Courseworks

Testing for ions

A body is found in the sea, but the forensic scientist is suspicious and thinks that the murder took place elsewhere and the person has been dumped in the sea. Other possibilities include being drowned in a bath or a local fresh water lake next to a copper mine.Purpose of activity.The purpose of the activity is to find out where the person was first killed by doing tests on different types of water, which she could have died from.Planning.The first thing to do is to test the water in the person’s lungs to see what ions we would get, then test the water from the place where she was found and a place where she could have got killed to see what ions we would get, after getting all of the results from the different waters we would have to match the ions we have got from the lungs with the different waters to find out what she really died from.There were 3 different types of water’s we had to test for and they were -* Seawater – Na+, K+, Ca2+, Cl-, So42-, Co32-* Lake water – Ca2+, Cu-, Cl-* Bath water – Na+, Co32-Safety points.There were a few safety points that we had to be careful with so that the experiment would go right and that no one would get hurt.1. Making sure that we wore goggles when doing the experiments.2. Making sure that we don’t get the chemicals onto us.3. Making sure that when we were using the wire loop we had to clean it after every use just in case the chemical left on the wire would not react with other chemicalsMaterials and method used.Materials used.The equipment that we used for the experiment were -1Wire loopBunsen burnerGlass tubesChemicalsMethod.There were 2 different types of tests we had to do they were -1) Testing with solutions.1. Pour approx 3cm depth of control solution into a test tube.2. Add a few drops of specified solutions.3. Make a note of any colour changes or precipitates formed.4. If a gas is produced, bubble the gas through limewater.2) Flame test.1. Clean a wire loop in a roaring Bunsen flame.2. Rinse the wire loop in hydrochloric acid.3. Dip the wire loop into the test solution or substance.4. Test the solution by placing the loop back in the roaring Bunsen flame.5. Make a note of any colour change in the flame.Results.These are the results we got after each chemical we tested.TestedForWithResultsLungsCo32LimewaterMilkyLungsCl-Silver nitrateWhite precipitateLungsNa+FlameBright yellowLakeCl-Silver nitrateWhite precipitateLakeCu2FlameGreenLakeNa+FlameBright yellowBathNa+FlameBright yellowBathCl-Silver nitrateWhite precipitateBathCo32LimewaterMilkyBathCu2FlameGreenConclusion.After we tested the woman’s lungs to find out what ions came out of the substance, we tested other related substances which was thought to be her cause of death we then tested on these substances to find out what ions came out from them and we then eliminated each substances until we got the right substance that match’s the woman’s lungs by doing this we were able to tell where she died and how she probably died.Evaluation.I think that our tests was successful because we tested the different types of water to find out that in the end we was able to tell what was the woman’s cause of death.Also that we got the right results from what we have predicted from.Strength’s and Weaknesses.Strength’sWeaknessesEach type of water gave off a different colour, which we found easy to tell what types of ions were present in that water.The wire loop was made of a type of metal, which was quite reactive, which made the tests we did a bit different to what we would have expected.Modifications.There are a few modifications that would have made the experiment even more successful like -+* Using an un-reactive wire loop like a platinum loop, which is un-reactive at all, which would have given better results to the experiment.* We could have repeated the tests a couple of times to ensure us hat we got a fair result and that we got the right result from the experimentDiscussion of vocational Implications.A forensic scienctist would carry out the tests in the same way as we did in school but they would use more reliable equipment for the tests for example they would use a mass spectrometry which is used to get readings of a sample that is put into the machine. When a sample is put into the machine by a sciectist the machine would do tests to find out what they would know what they would be looking for after the test is complete the machine would give out a reading on paper showing what ions where present in the sample.

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