Quantitative Determination of Sulphate By Gravimetric Analysis

The purpose of this lab was to determine the limiting reactant in a mixture of to soluble salts and the percent composition of each substance in a salt mixture.

In experiment A the results from the precipitation of CaC2O4 H2O from the salt mixture were obtained by weighing the items listed on Table 1 on a scale.

In this task the concentration of an unknown sample of copper sulphate using colorimetry was used to find the concentration. In this investigation copper sulphate was used which is CuSO4.5H20 as a formula. To make a standard solution which was 1M, the same clean equipment was used to make up the standard solution as used to make sodium carbonate. However there was one difference and that was that the hot distilled water was used to dissolve the copper sulphate crystals. There had to be enough hot water in order to dissolve the crystals into the beaker and then add cold distilled water to cool the solution.

Cleaning is the first step in reprocessing instruments and it is called decontamination. The cleaning process is all soiled instruments placed in the prewash ultrasonic washer for ten minutes to remove any bacterial spores for instance, blood, tissue, and bone fragments. Then the instruments are sent through a wall washer. The wall washers are designed for the final cleaning of all instruments. Once the washer is finished, it unloads in the

directly opposite of the first test tube. By doing this, the weight inside of the centrifuge was

In reference to the analysis of anions, Table 1 shows that a precipitate was formed when our unknown was combined with HNO3 and AgNO3, thus indicating the presence of a chloride ion. Because our unknown did not form a precipitate due to HCl and BaCl2, separate, effervesce, or smell, we concluded that neither sulfate, nitrate, carbonate nor

3.0g of salicylic acid was weighed then 3.0mL of acetic anhydride and 6 drops of 85% H3PO4 were added to it. The mixture was warmed over a water bath for 5 minutes while stirring. After warming, 20 drops of distilled water was slowly added. 15mL of water was added then the solution was heated until it became clear. It was allowed to cool and was placed in an ice bath until the solution becomes cloudy. Using pre-weighed filter paper, the mixture was filtered and was allowed to dry in the filter paper.

* By using the dropper and measuring cylinder, 7 ml sodium carbonate solution was added to the test tube

In this experiment, there were 6 different test tubes, each containing a different amount of phosphate concentration. Using a balance, 1 g of phosphate in a 400 mL beaker was measured and then inserted into a 100 mL graduated cylinder. 5 mL of ammonium vanadomolybdate (AVM) was added, along with deionized water until the solution reached to 25 mL. Then the solution was poured into one of the six test tubes. Another test tube contained 2 g of phosphate (phosphate was again measured using the balance) and the step described earlier was repeated until five of the six test tubes were filled, each with the same volume of 25 mL. The sixth test tube was filled with only deionized water, with 25 mL as the volume. A spectrophotometer was then used to determine the percent transmittance for each solution. The absorbance was also calculated using the equation A = -log (T). Each given amount of phosphate was converted into moles and then applied the value of .025 L for the volume to calculate the molarity of phosphate in each solution.

Heavy precipitate emerged immediately and solution turned white in color; solution then became opaque and turned light, bright blue in color.

Then pour a small amount of aspirin into the funnel allowing the filter paper to adhere, then checking that the vacuum source and tubing is secure begin to pour the remaining amount of mixture into the funnel allowing it to pass through.

The wet, crude product was placed into the 50 mL Erlenmeyer flask. Small amounts of CaCl2 were added to dry the solution. The flask was sealed and the mixture was swirled and left to settle. Once

XIII. Carefully remove the copper metal from the filter paper onto the watch glass. (with a spatula) Place a 400 ml beaker on a hot plate contained with water. Carefully place the watch glass before the water boils to dry the copper metal. (Use the tongs to handle the hot watch glass)

1) Separate the solid from the liquid in the beaker by decanting the liquid. Ask your instructor to demonstrate the correct procedure.

1. Step six in the procedure is necessary because there maybe some left over solution left over in the filter and so we use the water to get rid of that excess solution which is leftover. Step six is also important because this 5 mL of water could make the left over precipitate release excess water in it making it so that the drying process is quicker.