The contaminants may also stop the desired reaction from occurring entirely. The second test was the precipitation test for sulfate. Do not set a hot crucible on the bench top, because the temperature differential may cause the crucible to shatter. Gently scrape any crystals adhering to the filter paper onto the watch glass. The amount of aluminum foil, if all ions were filtered during filtration 4.
Other tests that we could perform would be to use the percent sulfate in the alum and find its mole ratio to figure out how much water is in the alum. Heat the mixture on a hot plate if any solids begin to develop in the mixture. Cool the crucible to room temperature on the triangle this takes about ten minutes. To find the formula of a hydrate, the hydrous sample is heated until all water is gone from the compound. After pouring the crystals for filtration, there was no change but specific smell was coming out.
Summary table for Week 3. The most likely source of error is that not all of the water was driven off during the heating. Remove the heat and completely cover the crucible with the lid. Most of the recycled aluminium is melted and recast into other aluminium metal products or used in the production of various aluminium compounds, the most common of which are the alums. Data and Calculations: In this lab, a beverage can is used to get aluminum sheet and then, sheet is cut into small pieces with scissor. The crystals were then allowed to dry at room temperature, and then massed.
We then measured and recording the mass after it had been heated, and after it had dried overnight. Analysis of a Hydrate: There are three parts involved in the analysis of a hydrate: determining the melting point, determining the formula, and determining the percent sulfate. Note the color of the flame. Results and Discussion The first reaction to begin the alum synthesis process is when aluminum and potassium hydroxide are combined and water and heat are added during the reaction. Also, other compounds could have similar melting temperatures.
Tawas is applied by gently rubbing the crystal in the armpits or feet while the area is damp from. Continue heating until all of the aluminium reacts. After forgoing several reactions, 4. If some water remained in the product that was assumed to be anhydrous, then when the mole ratio was calculated, it would have seemed as if the moles of water were smaller. . If water from the hot water bath spills into the beaker there will be a drasticdecrease in the yield of alum. The anhydrous alum may be disposed of in the trash or in the sink with plenty of water.
Stir the solution with your glass stirring rod and cover it with a watch glass. Some reasons for not getting a 100% may include the crystals still have moisture in them, any incorrect measurments, impurities in solutions, and the fact the crystals kept in the drawer were not. The beaker was placed on a hot plate in the fume hood. A way to prevent this type of error would be to heat the alum thoroughly, either by heating more vigorously or for a longer period of time. Aluminium is also used for making utensils.
The former is usually accomplished using elemental analysis, mass spectroscopy, X-ray crystallography or some spectroscopic method. The same was done for the other crucible. Each crucible was placed back into the beaker and into the oven for another 30 minutes. If it is dry enough to remove from the filter, the solid will not be very sticky and will have the consistency of fine sand. While it may seem a trivial exercise to identify the reactants, this is not always the case. A way to prevent this type of error is to ensure that all objects that come into contact with the alum have been thoroughly cleaned and dried first.
If the reaction becomes too vigorous, remove the beaker from the water bath until the reaction subsides. Keep the crystals from different crops and syntheses separate. The crucible was heated for 5 minutes until it was red hot. Mix thoroughly by stoppering the flask, and then inverting and shaking the flask. Because we know that the true ratio is 1:12, it can be inferred that an error was made. During the second crystallization, no more alum crystals were obtained.
The massed Al foil was cut into very small pieces and placed into a 100-mL beaker. Analysis of a Hydrate Part 1: Approximately 0. Using a 1 L plastic beaker, prepare another ice bath and place the beaker containing the reaction mixture in the ice bath. Procedure We then added sulfuric acid and gently boiled the mixture. If you do not come to laboratory prepared, you will not be able to complete the Week 2 and Week 3 exercises in the allotted time.