Alum is an ionic compound, which means its melting and boiling points are likely to be too high to be measured conveniently. Using the tongs, move the crucible and contents back to the triangle and repeat the heating step for 10 minutes.
This could have happened during the crystal collection by vacuum filtration. Rinse the crucible with distilled water and dry it before returning it to your drawer.
Such imprecise and maybe even inaccurate measurements could be responsible for altering the following results for figuring out the exact percentage of sulfate in the alum.
In the first trial we obtained a percent yield of Next I have to determine Analysis of alum 1 amount of water of hydration in alum crystals. I will let it cool and mass it. Each of these properties will be compared to the literature or calculated values for alum.
Gently scrape any crystals adhering to the filter paper onto the watch glass. Share your results with your classmates. Cover the container holding the crystals with a piece of paper towel, and place it in your drawer to dry. Week 2 Before doing anything else in the laboratory obtain the mass of each crop of alum to the nearest milligram three decimal places.
Set up a ring stand, ring clamp Analysis of alum 1 porcelain triangle, as your instructor will demonstrate. Cut the weighed foil into many small pieces.
When cool, weigh the filter paper and the solid BaSO4 on an analytical balance. A percent error can then be found which, if no large errors were made, should help to identify the sample. As we have discussed in class, there are rules, such as the Law of Conservation of Mass, by which chemical reactions occur, and it took chemists a long time to understand these basic rules.
To pack the alum tightly at the closed end of the capillary tube, turn the tube so the open end is up, and bounce the bottom of the tube on the desk top. If water from the hot water bath spills into the beaker there will be a drasticdecrease in the yield of alum.
Be sure to carefully read the experimental procedure and be aware that there are a number of potential hazards. If at any time you observe white smoke being given off, or smell an acrid odor, discontinue heating immediately the sulfate is being decomposed to SO2. Alum is a general name for the type of compound in which many combinations of an alkali metal and ammonium or a trivalent metal such as aluminum, iron, or chromium.
No open flames can be present in lab while the reaction between KOH and Al is taking place. You will also perform a quantitative determination to determine the percent water by mass in alum. The precipitated barium sulfate is filtered, dried, massed, and then compared to the theoretical value of sulfate in the sample.
Comment on the results of the different tests used to verify that the sample tested was alum.
The smaller the pieces the faster the reaction will go because of the increased surface area exposed to the KOH solution.
The balanced chemical equation for this oxidation-reduction reaction is The second step of the procedure is to convert the KAl OH 4 to alum by addition of sulfuric acid H2SO4 in an acid-base reaction. The crystals are heated in a water bath, and the temperature at which they melt is recorded and compared to reported values.
Weigh the cooled crucible including its cover and the contents to the nearest milligram three decimal places. Part 3 Place the precipitated barium sulfate and the filtrate in the waste containers marked for Part 3.
Stir the solution with your glass stirring rod and cover it with a watch glass. Remember that a hot crucible looks exactly the same as a cool crucible.
If the reaction slows down, replace the water in the bath with fresh hot water. While figuring out the melting point for the alum crystals, I could have not analyzed when the alum crystals started melting exactly, leading me to maybe assume it was the first temperature that my eyes noticed.
If the alum is dry, the filter paper will separate from the crystals and you can remove the filter paper. The most likely source of error is that not all of the water was driven off during the heating.
Alum is a hydrate, which means that it is a compound that has water molecules trapped within the solid.Analysis of Alum After a compound has been synthesized, tests should be carried out to verify that the compound fonned is indeed the compound desired.
There are a number of tests that can be perfonned to verify that the compound is the one desired. In Experiment 15A.
Preparation and Analysis of Alum 1. Authors: D. L. McCurdy, V. M. Pultz and J. M. McCormick* Last Update: August 21, Introduction. One of chemistry’s goals is to be able to transform any set of substances (the reactants) to another set of substances (the products) through a chemical reaction.
Analysis of a Hydrate. Part 1: Approximately g of dry alum were pulverized with a mortar and pestle, and then packed into a capillary tube to a depth of about 1 cm. A rubber band was used to fasten the capillary tube to a thermometer with the alum level with the bulb of the thermometer. Approximately g of dry alum were pulverized with a mortar and pestle, and then packed into a capillary tube to a depth of about 1 cm.
A rubber band was used to fasten the capillary tube to a thermometer with the alum level with the bulb of the thermometer. Preparation and Analysis of Alum 1. Authors: D. L. McCurdy, V.
Pultz and J. M. McCormick* Last Update: August 21, Introduction. One of chemistry’s goals is to be able to transform any set of substances (the reactants) to another set of substances (the products) through a chemical reaction.
Mar 18, · Analysis of Alum KAl (SO4)2. 12H2O Laayla Muhammad 10/31/06 /01/06 Purpose: To do several tests to determine if the resulting crystals are really alum, to use a Thiele melting point tube to determine the melting point of synthesized sample of alum and to determine the amount of water in a synthesized sample of alum and also the percent sulfate in a synthesized sample of alum.Download