Calculate the percent error in the molar mass value. Enter both values in the Data Table. Molar Mass Na2CO3 = 105.99 g/mol – this is the closest molar mass to what I calculated, so the unknown M2CO3 must be sodium carbonate. Percent Error: 93.08g/mol – 105.99 g/mol (100) = 12.18% error 105.99 g/mol DISCUSSION Review the procedure and list the possible sources of error that would cause either the molar mass of the unknown to be (a) too high or (b) too low. The goal of this lab was to discover the unknown group 1 metal (M) of the compound M2CO3 by dissolving the compound in water and adding a solution of calcium chloride, CaCl2 to the solution in order to precipitate the carbonate ions to reveal the molar mass of the unknown element, thus determining the identity of the unknown element.
This was done by taking small amounts of the unknown acid. It was then placed into capillary tubes and inserted into the Bibby Sterilin Device. Starting with a high plateau to find a quick melting point and then proceeding to find an actual melting point. The next experiment that aided in finding more characterizations of unknown #2651145-PLF13 was equivalent weight. In order to find the equivalent weight a titration of the unknown acid had to be conducted.
For the first part of the lab, the first 400mL beaker was placed on the hot plate at setting “8”. The test tube containing the Paradichlorobenzene was then placed into the hot water bath using the ring clamp until it was completely melted and its temperature reached the 65-70 °C range, which was determined using the first thermometer. The second 400mL beaker was placed on the base of the ring stand, and the test tube was then clamped over it. Once ready, the temperature of the Paradichlorobenzene sample was recorded using the thermometer and the lower half of the test tube was immersed in the water bath. Simultaneously, the timer was started, and the temperature of the substance,
CHE 326 Experiment 2 Nitration of Methyl Benzoate I. PRE-LAB (please complete before coming to lab, should be typed, 1 page limit) [pic] A. Table of Reagents (fill in all the blanks as described in the instructions). |Compound |Mol. Weight |mmol |amount |melting point |density |Ref. | | | | |(in g or mL) | | | | |methyl benzoate | | | | | | | |nitric acid | | | | | | | |sulfuric acid | | | | | | | |methanol | | | | | | | |methyl 3-nitrobenzoate | | | | | | | B. References (provide references for the information you've given in the table of reagents) C. Safety (are any of the reagents used toxic or hazardous?
Repeat the titration until there are two titres within 0.1cm3 of each other. Record results in a suitable table. Results: Rough Titre: 7.653 First Run: 6.553 Second Run: 6.453 Third Run: 6.553 Calculations: During the titration, iron(II) ions are oxidised to iron(III) ions and manganate(VII) ions are reduced to manganese(II) ions. The equation is as follows: 5Fe2+(aq) + MnO4-(aq) + 8H+(aq) ? 5Fe3+(aq) + Mn2+(aq) + 4H2O(l) The above equation shows that one mole of manganate(VII) ions reacts with 5 moles of iron(II) ions in acid solution.
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. The mixture will still be stirred for thirty minutes, regardless of the change in color; since there is a production of an intermediate, the reaction goes by an SN2 mechanism and is dictated by second order kinetics. The dissipation of color will only indicate that the bromine in solution has reacted and not necessarily that the rest of the solution has gone to completion. While this solution is being stirred, the molecules of the mixture are coming in contact and the bromination reaction is occurring. The electrons of the polarizable pi bond in the alkene E-stilbene acts as a nucleophile, a chemical species that donates an electron pair, and attacks one of the bromines in the dibromide molecule, which then causes the sigma bond to break as well.
Indirect Gravimetric Determination of a Hydrated Compound in a Mixture Morgan Dufer I. The purpose of this lab was to find the percent of BaCl2*2H2O in a sample of unknown composition by using gravimetric analysis. II. Pre-lab Questions 1. What mass of MgCO3 is contained in a 2.750g solid sample consisting of only MgCO3 and MgO if heating to decompose all the MgCO3 according to the following equation leaves a solid residue weighing 2.160g?
5.51: Which Reagent is limiting and How Much Precipitate is formed? SCH-3UI-03 David Yu Mrs. Hatton Due Date: May 5, 2012 Cut-Off Date: May 12, 2012 Purpose: To experience and use what you have learned in class about gravimetric stoichiometry by predicting and determining the mass of precipitate of two reactants and then comparing what you experience and what you calculated. Background: Avogadro’s constant is 6.02 x 1023 to find the number of entities. A mole is a useable amount of chemicals that is practical to use. The molar mass of a compound or atom is the mass of 1 mole of anything; this is relative to the atomic mass from the periodic table.
Hypothesis: Using melting points can help determine the difference in total carbon atoms and branches between two or more compounds. Materials List: 1 Spoon 1 Paper towels 3 Small rubber bands 2 Clean sheets of paper 1 Beaker, 100 mL, glass 1 Burner-fuel 1 Burner-stand 1 Goggles-Safety 1 Magnifier, dual 1 Thermometer-in-cardboard-tube 1 Capillary tubes-3/pack 1 Tetracosane Crystals - 0.2 g in Vial 1 Tetradecanol Crystals - 0.2 g in Vial Procedures: Prior to beginning the lab exercise, read the instructions carefully. Begin by setting up a derivative melting point table to collect the data accumulated during the exercise. This lab uses heated water so be sure to follow safety procedures carefully. While conducting this laboratory experiment, be sure to use minimal amounts of each substance in order to create the habit of using only the amount necessary.
Recrystallization of the Benzoic Acid Antonio Roki CHE 311L: Organic Chemistry I Section #2 September 14, 2012 Recrystallization of the Benzoic Acid Summary: The purpose of this experiment was to determine if the process of the Recrystallization is the good method of purification of the solid substance based on its different solubility values. This experiment conducted the purification of the Benzoic acid. The melting point range of the impure Benzoic acid was determined to be 86- 108 °C. Melting point was measured one more time after the process of the purification and was determined to be 111-117 °C. The melting point ranges of the impure and pure benzoic acid seemed reasonable.