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# Rates of reaction of agar with different HCL concentrations

Extracts from this document...

Introduction

Rates of Reaction Background Info Collision Theory Different reactions can happen at different rates. The rate of the reaction tells us how quickly a chemical reaction happens. Reactions that occur slowly have a low rate of reaction. Reactions that happen quickly have a high rate of reaction. For example, rusting is a slow reaction: it has a low rate of reaction. Burning and explosions are very fast reactions: they have a high rate of reaction. For a chemical reaction to occur, the reactant particles must collide. But collisions with too little energy do not produce a reaction. The particles must have enough energy to overcome the activation energy in order for the collision to be successful in producing a reaction. Activation energy is the energy needed to start a reaction. The rate of reaction depends on the rate of successful collisions between reactant particles. The more successful collisions there are, the faster the rate of reaction. There are two ways to find the rate of a reaction: * Measure the rate at which a reactant is used up * Measure the rate at which a product is formed The method chosen depends on the reaction being studied. Sometimes it is easier to measure the change in the amount of a reactant that has been used up; other times it is easier to measure the change in the amount of a product that has been produced. Reactions where a single species falls decomposes in some way are slightly simpler because you won't be involved in worrying about the orientation of collisions. Reactions that involve collisions between more than two species are going to be extremely uncommon. ...read more.

Middle

the reaction will take but I also found that 0m did not turn clear this is because the are no hydrochloric acid particles to collide with the sodium carbonate so the agar will not neutralize to make the agar go clear rather it will stay pink. I found that my prediction was right so as the concentration increases, the increase in the atoms colliding decrease the time it takes in which the agar neutralizes the agar and that the technique I used made my result more accurate. I will be making the following changes to my method and equipment: Firstly, I will use a collaborated pipette instead of a measuring cylinder to make my results more accurate and this will ensure that a precise amount of water is added, so this is a more accurate way of measuring solutions. Secondly, I will increase the range to see more of a change so instead of 10 results I'll do 20 results. These changes will make my result more reliable and my technique more accurate; the rest equipment will stay the same because as I found in my preliminary they were accurate with their usage. The method will also remain the same as it produced reliable results. Final experiment Predications From what I have discussed in my introduction, if the change in concentration is increased this will result in more particles in the same volume, thus there are more collisions. Due to this I think that the higher the concentration of hydrochloric acid the shorter the time it will take for the agar to go clear. Collision theory states concentration increase will lead to there being more particles of acid available for reaction with the agar/NaCO3 particles so there are more reactions therefore the agar goes clear faster. ...read more.

Conclusion

The gradient of the graph was -1.5 showing how quickly the reaction was going. Evaluation of Procedure I believe my method was fairly accurate and I had measured the size of the agar cubes and the volume of the hydrochloric acid and dilute water correctly (as it had said in my method) by going down to table level and checking if it was exactly at the right measurement and using a calibrated pipette which is an accurate piece of equipment. I had also used suitable equipment, which I had decided after my preliminary experiment to see which equipment was suitable and kept the person who was watching the agar clear the same this is to make the result reliable as different people may observe differently to each other producing varied results. Also the fact that I had measured to two decimal places and used a digital stop clock contributed to producing reliable results. I have used a wide range to identify the marginal increases within them. I could have improved by using accurate way of cutting the agar into identical pieces I would as this could also have affect my result. Finally the person watching the agar go clear cannot be a 100% accurate so a device to exactly identify when it goes clear could have improved my results this could be a light- intensity meter with a stop clock which would stop as soon as it goes clear or I could use a speed camera and go over the film on the computer and identify were it goes clear. The sharpness of the scalpel could also have influenced my results, as the scalpel could have been slightly blunt therefore making dips and peeks on the edges of the agar. The techniques I had used had made my data reliable, which also shows that the technique was accurate. ...read more.

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## Here's what a teacher thought of this essay

3 star(s)

This is a good report investigating the relationship between concentration and rate of reaction. It is written in a clear manner, but the author often repeats themselves. The method is well set out and easy to follow. Logical conclusions are drawn.

Overall, this piece of work is 3 stars out of 5.

Marked by teacher Brady Smith 10/04/2013

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