Download Text 6- Pre and Post Reading Activities Reaction Kinetics

Grade 10 Science Related Reading/Chemistry
Chemistry Gr10
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Class:____________________
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Chlorinated
hydrocarbons
Chemical
Reactions
can save lives
and their uses
Task 1 – Pre-Reading Activity
Reaction rate relates to how fast/slow a reaction takes place.
For example, the burning of a fire is a fast reaction, whereas corrosion is a slow reaction
List some examples of fast and slow reactions that you may have come across in your life
Fast Reactions
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Slow Reactions
Task 2 – Reading Activity
Chemical Reactions which save lives:
The rate of a reaction is the speed at which a reaction happens. If a reaction has a low rate,
that means the molecules combine at a slower speed than a reaction with a high rate.
Some reactions take hundreds, maybe even thousands, of years while others can happen in
less than one second. The rate of reaction depends on many factors like the concentration
of the reactants, particle size, temperature, pressure of gaseous reactants, surface area of
solid reactants and the presence of a catalyst.
It can be measured as the 'rate of formation of product' or the 'rate of removal of reactant'.
The speeds of reactions are very varied.
Rusting is a ‘slow’ reaction, you hardly see any change looking at it!
The weathering of rocks is an extremely very slow reaction.
The fermentation of sugar to alcohol is quite slow but you can see the carbon dioxide
bubbles forming in the 'froth' in a laboratory experiment
A faster reaction example is magnesium reacting with hydrochloric acid to form magnesium
chloride and hydrogen or the even faster reaction between sodium and water to form
sodium hydroxide.
Combustion reactions e.g. when a fuel burns in air or oxygen, is a very fast reaction.
Have you ever been in a car collision ? Your life could one day be saved by a car air bag.
When a car fitted with an air bag is in a crash , a sensor at the front of the car detects the
sudden slowing down and triggers the ignition of a mixture of chemicals. The chemicals
react together to release a large volume of Nitrogen gas . The nitrogen inflates a nylon bag
located in the steering wheel . Your head hits the bag and not the wheel. Some gas escapes
through small holes in the bag. This further softens the impact . All of this happens in less
than a second.
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The gas generating chemicals are a mixture of sodium azide(NaN3) Potassium nitrate(V)
(KNO3) and Silicon dioxide (SiO2). When ignited the sodium azide decomposes to produce
Nitrogen gas and Sodium metal.
2NaN3 (s)
2Na(s) + 3N2(g)
The Sodium reacts with the potassium nitrate to release more nitrogen.
10Na(s) + 2 KNO3(s)
K2O (s) + 3 N2 (g)
Key Vocabulary
rate
reaction
collision
triggers
ignition
chemicals
temperature
pressure
Particle size
concentration
Surface area
catalyst
A. Give the synonyms for the following terms:
1.
2.
3.
4.
Term
rate
collision
triggers
ignition
Synonym
B. What is the meaning of rate of a reaction?
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C. List the factors that affect the rate of reactions:
Factors that affect the
Rate of a Reaction
D. Classify the following reactions as fast or slow.
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Task 3 – Post Reading Activity
1. Order the following processes to show how car airbags function.
2. Write the chemical reactions that cause the air bags to function.
3. Explain one way in which you could affect the speed of this reaction.
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