A few weeks ago, I was looking for a new reaction that could be used to investigate how concentration affects reaction time. In the past, I had always used traditional reactions such as magnesium and hydrochloric acid or Alka-Seltzer and hydrochloric acid. In most cases, this was due to ambiguous and inconsistent timing methods or simply a matter of experimental error like not ensuring the magnesium stayed in the acid without floating to the top.
Each group of students will need: Ensure that there are no naked flames. The magnesium ribbon should be clean and free from obvious corrosion or oxidation. Clean if necessary by rubbing lengths of the ribbon with fine sandpaper to remove the layer of oxidation. Each experiment run will need 50 cm3.
Though low hazard, eye protection is necessary as you may get a spray as tiny bubbles burst. Ensure that all naked flames are extinguished, and that there are no other sources of ignition available to students.
Corks are too porous and will leak. The tube through the bung should be a short section of glass, and then a flexible rubber tube can be connected. But these are very expensive and are probably best used by the teacher in a demonstration.
Syringes should not be allowed to become wet, or the plungers will stick inside the barrels. Pour the acid into the cm3 conical flask. Half fill the trough or bowl with water. Continue timing until no more gas appears to be given off. Teaching notes The equation for the reaction is: In this reaction, the magnesium and acid are gradually used up.
However the acid is in excess, so it is mainly the loss of magnesium surface area becomes smaller that causes the change in the rate. If a graph of volume y-axis against time x-axis is drawn, the slope of the graph is steepest at the beginning. This shows that the reaction is fastest at the start.
As the magnesium is used up, the rate falls. This can be seen on the graph, as the slope becomes less steep and then levels out when the reaction has stopped when no more gas is produced.
The reaction is exothermic, but the dilute acid is in excess and the rise in temperature is only of the order of 3. There is some acceleration of the reaction rate due to the rise in temperature. The volume of hydrogen gas produced is measured over a few minutes, and the results are used to plot a graph.
This collection of over practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures.
This resource image was supplied by science photo library https:Investigating the reaction between manganate(VII) and ethanedioate ions Class practical Potassium manganate(VII), KMnO 4, is a . 80 Experiment Starter Sheet - Investigating the rate of reaction between sodium thiosulphate and hydrochloric acid Here is a suggested method to investigate the effect of varying the concentration.
Investigating rates of chemical reactions. In this lesson, students will investigate the factors that affect the rate of chemical reaction between hydrochloric acid and sodium thiosulphate solution.
Aim: To investigate the rate of reaction between Calcium Carbonate and Hydrochloric Acid. Just from looking at the aim of the investigation I already know that a salt would be formed because a carbonate with an acid forms a salt.
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