This technique prevents the product to contact other reactants, and leave the heating environment which might cause side reactions. The removal of the product also helps to shift the equilibrium position of the incomplete reaction to the right hand side, and prevents backwards reaction, resulting in an increased yield of products. This experiment also introduces the idea of azeotrope. An azeotrope is a mixture of two or more pure compounds in such a ratio that its composition cannot be changed by simple distillation. This is because when an azeotrope is boiled, the resulting vapour has the same ratio of constituents as the original mixture of liquids.
Results : Yield (mass in gram) = __________________0.128 g_____________________ Melting point of pure phenyl benzoate (OC) = ___________70O______________ Melting point of your phenyl benzoate (OC) = ___________69O______________ Questions : 1. Why do we use NaOH solution to dissolve phenol rather than water in step 1 ? Because NaOH can be use to change the phenol to ion form, which can be more soluble in the aqueous
c. Prepare the solution by dissolving 38.90 grams of ZnI2 with 500 mL of water. d. 0.0125/0.25 = 0.05 L = 50 mL. This produces 0.0125 moles of ZnI2 5. Exercise 5: a. (0.125)(0.1) = 0.0125 moles of solute b. Pour 50 mL of the stock solution to get the number of moles needed.
Discussion and Conclusion In this experiment, the bromination of an alkene will be observed and a mechanism to account for the occurrence distribution of the products will be determined. In the first part of the experiment the 0.9 grams of E-stilbene will be put in a flask with 10ml of dichloromethane and then stirred to affect dissolution of the E-stilbene, since dichloromethane is a nonpolar solvent which can dissolve the nonpolar alkene. After the E-stilbene has been dissolved, 5ml of bromine in dichloromethane will be added, which will be stirred for thirty minutes until the solution is white, to ensure that the reaction has gone to completion. Bromine in dichloromethane is used because dichloromethane works as a good solvent for bromination reactions, due to the fact that it doesn’t react with bromine or most other organic molecules. The reddish color of bromine is discharged upon addition to an alkene as the bromine reacts, making this reaction a useful qualitative test for unsaturation when the reaction has gone to completion.
Let’s call this number X. Then the structural formula of BaCl2 hydrate can be written as BaCl2•XH2O. The reaction of dehydration is |BaCl2•XH2O ( BaCl2 + XH2O |(5) | According to the stoichiometry of the reaction (5) |[pic] |(6) | Where N1 is the number of moles of BaCl2 formed in the reaction (5) and N2 is the number of moles of water lost in the reaction (5). To find out N1 you need to divide the mass of BaCl2 after the reaction by its molar mass. To find out N2 you have to determine the mass of water produced in the reaction.
b) What is the molar concentration (molarity) of ethanol in the wine? Chem 131 Solution Stoichiometry and Gas Law Problems Page 1 Problem 3 As part of some research for the product Alka-Seltzer, a researcher combines 0.840g sodium bicarbonate with 100.0 mL of 0.0500 M citric acid (H3C6H5O7). a) Write the molecular, complete ionic, and net ionic equations for this reaction (assume that each molecule of citric acid is completely neutralized). b) If the dry gas that the student actually collects occupies a volume of 0.196 L at 25°C and 1.00 atm pressure, what is the percentage yield of this reaction? c) The researcher
For this particular exercise, you should be familiar with the following: • Sublimation: Many chemicals will sublime (phase change from solid state to gas state) provided the right conditions. Iodine, for example, sublimes at room temperature. A bottle of iodine will thus always have crystals forming around inside the bottle around the cap where sublimed iodine is being deposited (phase change from gas state back to solid state). Provided the proper equipment, chemicals that are being sublimed can be recovered. Decant(ing): Decanting is a way of separating a solid from a liquid.
Calculate the molarity of the original vinegar solution and its concentration in gdm-3, given that it reacts with NaOH in a 1:1 ratio. 7. 2.5 g of a sample of ethanedioic acid, H2C2O4.nH2O, was dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 15.8 cm3 were required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Given that ethanedioic acid reacts with NaOH
In the experiment a secondary alcohol (cyclohexanol) is heated with acid (phosphoric acid). A carbocation is generated by the loss of water from cyclohexanol because of the protonated alcohol. Loss of hydrogen ion from the carbocation will give the desired alkene (cyclohexene). Fractional distillation is used to separate liquids that have different boiling points that are relatively close together. By using this method of distillation a mixture is heated to a temperature at which several fractions of the compound is evaporated the distillate is then condensed and collected.
Put aspirin powder in a beaker and pipette exactly 30 cm3 of a 1 M NaOH solution onto the powder. Stir the beaker in order to dissolve aspirin completely. 3. Add 3 drops of phenolphthalein to the beaker with aspirin powder and NaOH solution. NaOH solution would be in excess and thus prepare 1 M of HNO3 solution in burette, which will be used in back-titration.