Required Practicals - Rates of Reaction Flashcards
What is the goal of the rates of reaction practical?
To find out how the concentration of an acid affects the rate of reaction.
What is the apparatus list for the rates of reaction practical?
-safety goggles
-100cm3 conical flask
-a single-holed rubber bung and delivery tune to fit conical flask
-water trough
-two 100cm3 measuring cylinders
-clamp stand
-stop clock
-magnesium ribbon cut into 3 cm lengths
-two different concentrations of dilute hydrochloric acid, 1.0 mol/dm3 and 1.5 mol/dm3.
What is the method for the rates of reaction practical?
-Measure 50cm3 of 1.0mol/dm3 hydrochloric acid using a measuring cylinder. Pour the acid into the 100cm3 conical flask.
-Fit the bung and delivery tube to the top of the flask
-Half fill the trough or bowl with water
-Fill the other measuring cylinder with water. Make sure it stays filled with water when you invert it into the water trough and that the delivery tube is positioned correctly.
-Add a single 3cm strip of magnesium ribbon to the flask, put the bung back into the flask as quickly as you can and start the stopclock.
-Record the volume of hydrogen gas given off in a table.
-Repeat using 1.5 mol/dm3 hydrochloric acid.
Why does the rate of reaction increase with higher concentration?
In terms of collision theory, in a more concentrated solution, particles are closer togther thus more collisions occur per unti of time, thus rate of reaction is higher.
What is a hypothesis?
A proposal that could explain a fact or an observation.
What is the equation for the disappearing cross reaction?
Sodium thiosulfate solution + hydrochloric acid –> Sulfur
What does sulfur do in the disappearing cross practical?
It makes the solution turn cloudy.
What is turbidity?
How cloudy something is
What do we do first in the disappearing cross practical?
Use a measuring cylinder to put 10cm3 of sodium thiosulfate solution into a conical flask
What do we place the conical flask with sodium thiosulfate on in the disappearing cross practical?
Onto a printed black cross
What do we add to the conical flask after placing it on top of the black cross in the disappearing cross practical?
What do we do afterwards?
10cm3 of hydrochloric acid.
Swirl the solution and start a stopwatch.
When do we stop the clock in the disappearing cross practical?
When the cross is no longer visible at all.
How do we repeat the disappearing cross practical?
By using lower concentrations of sodium thiosulfate solution each time
What should you do for each concentration of sodium thiosulfate solution?
Repeat the experiment and calculate a mean for each concentration
What do we do to anomalous results when calculating a mean?
We discard them
When is a measurement reproducible?
If it can be repeated by another person or using a different technique or equipment to get the same result.
What is the problem with the disappearing cross practical?
People have different eyesights so some people can see the cross for longer and may not get the same results
What is the reaction for the gas volume practical?
Magnesium + hydrochloric acid –> magnesium chloride + hydrogen
What are we testing for in the gas volume practical?
The amount of gas produced per unit of time
What is the first step of the gas volume practical?
Use a measuring cylinder to place 50cm3 of hydrochloric acid into a conical flask
What do we attach the conical flask to in the gas volume practical?
Attach the conical flask to a bung and delivery tube.
What do we place the delivery tube into in the gas volume practical?
What else do we place within this?
A container filled with water.
Place an upturned measuring cylinder in the water over the delivery tube.
What do we add to the hydrochloric acid to start the gas volume practical?
What do we do after?
A 3cm strip of magnesium
Start a stopwatch
Where is hydrogen gas trapped in the gas volume practical?
In the upside-down measuring cylinder
How often do we measure the volume of hydrogen gas in gas volume practical?
Every ten seconds
How do we repeat the gas volume practical?
Use different concentrations of hydrochloric acid
How does concentration affect rate of reaction?
The greater the concentration, the faster the reaction takes place.
Why are the rate of reaction practicals reproducible?
The result is the same for two different methods.
