Hydrochloric acid Essay Example for Free

Hydrochloric acid Essay In this investigation I am going to see how temperature affects the rate of reaction. To do this I will change the temperature at which a reaction between Sodium Thiosulphate and Hydrochloric acid is conducted. Here is a chemical equation for this reaction: Hydrochloric acid +Sodium Thiosulphatei Sodium chloride + sulphur dioxide + sulphur + water. 2HCl(aq) + Na2S2O3(aq) i 2NaCl(aq) + SO2(g) + S(s) + H2O(l). The precipitate of sulphur is what causes the solution to go cloudy. I will mix the reactants in a flask and then place the flask on a piece of paper with a black X drawn on it. I will time how long it takes for the X to disappear totally. This is how I will measure the rate of the reaction. I plan to take twelve readings, using twelve different temperatures. The range I will use will between 10 and 50 degrees. This is because under 10i and the reaction takes too long and over 50i the reaction is too quick and so reaction time plays a major part in the result and the percentage error will be greater. To carry out the investigation my dependant variable will be the temperature of the reactants as this is the one I will change. My independent variable will be the time taken for the X to disappear and this is the one I will measure. There are many other variables that will affect the reaction and therefore I will have to keep these variables constant to ensure a fair test and therefore reliable results. Firstly I will have to make sure the volume of the flask is kept constant as if the volume increases, the solution will be shallower and so the X will disappear more slowly. Also I will have to keep the volume of the solution the same as if there is a larger volume of solution; the X will disappear more quickly. The concentrations of the two reactants will also have to be kept constant. This is because if the concentration of a solution is increased, then there are more particles in the same volume of the solution and therefore there will be more collisions between particles and the rate of reaction will increase. I predict that as the temperature of the reaction increases, the rate of reaction will increase and therefore the X will disappear more quickly. I think this because, as you increase the temperature, the particles have more energy. This makes them move faster. Therefore more collisions occur between the particles and so the rate of reaction increases. Also, since the particles have more energy when they collide, the activation energy (minimum energy needed for particles to react when they collide) is more likely to be reached and therefore the particles are more likely to react when they collide. This also increases the rate of reaction. (see diagram below). I predict that the 10i C rule will apply to this reaction. This is the theory that, if you decrease the temperature of the reaction by 10i C the rate of reaction will approximately half. Therefore the time for the X to disappear will double. If this theory is true, this is the table of results and graph I expect to get. Temperature Time Rate 50i C 10s 0. 1 40i C 20s 0. 05 30i C 40s 0. 025 20i C 80s 0. 0125 10i C 160s 0. 00625 To investigate this theory I will plan to collect reliable evidence safely. I will make sure the experiment is safe by wearing safety glasses and wiping up any spillages of solutions. I will make the experiment fair by keeping the control variables mentioned before, the same. To keep the size of flask the same I will make sure I use the same flask for each reading, washing it out after every experiment. I will keep the concentrations of the reactants the same by using the same source of the solutions. I will keep the volume of solution the same by using the smallest measuring cylinder possible and making sure I avoid parallax error while measuring the solutions out. I will make sure to use 50cmi of Sodium Thiosulphate and 5cmi of Hydrochloric acid for all my tests. I will use 0. 1M Sodium Thiosulphate and 0. 5M Hydrochloric acid. I will also use two different thermometers to measure the temperature of the two different solutions. I will use a 100ml conical flask for the entire experiment. Here is an apparatus diagram of what I will use: This is how I will carry out the experiment Firstly I will measure out 50cmi of Sodium Thiosulphate in one measuring cylinder, and 5cmi of Hydrochloric acid in the other.   I will then draw a black X on a piece of paper, making sure it is smaller then the bottom of the flask I will place the Sodium Thiosulphate in the flask and the Hydrochloric acid in a boiling tube.