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Rates of Reaction Summary
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1
Question
What is the main purpose of rates of reaction in chemistry?
Answer
To measure how quickly reactions proceed (change in quantity over time)
2
Question
What variables can increase the rate of a chemical reaction?
Answer
Temperature, concentration, surface area, catalyst usage
3
Question
What is the effect of a catalyst on a reaction rate?
Answer
Speeds up the reaction without being consumed
4
Question
Why does the rate of a reaction typically decrease over time?
Answer
Reactants are consumed, reducing collision frequency
5
Question
In a gas-volume experiment, what does the syringe setup measure?
Answer
Volume of gas produced (and indirectly rate)
6
Question
Why is a fair test important when studying reaction rates?
Answer
To ensure only one variable changes at a time and results are valid
7
Question
What is a reaction progress graph used for?
Answer
To show how mass or gas production changes with time during a reaction
8
Question
What does the term end-point of a reaction refer to?
Answer
The point where the reaction essentially stops (no further change)
9
Question
Which experimental observable indicates the fastest rate at the start of a reaction?
Answer
Steepest initial slope of the reaction progress curve
10
Question
What is the slope of a reaction progress graph most directly related to?
Answer
The rate of gas evolution or reaction progress.
11
Question
What does a leveling off of a reaction progress graph indicate?
Answer
The reaction has stopped; no more product is formed.
12
Question
Which measurement is described as a method for monitoring a reaction in the provided text?
Answer
Measuring the mass of gas produced.
13
Question
List the variables affecting the rate of a chemical reaction given in the text.
Answer
Temperature, concentration, particle size/surface area, presence of a catalyst.
14
Question
What is the purpose of making a fair test in rate experiments?
Answer
To control all variables except the one being investigated.
15
Question
In the three experimental set-ups for the acid and marble chips, what would be measured in part (a)?
Answer
Mass change as the reaction proceeds.
16
Question
In the three experimental set-ups for the acid and marble chips, what would be measured in part (c)?
Answer
Volume of gas produced.
17
Question
Which factor from the grid is responsible for increasing the reaction rate when adding a catalyst?
Answer
Catalyst introduction (D).
18
Question
What factor change corresponds to a faster reaction: decrease in particle size, decrease in temperature, increase in concentration, or adding a catalyst?
Answer
Adding a catalyst.
19
Question
From the table, what factor increases the rate when it changes in (B) cooling?
Answer
Decrease in temperature reduces rate; the factor is temperature.
20
Question
In Experiment 1.1.2, what is the independent variable?
Answer
Particle size.
21
Question
What is the dependent variable in Experiment 1.1.2?
Answer
Speed the gas is evolved.
22
Question
What apparatus is used to measure gas volume in the marble chips experiment?
Answer
Gas syringe (or measuring cylinder via gas collection).
23
Question
What is the word equation for the reaction between hydrochloric acid and calcium carbonate?
Answer
Calcium carbonate + hydrochloric acid → calcium chloride + carbon dioxide + water.
24
Question
In the context of the marble chips experiment, what does a mass decrease of the flask indicate?
Answer
Mass of carbon dioxide gas left the flask.
25
Question
What does a steeper initial slope on the reaction progress graph signify about reactant concentration?
Answer
Higher reactant concentration leading to faster rate.
26
Question
According to the provided results, which experiment (1 or 2) showed a faster initial rate of gas evolution?
Answer
Experiment 1.
27
Question
Which experiment showed the faster initial rate of gas evolution and how is this reflected in the graph?
Answer
Experiment 1; steeper initial slope indicates faster gas production
28
Question
In Experiment 1 and Experiment 2, what is the final total gas volume evolved?
Answer
Experiment 1: 55 cm³; Experiment 2: 55 cm³
29
Question
If both experiments end at the same gas volume, what does this imply about the amount of reactant used in each?
Answer
Same amount of marble chips used
30
Question
What indicates that a reaction has completed on a gas evolution graph?
Answer
The gradient becomes zero (no further gas is produced)