Measuring Reaction Rate Using Volume of Gas Produced

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Chemistry 12 Formal Report
Measuring Reaction Rate using Volume of Gas Produced
By John Doe
23th October 2012

An essential element of chemistry is finding reaction rates. This is because chemists need to know how long a reaction should take. In addition to needing to know the rate of a reaction at any point in time to monitor how the reaction is proceeding.

Many factors effect reaction rates, two shown above include temperature and concentration. Concentration affects the rate of reactions because the more concentrated a solution the more likely collisions between particles will be. This is simply because there are more particles present to collide with each other. When the temperature is higher, particles will have more energy. This means that more reactions will happen for two reasons, firstly more particles will come into contact with each other because they are moving around more and secondly because the reactions occur at higher speed making it more likely to succeed.

A few other factors are the surface area and if a catalyst is present. The larger the surface area the more collisions will occur because there are more places for molecules to react with each other. A catalyst affects the rate of reaction not by increasing the number of collisions, but by making more of the collisions that do occur successful.

Ordinary household bleach is an aqueous solution of sodium hypochlorite, NaClO, this contains little more than 5% NaClO by mass. Bleaching is caused by the ion. Under normal circumstances this ion breaks down slowly giving off oxygen gas and the chloride ion, .

In order to speed up this reaction a catalyst is needed. In this experiment the catalyst used was cobalt (II) nitrate solution. When this is added to the bleach a black precipitate of cobalt (III) nitrate is formed which acts as a catalyst for the decomposition of The purpose of this experiment was to determine how concentration of reactants and temperature affect the rate of the reaction between bleach and 0.01M cobalt (II) nitrate solution. In this experiment the volume of gas produced shows the rate of the reaction.


Figure 1

Firstly, all safety protocols were ensured and applied (lab apron and safety goggles). The apparatus was set up with reference to figure 1 above.
Then, the eudiometer was filled with water and inverted into the trough, which was half filled with water. It was held in a vertical position with the burette clamp attached to the stand. The rubber tubing was joined to the top of the glass tube, which goes through the stopper on the flask. The other end of the tubing was then placed into the neck of the eudiometer. 15mL of bleach solution was measured into the 25mL-graduated cylinder and poured into the Erlenmeyer flask. As followed, 5mL of 0.10M of cobalt (II) nitrate solution was measured and poured into the 10mL-graduated cylinder. Once ready, the cobalt nitrate solution was poured into the flask containing the bleach solution, and the rubber stopper was immediately slotted in. It was then mixed and stirred as well as recorded (time). It was noted that a black precipitate of cobalt (III) oxide was forming, and from then on the flask was stirred gently and constantly. This was significant to dislodge bubbles of oxygen from the surface of the Co2O3 catalyst. Another thing that was important to note was that if the swirling was stopped or reduced, the rate decreases, so therefore the amount of swirling must be kept steady and uniform throughout the runs. The total volume of oxygen that had been collected was recorded every 30 seconds until a volume of 50mL was obtained. Also, the actual elapsed time of when the 50mL mark was reached was recorded. Once the first run was successful, the following needed to be repeated the same way: the same amount of solutions must be measured into the same containers, and the procedure of applying them needed to be the same too (time recorded,...
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