Core Practical: Investigating Rate of Reaction Flashcards
All 7 cards in this deck
What apparatus can be used to collect and measure the volume of gas produced when hydrochloric acid reacts with marble chips?
A gas syringe, or an upturned measuring cylinder (or burette) full of water over a water trough, joined to the sealed flask by a delivery tube.
Name three practical methods that can be used to follow the rate of a reaction.
Measuring the volume of gas given off; measuring the loss in mass on a balance; timing a colour change or the formation of a precipitate (cloudiness).
In an investigation of how acid concentration affects the rate of reaction between marble chips and hydrochloric acid, what are the independent, dependent and control variables?
Independent: concentration of the acid. Dependent: volume of gas collected in a fixed time. Control: mass and size of marble chips, volume of acid, temperature.
State one risk in the sodium thiosulfate and hydrochloric acid rate experiment and a suitable precaution.
Toxic sulfur dioxide gas is produced — work in a well-ventilated room or fume cupboard and wear eye protection.
What should you do with an anomalous result when drawing a line of best fit for rate results?
Ignore it — do not let it affect the line of best fit, and repeat that measurement if possible.
What are the steps in the 'disappearing cross' method for finding the rate of the reaction between sodium thiosulfate and hydrochloric acid?
e.g. the cross disappears after 40 s
- Draw a black cross on paper and stand the conical flask on top of it.
- Add the hydrochloric acid to the sodium thiosulfate solution and start the timer at once.
- Stop the timer when the cross can no longer be seen through the cloudy sulfur: time = 40 s.
In the 'disappearing cross' experiment, how does the time taken for the cross to disappear relate to the rate of reaction?
The shorter the time, the faster the rate (rate ).