Chemistry IA – Kinetic Experiments
Practice Internal Assessment
Investigating the relationship between KI concentration and its rate of reaction with H2O2, which is measured using a spectrophotometer.
Research Question
How will changing the concentration of KI affect its rate of reaction with hydrogen peroxide? Calculated as inverse of time taken for the blue-black coloration of tri-iodide ion and starch solution, measured using a spectrophotometer.
Introduction:
The rate of reaction of a chemical reaction can be affected by several factors, one which is the concentration of the reactant(s). According to the collision theory, it tells us that as the concentration of the reactant increases, there will be an increase in the amount of molecules,
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0.1M 0.05M 0.025M 0.0125M 0.00625M
Use equation C1V1 = C2V2 to calculate the amount of water needed to dilute the solution.
10ml of 0.1M KI + 10ml of deionized water = 20ml of 0.05M KI
Measuring the time for the colour change to occur
Using a pipette, add 1ml of H2O2, HCl, starch solution and 3ml of S2O3 into a cuvette. Set up the spectrophotometer and put the cuvette into the machine Data collection starts now, allow 5 seconds. Using a pipette, now add 1ml of KI into the cuvette containing the mixture. Data for this is collected for 300 seconds Repeat the steps above (1-5) three times to collect the average for the specific concentration. Repeat the steps above (1-6) using different Ki concentrations the collect the average for all the different concentrations of KI used in the experiment.
Data Collection and Processing
Qualitative Data Before any concentration of KI is added, the mixed solution is
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However, If a mistake was made by adding too much water or too much KI, the error would be carried on and therefore will have influenced the overall results greatly. There are not a lot of improvements to this, but one way is to dilute the concentrations 1 by 1 instead of going through a serial dilution although it takes a vast amount of time.
The 5 second wait before adding KI: Since there was a 5 second wait before adding the KI into the mixture of different solutions, and also that this was added manually, the prediction of 5 seconds may have varied and therefore could have minor effects on the absorbance change. Instead of allowing 5 seconds to pass before adding the solution of KI into the mixture, all of them could be added at once and data collection can start
Question 4: List the 3 errors; • Adding too many drops of NaOH at the same time would affect the results because we can’t determine the exact equivalent point when the color changed. The results won’t be accurate and that will affect all the data that are dependent on the amount of NaOH to titrate. • Other error could be the hardness to notice a color change; we always use a white paper under the flask to determine when the color changes right away. And if we don’t use the white paper it will be hard to determine the color change and the amount of NaOH that was used to titrate it. • Also other source of error could be by not rising the burette with NaOH before we fill up with it, or it maybe they were rinsing it with a lot of NaOH which could affect the data recording for NaOH amount of titration.
Coursework Equipment List • Boiling tubes (8) I will use these because this is where I will mix both the sodium carbonate and the strontium nitrate in order to form the precipitate. I need 8 because I am going to add 8 different amounts of strontium nitrate (1-8cm³) to the 8cm³of sodium carbonate. • Measuring cylinder (1) I will use this to measure the 8cm³ of sodium carbonate and the varying amounts of strontium nitrate to put into the test tubes. • Sodium Carbonate (enough to fill 8 boiling tubes with 8cm³/64cm³)
In the first part of the experiment, Part A, the standard solutions were prepared. As a whole, the experiment was conducted by four people, however, for Part A, the group was split in two to prepare the two different solutions. Calibrations curves were created for the standard solutions of both Red 40 and Blue 1. Each solution was treated with a serial 2-fold dilution to gain different concentrations of each solution.
For this I needed to first obtain deionized water. I cleaned my large graduated cylinder and got 20 + or - 2 mL of deionized water. I then added this water to the beaker that contained the mixture I created from the last step of the experiment. I also gathered 2 boiling stones and added them to the mixture of the last step. I placed the beaker on a hot plate and heated it up to 130 degrees Celsius.
Using two test tubes, label one “s” for substrate and the other “e” for enzyme. The substrate tube should contain 7 mL of distilled water, 0.3 mL of hydrogen peroxide, and 0.2 mL guaiacol and the enzyme tube should contain 6 mL of distilled water and 1.5 mL of peroxidase. Combine the materials of the substrate and enzyme tubes, mix the two using a clean transfer pipette, transfer a portion into a cuvette so that the cuvette is about half-full then cover the top of the cuvette with Parafilm and then place it in the spectrophotometer and record absorbance. Remove the cuvette and repeat recording absorbance at 1, 2, 3, and 4 minutes. Be sure to mix the cuvette and clean its surface with Kimwipes before each reading.
After 15-20 minutes, color separation became visible; red and blue were shown around the purple as well as blue/yellow around green. Solution line stopped at 60cm. Data and Observation The water/salt solution percolates faster than the alcohol/water solution. Alcohol & water solution:
This was done to get more accurate results. The first time the experiment was conducted it was tested at three different time points, at zero minutes, fifteen minutes and
To determine the rate of reaction there are many method to be used for example, measuring the mass after the product has been added and measuring the difference in mass on the duration of a digital scale. Another method, which will be used in this experiment is using a gas syringe to measure the volume of the gas which has been produced. The cylinder inside, will be pushed out to show a quantitative presentation of the volume produced by the reaction. Hypothesis
Place sodium chloride with a concentration of 9.00 mM into left side of beaker Step 4. Place deionized water into right side of beaker Step 5. Run the experiment, once the timer hits zero record your data and flush all of the contents. Step 6. Repeat steps 3-5 with urea as your molecule.
15) After each cuvette was tested, place the distilled water sample (Cuvette zero) to reset the spectrometer and to ensure that the scale is calibrated and repeat for each cuvette test. Data/Results: Tube Number Concentration Of CoCL2 (Mg/ML) CoCL2 Stock (ML) Distilled Water (ML) Spectrometry Reading at
Dependent The time taken for the bluish -black color to fade away (color of Iodine solution mix with starch solution ). The rate of enzyme reaction Minutes (min) Table 1.1 – Table shows the controlled variables in the experiment variables Units Measures of controlled variables.
Use these results to determine the product concentration, using Beer-Lambert’s Law: A= ɛCl (where A is the absorbance, ɛ is the molar absorptivity, C is the product concentration and l is the length of solution that the light passes through). Calculate the product concentrations at every minute for 10 minutes for all 7 of the test tubes using Beer-Lambert’s Law. Plot a graph of product concentration vs. time and then use the gradients of the 7 test tubes to determine the velocities of the reaction. After calculating the velocities, plot a Michaelis-Menten graph of velocity vs. substrate concentration.
DESIGN PSOW Ajit Rajendran 13H To Determine the Time Taken for a muffin paper cup to reach the ground, while Changing the Height of each experiment Introduction: In this experiment the aim is to determine the time taken for an empty muffin paper cup to reach the ground, by changing the height the empty cup is dropped from. Both variable mentioned are going to measured (height and time taken), when conducting the experiment. In order to have a fair experiment, certain factors will be kept the same throughout the experiment: the same paper cup will be used, the dimensions of the paper cup will be constant (where external factors do not affect the shape), the method in which the paper cup will be dropped.
The 250 mL beaker was rinsed well with the distilled water. The titration procedure above was repeated 2 more times with fresh potassium acid
Introduction The goal of the experiment is to examine how the rate of reaction between Hydrochloric acid and Sodium thiosulphate is affected by altering the concentrations. The concentration of Sodium thiosulfate will be altered by adding deionised water and decreasing the amount of Sodium thiosulphate. Once the Sodium thiosulphate has been tested several times. The effect of concentration on the rate of reaction can be examined in this experiment.