# Investigating Factors that Affect the Rate of Reaction Between marble and Dilute Hydrochloric Acid

The local Council are concerned about the effect of acid rain on the marble statues in the local park. Investigate a factor that affects the rate of reaction between marble (calcium carbonate) and dilute hydrochloric acid. There are three main factors that affect the rate of reaction. These are: Particle size Concentration Temperature With investigating any of these, there are slight problems which make them not as reliable as they could be. With particle size, it is extremely difficult to get control of the sizes, e.g. large, small, medium. I will not be investigating this as it is very unreliable. With concentration, even though it is easy to control by measured dilution, the room temperature affects the reaction rate, and is hard to control. If the experiment needs two lessons to be completed, the room temperature is unlikely to be the same, therefore affecting the results and making it unreliable. I will not be investigating concentration either. I will be choosing to do investigate temperature. It is difficult to get fine control without water baths or thermostatic heaters, so the results will be unreliable because of this. However, I plan to tackle this problem by putting the marble and acid on the tripod as soon as the temperature we are trying to investigate is reached, and if the temperature falls I will put the Bunsen burner under the tripod again to try and reach the temperature.
Prediction -???- The collision theory is that for a reaction to occur, particles must collide with each other. An increase in the temperature is an increase in the energy of the particles, and anything that increases the energy, and therefore the frequency of the collisions, will cause an increase of the reaction rate. I predict that when I increase the temperature, the rate of reaction will increase. This is because when I increase the temperature I am giving the particles more energy, and this will increase their speed and will therefore collide more often into each other, increasing the number of successful collisions, and causing an increased rate of reaction. Apparatus For my experiment, I will need:
A Bunsen burner to heat up the acid
1g of marble chips, this is enough to get good results (a
difference between the different temperatures results), but not
too much so it takes too long to finish reacting
30cm of acid. I chose this amount because it is enough for the
marble chips to complete their reaction.
A spatula and scientific weighing scales to measure and get an
accurate amount of marble chips
A large beaker to hold the acid and marble chips on top of the
tripod. I will be using a large beaker so that the heat doesn?t
escape easily, and can get more accurate results.
Heat proof mat
Stopwatch which records time to 1/100second to get more accurate
results
Tripod
My apparatus will be set up like this: Safety
Goggles
Hair tied back
Stools tucked under desks