chromium, nickel and gold.
Transition metals and their compounds are important catalysts. (A catalyst is a
substance which alters the rate of a reaction without getting used up.) How will
a catalyst affect the rate of reaction?

What is the effect of using a catalyst?

Activation energy is the
minimum amount of
energy that reactant
particles must
have in order for them
to react.

When you add a catalyst
it lowers the activation
energy; this makes it
easier for the particles to
react, so there is an
increase in the rate of
reaction.

How a catalyst works

Biochemical reactions

There are several factors that can affect the rate of biochemical reactions, such as,
respiration and photosynthesis (see chapter 10). The main factors that affect the
rate of photosynthesis are light intensity, carbon dioxide and temperature.

Photo credits

•Shutterstock

•Science Photo Library

•Michael Philips

•Compuscript