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Introduction

GCSE Chemistry coursework: Rate of reaction between magnesium ribbon and hydrochloric acid Aim: The aim of the investigation is to find out what effect concentration of acid has on the reaction between hydrochloric acid and magnesium ribbon. Introduction: The concentration refers to the number of particles in a given volume, a more concentrated solution has more particles in the same area. This means the particles are more likely to collide with one another, thus increasing the rate of reaction. The more collisions with sufficient energy increases rate of reaction . I chose to do this particular experiment because I found it interesting and I wanted to see how much of an effect concentration would have on the rate of reaction. I also found this reaction to be good for measuring the effects of increased concentration. Key variables: The rate of reaction depends on four factors and the following are the four possible factors I could investigate: 1. Temperature: This increases the number of collisions, when the temperature is increased, the particles have more energy and move more quickly. If they are going to move quicker, they will have more collisions. 2. Concentration: This also increases the number of collisions. If the solution is more concentrated, there are more particles in a given volume. Which makes collisions more likely and therefore increasing the rate of reaction. 3. Catalyst: An enzyme is a biological catalyst. This increases the rate of reaction. This increases the rate of reaction without getting used up. ...read more.

Middle

8. When magnesium strip has dissolved completely stop the stop clock and record total time and total volume of hydrogen produced. 9. Repeat for 1.2m, 1.4m, 1.6m 1.8m and 2.0m Safety: I will wear goggles to protect eyes from HCl, in the case of it being splashed in eyes. I will wear non-porous gloves when handling HCl, to avoid contact with skin. Prediction and justification: I predict that as the concentration of hydrochloric acid increases, the time taken for the magnesium ribbon to completely dissolve will be reduced. I also predict that as the concentration doubles the rate of reaction will double, this is because there are more molecules in a given volume, in 2m hydrochloric acid there are twice as much molecules than in 1m of hydrochloric acid. The word equation for the reaction is: Magnesium(s) + Hydrochloric acid(l)�Magnesium chloride(l) + Hydrogen(g) The Symbol equation for the reaction is: Mg(s) + 2HCL (l) � MgCl2 (l) + H2 (g) In order for the magnesium and acid particles to react together they must collide with each other and this collision must have enough energy, so the two can react. If there are lots of reactions within a given minute, then there is a high reaction rate and a lot of the product is produced. If the reaction is slow, the reaction rate is low. The rate of reaction depends on how many successful collisions there are in a given unit of time. If the concentration of the acid is high, the rate of reaction will be faster than if the concentration is low this is because there are more particles in a given volume in a higher concentrated solution. ...read more.

Conclusion

My investigation could be improved if I used a gas syringe to record the volume of gas produced by the reaction. My current method was to, get 100ml-measuring cylinder and fill fully with water and also fill the trough 3/4 full. Cover 100ml-measuring cylinder with hand and tip upside down into trough without letting water escape. Add 1m concentration of dilute hydrochloric acid to conical flask. (Add 10ml� of 2m HCl and 10ml� distilled water). Get the end of delivery tube and put into trough and under 100ml-measuring cylinder. Get 2cm magnesium ribbon and add to dilute hydrochloric acid, start stop clock immediately and at the same time cover conical flask with rubber side of delivery tube. I realised that there was always a small air bubble at the top of the 100ml measuring cylinder, which could not filled with water, this may have given inaccurate readings of the amount of gas produced. Also there was a delay of up to 1 second between when the magnesium ribbon was dropped into the flask and the delivery tube being put into the flask, which meant that the first second or two of gas produced was not being transported into the 100ml measuring cylinder, which gave partly inaccurate results. If I used a gas syringe, it would have been easier and quicker to put he rubber end onto the conical flask. Further work that can be done is measuring higher concentrations to see if between 2M and 4M the rate of reaction doubles and test with different acids to see what effect the concentration has on the rate of reaction for the acids. ...read more.

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