Rate of reaction Flashcards
What is one of the slowest rates of reaction?
What is one of the moderate rates of reaction?
What is really fast reaction?
The rusting of iron
A metal with an acid like magnesium, to produce a gentle stream of bubbles.
An explosion
What four things does the rate of reaction depend on?
Temperature
Concentration (or pressure of gases)
Catalyst
Surface area of solids (or size of solid pieces)
The faster the RofR the quicker it is …. . So the line on the graph would go … …… .
finished!
flat earlier
What are the axes for a RofR experiment? Describe a graph for a slow RofR... Describe a graph for a medium RofR... Describe why a graph for a medium RofR finishes before number 2... Describe a graph for a fast RofR...
Y= Amount of product evolved, x= time
Shallow gradient, not steep, levels of after a long time.
Steeper slope leveling off sooner
It has a catalyst, increased temp, concentration, the solid is in smaller bits.
A very high steep curve that starts to level off quickly but takes a while to stop reacting
What are the three ways to measure rate of reaction?
Precipitation
Change in mass
The volume of gas given off
What are the two ways rate of reaction can be Observed?
Either by measuring how quickly the reactants are used up or how quickly the products are formed - the easier method
What is the equation for the rate of reaction?
rate of reaction = amount of product used or formed / time
What are the five steps of a precipitation reaction?
- What is a precipitation reaction?
- What you do…
- What does what mean about the reaction?
- But it only works when?
- But what’s the problem with the result?
- When the product of a reaction is a precipitate which clouds the solution
- Observe the mark made on paper under the beaker and time how long it takes for it to fully disappear
- The quicker the mark disappears the faster the rate of reaction
- The original solution is relatively see through
- The result is very subjective - different people might not agree over the time it was completely covered, so repeat to make sure.
What are the five steps of a change in mass test for rate of reaction?
- What test could you test on what equipment?
- So what happens..?
- What does what mean about the reaction?
- What’s good about this test for your work?
- Why is this method the most accurate? But…
- One that gives of gas on a mass balance
- As the gas is released the disappearing mass can be measured by the balance
- The quicker the reading drops the faster the reaction
- RofR graphs are easy to plot from the results
- Because the balance is very accurate … but the gas is released straight into the room
What are the four steps of a ‘volume of gas given off’ test for rate of reaction?
- What does this test involve?
- How is the rate of reaction measured from the test?
- What graph could you plot?
- Why is this method the most accurate? But…
- Using a gas syringe to measure the volume of gas released
- The more gas given off in the time interval the faster the reaction
- Gas volume against time elapsed, for an rofr graph
- Gas syringes usually are accurate to the nearest millimeter. If the reaction is too vigorous you can easily blow the plunger out of the syringe.
What are the four ways to measure the effect of factors on rate of reaction?
What reactants on which factor?
Reaction of HCl and marble chips - surface area
Reaction of Mg and dilute HCl - concentration
Reaction of sodium thiosulphate and HCl - temperature
Thermal decomposition of hydrogen peroxide - catalyst
What reaction can be done to measure the effect of surface area on rate of reaction?
How is the reaction done?
What do you do for the next repeat?
What do you do with the results? Label how?
Reaction of HCl and marble chips
Measure the volume of gas evolved when marble chips are placed in a conical flask with a gas syringe in hydrochloric acid, and take readings of the amount of gas at regular time intervals.
Use the same volume of acid and the same mass of marble chips but crunch them up more, then repeat with powdered marble.
Make a table of readings and plot them as a graph, time on the x axis, volume of gas on the y. The different lines should be labeled with the size of the marble chips.
A graph shows the effect of using finer particles of solid in a reaction showing the effect on rate of reaction of surface area.
What does using finer particles mean?
This causes more ….. …. so the rate of reaction is ….
If one line showing a double quantity of chips is drawn and it goes higher on the gas released, finishing at the same time, what does this mean the extra has done?
The marble has a larger surface area
more frequent collisions, faster
The extra surface area gives a quicker reaction so more gas is evolved overall.
What reaction can be done to measure the effect of concentration on rate of reaction?
What happens in this reaction, how is this measured?
What do you do for the next repeat?
How would you label the axes on a graph of the results?
Reaction of Mg and dilute HCl
It gives of hydrogen gas which can be measured using the mas balance, as readings are taken after regular time intervals
Increase the concentration of HCl and keep the quantity of Mg AND HCl the same
Time on the x, Volume on the right
A graph shows the effect of using more concentrated acid solutions in a reaction showing the effect on rate of reaction of concentration.
A higher concentration means a …. graph, and the … finished much more ….. .
steeper
reaction
quickly
