How To Determine Which Ions Are Present In Two Unknown Solutions

10. Ba (NO3)2, barium nitrate produces pale precipitate when put in reaction with sulfuric acid.

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.

1. What was the purpose of using water as a sample in some of the tests performed in the lab? (2 points) to have a control.

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

10 microliters of the sample is then added and the assay absorption is measured at 340nm. If absorbance was above 1.5, samples were diluted.

The two most obvious formation of the precipitate were the combinations with the MgSO4. The MgSO4 and NH3 solution became very opaque and the MgSO4 and Na2CO3 turned from liquid to a full solid white substance. The Na2CO3 and CH3COOH did not have as strong of a reaction, however, the precipitates were able to be visualized with in the clear

The start of the experiment consisted of filling up four beakers with de-ionized water to 150 ml. After the beakers were filled to the appropriate amounts they were then labeled with the

deduce it’s pH number, this is done by analyzing its color, and determine if the solution is acidic

“Hard water” is defined as water with an excess content of ions such as Mg2+ and Ca2+. Hard water causes a variety of problems, among them being that hard water ions can block pipes and decrease water flow, can cause scaly deposits to form where there is water contact, and cause an increase in utility bills due to amassed scales in water heaters. In this experiment, a sample of tap water was tested in order to determine the concentration of Mg2+, and then this value was compared to a limit set by the World Health Organization. In order to carry out this task, a complexometric titration was performed in which EDTA was used as the titrant, and a solution containing the tap water sample, buffer, indicator, and a solution of MgCl2, was the analyte. It was found that the magnesium ion concentration in the tap water sample was close to 0 M, and this led to the belief that there was a flaw in experimental design. Nonetheless, the evaluation of hard water ion concentration in drinking water and tap water is very important and according to the WHO, it should always be below 500 mg/litre.

The cations in both the known and unknown samples were identified by using qualitative analysis, of which were determined to be acidic, basic, or neutral by using litmus paper. Acid-base reactions, oxidation-reduction reactions, and the formation of complex ions are often used in a systematic way for either separating ions or for determining the presence of specific ions. When white precipitate formed after adding hydroxide, aluminum ion was determined to be present in the solution. However, nickel was determined to test positive when the solution changed to a hot pink color after adding a few drops of dimethylglyoxime reagent and iron was present when the solution was a reddish brown color when sodium hydroxide was added to the mixture at the very beginning of the experiment. Qualitative analysis determines that ions will undergo specific chemical reactions with certain reagents to yield observable products to detect the presence of specific ions in an aqueous solution where precipitation reactions play a major role. The qualitative analysis of ions in a mixture must add reagents that exploit the more general properties of ions to separate major groups of ions, separate major groups into subgroups with reactions that will distinguish less general properties, and add reagents that will specifically confirm the presence of individual

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

11. It is then repeated for the solution of unknown concentration (A, B or C).

and finally detection where the figures for calculating the composition of each ion is produced1.

The main objective of this experiment is to carry out qualitative analysis to identify metal cations in unknown solution 1.

0.5% of copper sulphate solution was added by drop at a time and and the test tube was shaked continuously.