Experiment 2 Time | Observations | 5 minutes | Bubbled like sugar | Once salt water was added | Turned soapy white and thick | Equation: METHOD 1) Put 2 cm3 of castor oil into a 250 cm3 beaker and add 10 cm3 of 5mol.dm-3 sodium hydroxide from a measuring cylinder. (Take care when measuring this out and adding it to the beaker to avoid any drips and spills.) 2) Heat the mixture gently over a tripod and gauze, STIRRING CONSTANTLY with a glass rod (otherwise the mixture erupts). Allow to simmer (boil gently) for 5 minutes. Steady the beaker using
Experiment 8 DETERMINATION OF % COMPOSITION OF PENNIES USING REDOX AND DOUBLE DISPLACEMENT (PRECIPITATION) REACTIONS Introduction: The main purpose of the lab is to determine the percent composition of pennies using oxidation reduction and double displacement reactions and titration techniques. The quantitative determination of zinc is conducted by precipitation followed by isolation and weighing of the Zn(OH)2 precipitate (gravimetric analysis). My expected results were that 97.5% of the penny would be zinc, and 2.5% would be copper. Experimental Procedure: 1. Obtain beaker filled with 250 mL of HCl and 5 pennies.
As before, test the egg in each cup, starting with the lowest salt concentration. In which cup did the egg float first? 9. If you want, make another dilution series, with even smaller steps, to improve the precision of your estimate. 10.
NaOH solution would be in excess and thus prepare 1 M of HNO3 solution in burette, which will be used in back-titration. 4. Determine the end point of the back-titration when NaOH solution changes its color into pink. Record the results of at least three titrations. (Make a rough titration first).
The absorption spectrum is measured using a spectrophotometer and the data is graphed in Excel. The peak of the line is used to find Vmax of Fe2+. Vmax is used to find the moles of Fe2+ and ligand. The unknown n is a ratio of moles ligand divided by moles Fe2+. Results and Discussion For the first part of the experiment (Part A), five different 100 mL volumetric flasks were each filled with 1,2,3,4 and 5 mL of iron (II) solution.
6. Add 8 drops of distilled water to well D-3. 7. Add 12 drops of HCl to well D-1. 8.
Procedure: 1. Calculate how many grams of sodium bicarbonate (NaHCO3) you will need to measure out to obtain 0.025 moles. Record the quantity to measure out here: ____________________ 2. Measure out the amount of NaHCO3 you calculated using a balance and a weighing paper. Attempt to get as close to your calculated amount as possible.
Repeat steps 1-5 for trial 2. Variables and Control test: Independent Variable: Amount of each reactant poured into the test tubes Dependent Variable: Height of each solution Constant variables: Amount of time waiting for solution Data Table: Test tube # | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Trial 1 | 0.5 cm | 1.0 cm | 1.1 cm | 1.5 cm | 1.5 cm | 1.5 cm | 1.3 cm | 1.5 cm | Trial 2 | 0.5 cm | 0.7 cm | 1.0 cm | 1.0 cm | 1.3 cm | 1.7 cm | 1.9 cm | 1.5 cm | Observation/Analysis: Solution turns yellow when a separate product is added, solid of the solution leaks down to the bottom after 20 minutes. Conclusion: The group tried to find the excess or limiting for the reaction between KI and Pb. In the end the hypothesis was supported by the data. We found that little amounts of each product led to a greater height of solids.
Obtain a clean-dry test tube. Place 0.3g of the unknown substance in the test tube. Next, add 10mL of distilled water to the test tube. Mix with a stirring rod until unknown is dissolved. 2.
Procedure 2.0ml of 1-bromobutane, 2.97g of sodium benzoate, 5.0ml of water and 4 drops of Aliquat 336 were placed into a 50ml round-bottomed flask. The mixture was underwent reflux for 1 hr at around 120oC. The mixture was cooled to the room temperature. 10ml of distilled water was added into the flask to dissolve the solid. The mixture was transferred to a separating funnel.