The objective of the Bromocresol Green Equilibrium System Lab was to determine if the equilibrium constant, K, was a true constant at constant temperature. To determine this, the value of the constant was found at different concentrations of HIn, HIn-, and at varying pH, which was used to determine the concentration of H+. K was found using the equation K= [HIn]/([In-][H+]). In order to be a true constant, none of the values of K found should differ from the average by more than two standard deviations. The values of K for solutions 1-5 and U were 4.39E4, 4.53E4, 4.23E4, 4.70E4, 6.35E4, and 4.03E4 respectively. The average K for the lab was found to be 4.71E4 and the standard deviation was 8.302E3. The range then that all experimental values of K must fall under is 3.05E4 to 6.37E4. All experimental values of K for this trial fell within the range. Therefore, K can be determined a true constant. The pH of the solution does not affect the value of the equilibrium constant, K. K is a ratio of the concentrations of the products and the reactants. A change in pH is simply due to a change in the concentration of Hydrogen ions and hydroxide ions. A change in concentration merely causes a shift in equilibrium towards either the products or reactants. It does not however change the value of the equilibrium constant at constant temperature …show more content…
Because of this, the experiment was done at constant temperature. If solutions 1-5 had been done at different temperatures, there would not have been a way to determine the effect of the change in temperature on the magnitude of the equilibrium constant. In order to be able to determine the magnitude, the original K value would first need to be determined. Once determined and both temperatures were measured, an experiment could be done to determine the K of the second
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.
This experiment had water and the amount as a control as well as the size of the metal were also kept same. the This was why the experiment was repeated multiple times on different days. A standard deviation was found for each element when calorimeter constant and specific heat were calculated. Tuesday was the day with the least amount of deviation which meant it was the day with the most precise when calorimeter constants were compared (Table 1).
This aqueous solution was then heated until all the dichloromethane evaporated off. An error could have occurred at this point in the experiment if the hot plate was too hot. If the hot plate was set above the boiling point of the ketone, the ketone could have evaporated of along with the dichloromethane. This would result in a lower percent yield of the ketone. To prevent this from happening, the hot plate should not exceed 130˚C, so no matter what ketone was isolated, it would not evaporated off.
The color spectrum ranges from blue to yellow, which means green is equilibrium. Photosynthesis takes in carbon dioxide which makes the solution less acidic and the color blue. Cellular respiration does the opposite by releasing CO2 from the broken down glucose. Therefore, the BTB solution turns from blue to yellow.
Through this test, we are able to say that the results are statistically significant [temperature (X2=100.01, df=3), pH(X2=19.91, df=3), and light (X2=109.10, df=3)] - see Table 1, 2,
The goal of the experiment is to synthesize a bromohexane compound from 1-hexene and HBr(aq) under reflux conditions and use the silver nitrate and sodium iodide tests to determine if the product is a primary or secondary hydrocarbon. The heterogeneous reaction mixture contains 1-hexene, 48% HBr(aq), and tetrabutylammonium bromide and was heated to under reflux conditions. Heating under reflux means that the reaction mixture is heated at its boiling point so that the reaction can proceed at a faster rate. The attached reflux condenser allows volatile substances to return to the reaction flask so that no material is lost. Since alkenes are immiscible with concentrated HBr, tetrabutylammonium bromide is used as a phase-transfer catalyst.
Using the equation m = ΔTf/Kf , the molality of the unknown solution was found. Then, moles of unknown were calculated, which was used to calculate the average molar mass of unknown. Theory: After the experiment was completed, the data
Materials: The materials that I will be utilizing during these experimentations are three to four ice cubes, one cup for measuring, six unblemished cups, one stopwatch, one hot water source, three tablets of Alka-Seltzer, one thermometer that measures from negative
The topic of research is, “how fast does an Alka-Seltzer tablet make gas?”. In the experiment, the scientists will be measuring the chemical reaction rates that occur, when 1 Alka-Seltzer tablet is placed in a specific temperature of water. The independent variable during the experiment will be the temperature of the water (degrees Celsius). The dependent variable during the experiment will be, the rate in which gas is produced (in seconds). The constants of the experiment, will be the amount of water used and the Alka Selter compound.
There are multiple points both at 43°C and at 72°C which indicates that liquid was collected at these temperatures. Based on this information, it would appear that two different liquids were present in solution and that one liquid has a boiling point of approximately 43°C and that the other has a boiling point of approximately 72°C. The literature value boiling point for DCM in is reported to be about 40°C and it is about 80°C for cyclohexane. Based on the graph, DCM was collected from 4 ml to 22 ml, thus 18 ml of DCM was collected.
Acids are proton donors in chemical reactions which increase the number of hydrogen ions in a solution while bases are proton acceptors in reactions which reduce the number of hydrogen ions in a solution. Therefore, an acidic solution has more hydrogen ions than a basic solution; and basic solution has more hydroxide ions than an acidic solution. Acid substances taste sour. They have a pH lower than 7 and turns blue litmus paper into red. Meanwhile, bases are slippery and taste bitter.
Practical I: Acid-base equilibrium & pH of solutions Aims/Objectives: 1. To determine the pH range where the indicator changes colour. 2. To identify the suitable indicators for different titrations. 3.
Introduction Buffer is a solution that resists a change in pH when bases or acid are added. Solutions that are acidic contain high concentrations of hydrogen ions (H+) and have pH values less than seven. Buffer usually consist of a weak acid, and its conjugate base or a weak base and its conjugate acid. The function of buffer is to resist the changes in hydrogen ion concentration as a result of internal and environmental factor. This buffer experiment is important so that we relies the important of buffer in our life.
The 250 mL beaker was rinsed well with the distilled water. The titration procedure above was repeated 2 more times with fresh potassium acid
Synopsis This experiment is the determination of Calcium Carbonate (CaCO3) content in toothpaste with the use of back titration while demonstrating quantitative transfer of solids and liquids. A accurately weighed quantity of toothpaste was dissolved in excess volumes of HCl. This solution is then titrated with NaOH to find the volume of the excess HCl. The volume of HCl reacted, which is found by substracting the volume of given HCl with the volume of excess HCl reacted, can be further manipulated with mole fractions to find the mass of CaCO3 and thus the CaCO3 content in toothpastes.