Aim I am trying to find out how the concentration of acid affects the rate of reaction between marble and acid. I could do this in three different ways but I have chosen to use a balance to measure the mass lost during the experiment. The other two ways I could have chosen to use are 1) time how long the Independent variables The independent variables in this experiment are: The concentration of acid Quantity of marble Volume of acid Mass of marble Surface area of marble Temperature of acid Dependant variable The variables that I am measuring from are the time taken and the mass loss of the solution as it is reacting. This will show me the rate of reaction.
Method I will now go through step by step how I will do my Investigation. "<< First I will measure out my marble into gallipot's using a balance. I have chosen to use 10 grams of marble. "<< Then I will measure out 40 ml of the required concentration of acid using a syringe and then put it in a conical flask and weigh it on a balance. I will have to add the mass of the acid and the mass of the marble together to get the starting mass of the solution because if I weigh it while the marble is in the solution it will have already started to react and therefore will be inaccurate.
"<< After I have calculated the starting mass I will add the marble to the acid and start the stopwatch. "<< Every 30 seconds I will take a reading from the balance up until 5 minutes. "<< I will repeat this with the same concentration of acid to get my second reading. "<< I will carry out this experiment for each of the concentrations of acid from 0. 5 to 4 molar doing two tests for each one. "<< When I have all of my results I will work out the average results by adding the results from the two tests and dividing by two.
To get the concentrations of acid needed I had to dilute acid with water. This is the table to show the quantity of acid to water. Concentration needed (molars) Amount of acid (ml) Amount of water (ml) 0. 5 20 ml of 1 molar acid 20 ml 1 40 ml of 1 molar acid 0 ml 1. 5 15 ml of 4 molar acid 25 ml 2 20 ml of 4 molar acid 20 ml 2. 5 25 ml of 4 molar acid 15 ml 3 30 ml of 4 molar acid 10 ml 3.
5 35 ml of 4 molar acid 5 ml 4 40 ml of 4 molar acid 0 ml Apparatus Conical flask! V to perform the reaction in Balance! V to measure the mass of the marble, starting mass and the mass loss Acid! V to react with the marble Marble! V to react with the acid Stop watch! V to time the solution as it reacts Syringe! V to measure the acid and water Safety goggles! V to protect my eyes Controls I will keep all independent variables the same apart from concentration of acid. I will also keep all the apparatus the same. Prediction I predict that there will be more mass loss from the experiment with the highest concentration of acid because chemical reactions occur when reacting particles collide with each other. Increased concentration means increased number of particles resulting in an increased number of collisions and an increased rate of reaction. Safety The following safety precautions should be taken into consideration: I will make sure that all bags are under the tables so that no one will trip over them I will also make sure that I have a clear workspace so that nothing will knock any chemicals over I will wear safety goggles at all times so that no chemicals spit out into my eyes Results.