Starter quiz
- If a reaction effervescences, what does this tell us about the state of one of the products made?
- the product is a solid
- the product is a liquid
- the product is a gas ✓
- the product is a solution
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- If a product in a chemical reaction is a gas, how can we measure the volume of gas produced in a given time?
- using a thermometer
- using an inverted measuring cylinder ✓
- using a gas syringe ✓
- using a light sensor
- using chromatography
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- When a chemical reaction takes place in a closed system, which of the following may be observed?
- the volume of the reactants increases
- a colour change of the reaction mixture ✓
- change in mass of the reaction mixture
- bubbles forming as a gas is produced ✓
- a precipitate forming ✓
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- How can we calculate the rate of reaction?
- divide the change in temperature by the change in time
- multiply the initial concentration of reactants
- divide the change in volume of reactants by the change in time ✓
- subtract the final concentration of reactants
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- Match the key terms to the correct definition.
- accurate⇔values that are close to the true value ✓
- precise⇔values that lie close to each other ✓
- repeatable⇔using the same method to obtain the same/similar results again ✓
- reproducible⇔another person uses the same method to obtain the same/similar results ✓
- A reaction produces 5 cm³ of gas in 10 seconds. What is the rate of reaction?
- 5 cm³
- 10 seconds
- 0.5 cm³/s ✓
- 5 cm³/s
- 50 mph
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Exit quiz
- Which equipment is suitable for measuring the percentage of light transmitted through a reaction producing a precipitate?
- thermometer
- stopwatch
- upturned measuring cylinder
- gas syringe
- light sensor ✓
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- When is an upturned measuring cylinder suitable for measuring gas volumes in a reaction?
- when the reaction produces small volumes of gas rapidly
- when the reaction produces large volumes of gas at a slow rate ✓
- when the gas needs to be collected over water
- when the gas produced has a colour
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- What should be considered when selecting the size of measuring equipment for gas volumes?
- it should be smaller than expected to save space
- it should be larger than expected to avoid overflow
- it should be close to the expected volume of gas produced ✓
- it should be adjustable to accommodate different reactions
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- Why are gas syringes considered ideal for measuring small volumes of gas with high precision?
- they are less expensive than other equipment
- they are transparent and easy to read
- they have small graduations and are designed to prevent gas escaping ✓
- they can measure gases at high temperature
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- If a reaction in an open system produces a gas, what can be measured to determine the rate of reaction?
- the temperature change of the reaction mixture
- the color change of the reaction mixture
- the decrease in mass of the reaction mixture over time ✓
- the increase in volume of the reaction mixture
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- In a reaction that produces a gas, what happens to the volume of gas produced per second as the reaction progresses?
- it increases continuously
- it remains constant
- it increases and then remains constant
- it decreases ✓
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Choosing the correct equipment is crucial for obtaining accurate and reliable results.
- An upturned measuring cylinder is suitable for reactions producing large volumes of gas at moderate rates.
- Gas syringes are ideal for measuring small volumes of gas with high precision.
- The size of the measuring equipment should be close to the expected volume of gas produced.
- Light sensors can be used to measure the percentage of light transmitted through a reaction producing a precipitate.
Common misconception
Thinking that precise and accurate are the same thing.
It may help to draw a bullseye target board. Precise results will all be close to each other but may not be near the bullseye. Accurate results will be near the bullseye but may be more scattered if they are not precise.
Keywords
Rate of reaction - Rate of reaction is the speed with which a chemical reaction takes place, measured by the amount of a reactant used or amount of product formed in a given time.
Volume - Volume is how much 3D space matter occupies. It is usually measured in cm³.
Accurate - Accurate measurements are those that are close to the true value.
Precise - Precise measurements have very little spread from the mean value. They are values that lie close to each other.
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