My preliminary experiments showed me that it would me more practical and time saving if I just altered the temperature of the solution as changing the concentration of the solution was very time consuming. However the preliminary experiments also helped me to choose a suitable strength of solution. Aim:- To see the effects of a change in temperature on the rate of a reaction. The reaction that will be used is: Sodium Thiosulphate + Hydrochloric Acid. Na2S2O3 (aq) + 2HCl (aq) .
Predictions First of all, here are the definitions for an acid and an alkali: An acid is a substance that forms hydrogen (H+) ions when placed in water. It can also be described as a proton donor as it provides H+ ions. An alkali is a soluble base and forms hydroxyl ions (OH-) when placed in water. It can be called a proton acceptor because it will accept hydrogen (H+) ions and form H2O. A Hydrochloric acid molecule (HCl) will release one H+ ion and one Cl- ion when placed in water.
---------- Possible independent variables are temperature, amount of hydrochloric acid, concentration of Hydrochloric acid, amount or concentration of sodium thiosulphate and whether or not a catalyst is added. * My independent variable is going to be the concentration of sodium thiosulphate. * My dependant variable will be the rate of the reaction, or time taken for the reaction to take place. Watching the cross disappear as precipitation occurs and sulphur is formed as a solid will be the method used to realise the rate. * My controlled variables will be the temperature, the concentration of hydrochloric acid, the amount of sodium thiosulphate and the amount of hydrochloric acid.
Rates of Reaction Prediction (Na2 S2 O3 + 2HCL ---> 2NaCl + SO2 + S + H2O) This is the equation for Sodium Thiosulphate reacting with 2 Molar of Hydrochloric Acid. There are a number of variables in the experiment which must be controlled in order for the experiment to be a fair test. These include temperature, which must be kept constant throughout the experiment or the results would not match. The experiment will be performed at room temperature (Around 25 degrees). Another variable is volume of Hydrochloric acid, which must be kept the same as well.
The Effect of Temperature on Enzyme Activity Experiment: To investigate the effect of temperature on enzyme activity. The enzyme used will be catalyse. The enzyme catalyse: The enzyme catalyse is a biological enzyme. It is used to break down Hydrogen Peroxide, which is harmful. The reaction that occurs is: [IMAGE] Hydrogen peroxide Water + Oxygen The activity of the enzyme catalyse can therefore be measured by the amount of oxygen (in the form of froth) that is produced.
This can be be done by using an antilog in the calculation: 2.60 = -log [H3O+ ] [H3O+ ] = antilog (-pH) [H3O+ ] = 10-2.60 [H3O+ ] = 0.0025 M From a laboratory perspective, the pH of a substance could be calculated by performing a titration to find the molar concentration of the substance itself. Then, this data can be substituted into the Acid Dissociation constant expression to solve for the unknown concentration of hydronium ions in the solution. As soon as this is computed via mathematical calculations, the hydronium ion concentration can then be inserted into the expression used to calculate the pH of the substance. d.
The rate of reaction can be affected by the concentration such as A and B in the previous equation, order of reactions, and the rate constant with each species in an overall chemical reaction. As a result, the rate law must be determined experimentally. In general, in a multi-step reac... ... middle of paper ... ...eases, including temperature. It is determined from the data that the reaction is more likely to have a step wise mechanism than a concerted due to the small – ΔS and a relatively large value of ΔH from the tables. Due to some errors, it is best to perform another experiment for future protocols.
However I changed the volume of water added with intervals of 10. I predicted that as you increase the concentrations of hydrochloric acid and add it to the sodium thiosulphate the reaction will increase. By observing my table you can see that my prediction is correct as you dilute the hydrochloric acid the reaction time takes longer. I will now discuss my variables, both dependent and independent and I will also state the reasons in why some factors need or need not be changed. Variables: The independent variable is a variable that you ... ... middle of paper ... ...wasn't enough to get many of the particles to activation energy levels.
It resembles sodium thiosulphate, Na2SO4, with one less oxygen atom and one more sulphur atom. The additional sulphur atoms can be driven out by an acid. Equation [IMAGE]Na2S2O3 + 2HCl S + 2NaCl + SO2 Sodium [IMAGE]Thiosulphate + Hydrochloric acid Sulphur + sodium chloride + sulphur dioxide Variables Independent Variable - factors to be changed: The concentration of sodium thiosulphate solution will be adjusted to be tested at different molars. This is changing the ratio of sodium thiosulphate to water. Dependant variable - factor to be measured: The time it takes for the cross to be fully out of vision will be measured to test the rate in which acid reacts with thiosulphate.
PLANNING Investigating the Kinetics of the reaction between Iodide ions and Peroxodisulphate (VI) ions By the use of an Iodine clock reaction I hope to obtain the length of time taken for Iodine ions (in potassium iodide) to react fully with Peroxodisulphate ions (in potassium Peroxodisulphate). I will do three sets of experiments changing first the concentration of iodide ions, then the concentration of Peroxodisulphate ions and finally the temperature of the solution in which the reaction is taking place. From these results, I hope to draw conclusions as to the effects of these changes to the environment of the reaction on the rate and also determine the order of the reaction and the activation enthalpy. Background information The rate of a reaction is determined by a number of factors. These include: pressure, temperature, concentration of reactants, surface area of reactants, presence of a catalyst and radiation.