New
New
Year 10
AQA
Foundation

Concentration and rate: practical using gas collection method

I can carry out a fair test to investigate how the rate of reaction depends on the concentration of a reacting solution.

New
New
Year 10
AQA
Foundation

Concentration and rate: practical using gas collection method

I can carry out a fair test to investigate how the rate of reaction depends on the concentration of a reacting solution.

Lesson details

Key learning points

  1. The changing rate of a reaction can be found by measuring the amount of gas produced as the reaction progresses.
  2. Increasing concentration of a reacting solution introduces more reactant particles, so they collide more frequently.
  3. When reacting excess acid with equal amounts of magnesium, the same volume is produced for all concentrations of acid.

Common misconception

Thinking that as the concentration of a solution in excess changes, so does the volume of gas produced.

The slide deck uses graphical data to show that the same volume of gas is produced when different concentrations are used, so long as the reacting solution is in excess.

Keywords

  • Rate of reaction - Rate of reaction is the speed with which a chemical reaction takes place.

  • Independent variable - The independent variable is the single variable that is changed in an investigation.

  • Dependent variable - The dependent variable is the single variable that is measured or observed in an investigation.

  • Control variables - The control variables are variables that are kept constant in an investigation.

To highlight to students that when we use magnesium strips of the same length we are assuming we have the same mass.
Teacher tip

Equipment

Conical flask, bung and delivery tube, water trough, measuring cylinder, timer, magnesium strips, different concentrations of hydrochloric acid and eye protection.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
How can we increase the rate of a reaction?
Correct answer: increase the surface area of a solid reactant
increase the volume of a reacting solution in excess
decrease the volume of a reacting solution in excess
Correct answer: increase the concentration of a reacting solution
decrease the concentration of a reacting solution
Q2.
According to the collision theory, what must happen for a reaction to occur?
Correct answer: particles must collide with sufficient energy
particles must collide with energy lower than the activation energy
particles must collide without any energy
particles must move in opposite directions
particles must move in opposite directions with the activation energy
Q3.
Which equipment can be used to measure the volume of gas in a rate of reaction investigation?
Correct answer: a gas syringe
a stopwatch
a thermometer
a pipette
Correct answer: an upturned measuring cylinder
Q4.
The rate of reaction can be defined as:
the total energy produced in a reaction
Correct answer: the amount of reactant used per unit time
Correct answer: the amount of product made per unit time
the time it takes for the reaction to start
the maximum temperature reached during the reaction
Q5.
If 10 grams of a reactant are used up in 5 seconds, what is the rate of reaction?
0.2 g/s
0.2 cm³/s
0.2 cm³/s²
Correct answer: 2 g/s
2 cm³/s
Q6.
What is activation energy?
the energy needed to form new chemical bonds
the energy released during the reaction
Correct answer: the minimum energy required for particles to react upon collision
the maximum energy that particles can have when colliding

6 Questions

Q1.
What does a graph of volume of gas produced against time show?
the total amount of reactants
Correct answer: the changing rate of the reaction
the pH change over time
the temperature change over time
Q2.
What is a common error when using a measuring cylinder to measure the amount of gas produced during a reaction?
incorrect pH readings
Correct answer: parallax error in reading volumes
using too much reactant
incorrect temperature measurement
Q3.
Why does increasing the concentration of a reacting solution increase the rate of reaction?
it decreases the activation energy
it increases the energy of the particles
Correct answer: it increases the frequency of collisions
it changes the state of the reactants
Q4.
Why does increasing the concentration of a solution increase the frequency of particle collisions?
more energy is added to the system
Correct answer: more particles are present in the same volume
the temperature increases
the pressure decreases
Q5.
When reacting excess acid with equal amounts of magnesium, how does the concentration of acid affect the volume of gas produced?
higher concentration produces more gas
lower concentration produces more gas
Correct answer: the same volume of gas is produced for all concentrations
no gas is produced
Q6.
To ensure a fair test when investigating how concentration affects rate of reaction, which of the following must be kept constant?
concentration of the reactant solution
Correct answer: surface area of the solid reactant
volume of gas produced
time taken for a certain volume of gas to be produced

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