What are the identities of the substances found after electrolysis and heating? The identities of the substances found were Iodine, Iodide ion (I-), Triodide ion(I3-), Zinc metal and Zinc ion(Zn2+) Post Lab questions: 1. What did this experiment convincingly show about the composition of the white solid? I put that the experiment showed us the white substance was comprised of Zinc ions and iodide ions, and that the two ions and be separated back into their respective elements 2. During the electrolysis, a gray solid formed on the negative wire of the battery and the dark red solution formed at the positive wire of the batter.
The first test tube will be control, the second will be substrate and indicator dye, the third will be dilute extract, the fourth will be the same contents as the second, the fifth will be medium concentration of extract, the sixth will be the same contents as the second, and the seventh will be concentrated extract. 3) Add stock solutions to each tube using the corresponding graduated 5 ml pipette or dispensing device. 4) Adjust the spectrometer to zero absorbance at 500nm. Pour contents of test tube 1 into a cuvette. ) Make sure to keep time, read the spectrometer, and record the data.
5mL of acidified water will be measured, using a graduated cylinder, and will be transferred to the R tube, and will be immediately vigrously mixed with the reactants. Once the solution turns to an orange or red-brown color, a pipet will be used to quickly remove 30 drops of the solution, then transferred to the C tube, and the mixing will resume until the solution is close to room temperature. The solution will be filtered into the P tube, and the solution that is left in the R tube should be washed three times with 1mL of acidified water each time. The water should then be poured into the P tube, leaving the solid in the R tube. Using a test tube holder, heat the R tube over the Bunsen burner, moving the tube in a circular motion until all the water has evaporated.
The change in enthalpy relies on the concentration of the salt solution, because different concentrations will produce different enthalpies. There is an equation to determine how much of this heat energy is lost or gained when a reaction is performed. Q = c m (T1-T2) Where: q is the energy in Joules C is the heat capacity, measured in joules per gram per degree Celsius M is the mass of the solution, measured in grams J is the joules G is the grams of water T is the temperature ΔH=ΔE + PΔV = (q p +w) – w = q p Procedure: 1. Follow instructions 1-9 in Appendix A-1 to initialize the MeasureNet workstation. a.
10 mL of each solution [0.16M KI, 0.0055M (NH4)S2O8, 0.12M Na2S2O3, and water] were added to an Erlenmeyer flask along with about 0.2 g of starch and a drop of EDTA (to prevent coagulation) and mixed with a stir bar. The reaction was conducted twice for room temperature (24.5ºC), cold (1.5ºC), and warm (37.0ºC). Observations were made as the mixture changed from clear to a dark blue, almost black. The time for this color shift was recorded (in seconds). By varying the temperatures, variables A and Ea could be determined.
CHEM 3210 SEC 318 November 12, 2013 Nucleophile Substitution Reactions of Alkyl Halides Summary: Nucleophilic substitution can occur by an SN1 mechanism or an SN2 mechanism. In SN1 and SN2 reactions, the reaction rate is affected by: the nature of the halide, the nature of the solvent, the reaction temperature, the nature of the nucleophiles, and the concentration of reactants. In this experiment we will be examining reactions with NaI/acetone and AgNO3/Ethanol. We will determine the relative rates of reaction and determine whether these substances can undergo an SN2 reaction. Halides Structure BP 1-Chlorobutane 77-78°C 1-Bromobutane 100-104°C 2-Chlorobutane 68-70°C 2-Chloro-2-methylpropane 51-52°C Bromobenzene 156°C 1-Chloro-2-butene (trans) 68°C 1-Chloro-2-butene (cis) 63.5°C 1-Chloro-2-methylpropane 68-69°C 2-Bromobutane 91°C 2-Bromo-2-methylpropane 71-73°C Procedure: 1.
Rajeev Pathapati Limiting Reactant Lab Chemistry 6th Due: 2/9/12 Introduction: When a chemical reaction occurs, there is usually a limiting reactant. In a chemical reaction, the limiting reactant, also known as the limiting reagent, is the reactant that is totally consumed at the end of a chemical reaction, and is the reactant that limits the amount of product formed. This also results in excess of the other reactant(s). The reaction tested in this experiment was between a Copper (II) Chloride aqueous solution, and Aluminum metal. The purpose of the lab was to determine which reactant was the limiting reactant, and to see how much of the other reactant was used.
As a reverse DC voltage is applied across the diode, its capacitance varies. The higher the voltage, the less the capacitance. This is due to depletion layers of the diode junction, but we wont get into details here. This variable capacitor in conjunction with the stub, which is actually an inductor (coil) is the basis of our voltage controlled oscillator! As the voltage increases across D5, the frequency of oscillation increases.
Make the new dilution series. Remember to start with salt concentration where the egg first floated. (If you don't have enough solution from the original serial dilution, make some more by starting from the stock solution.) 8. As before, test the egg in each cup, starting with the lowest salt concentration.
Explain why these are referred to as Excitatory Postsynaptic Membrane Potentials (EPSPs). These are labeled as EPSPs due to the location in which these electrical impulses are generated - @ the post synapse membrane and because they depolarize the oldmembrane. 14. Opening Cl- or K+ channels on the postsynaptic membrane will generate hyperpolarizations. Explain why these are referred to as Inhibitory Postsynaptic Membrane Potentials (IPSPs).