• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

an experiement to test for anions and cations

Extracts from this document...


An experiment to test for anions and cations - qualitative analysis Introduction The aim of the experiment is to test an unknown substance with a variety of experimental methods, by doing this the identity of the substance will be known. The two types of different testing methods will be anions and cations. Cations are positively charged ions; this is because the atom looses an electron during a reaction, therefore having fewer electrons than protons. Anions are negatively charged ions, as the atom gains an electron during a reaction, therefore having more electrons than protons. An ion is an atom or molecule that either has gained or lost either one or more electrons, resulting in a positive or negative charge. The concept of atoms loosing or gaining electrons is known as ionic bonding. Meaning that when an atom of a single element offers electrons to atoms of another element a bond is formed. By observing any chemical changes in the experiment (for example, colour change, precipitate formation or expelling of gas), it should be easy to identify the unknown substance. A chemical change is when a new substance is produced for example the burning of magnesium metal in oxygen to produce magnesium oxide. ...read more.


2. Using a Bunsen burner the test tube was placed into a blue flame to help it dissolve, and was then allowed to cool. 3. A clean test tube was taken and 1/3 of the solution was added to it, along with 5 drops of dilute sodium hydroxide. 4. No precipitate was formed, so the test tube was placed back into the Bunsen flame, with a piece of moist litmus paper placed over the top of the tube (ensuring that it didn't touch) 5. The paper had no change and remained red. 6. A flame test was then done using nichrome wire and a small sample of the solid. 7. The flame turned a yellow/orange colour and was identified as sodium. Testing for anions (Substance J) 1. A small spatula of substance J was added to a test tube, along with 2 dropfulls of dilute hydrochloric acid. 2. Using a Bunsen burner the test tube was placed into a blue flame and warmed gently. 3. No gas was given off, so three drops of barium chloride was added to the test tube. 4. A white precipitate had formed, indicating that it was a sulphate. ...read more.


Evaluation If the experiment was to be repeated again I would carry out further practise tests when testing for nitrate. As when I previously tested for this substance, I didn't have the technique right and didn't know what the end result would look like. When using the flame test for testing cations, it was difficult to note any colour change in the flame, to identify the unknown substance; this was because there wasn't enough of the unknown substance on the nichrome wire. A change that I would implement if the experiment was to be carried out again, would be for a spatula type/small spoon, with a wooden or glass handle (to prevent any burns) to be used with a small amount of the unknown substance on the end, that way, it would be much clearer to detect a colour change when using the flame test method. When testing for anions, it was difficult to identify whether the unknown substance was giving off a gas or was dissolving. Again, this technique would need to be practised several times, in order to be clear on the end result, and to ensure that the experiment ran smoothly. Reference/research: http://library.thinkquest.org/19957/matter/atomionmolecbody.html (viewed 26/01/09) http://en.wikipedia.org/wiki/Ion (viewed 26/01/09) http://chemistry.about.com/ (viewed 26/01/09) http://dictionary.com (viewed 26/01/09) ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Inorganic Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Inorganic Chemistry essays

  1. Peer reviewed

    Determining the concentration of acid in a given solution

    5 star(s)

    I rinsed the conical flasks thoroughly with distilled water between each titration to ensure that there was no excess sodium carbonate or sulfuric acid in the conical flask which could react with any new sodium carbonate. If I went over the endpoint and I tipped out the solution, but there

  2. Peer reviewed

    Deducing the quantity of acid in a solution

    5 star(s)

    The indicator is used so we are able to see a difference of colour when the endpoint is reached and therefore the reaction has occurred. The endpoint must look like a change in colour from yellow to red. Swirling the flask all the time, we deliver 1cm3 of H2SO4 at

  1. effects Concentration and Temperature on the Rate of Reaction

    Time Take For the Mixture to Turn Colourless (seconds) Repeat 1 Repeat 2 Repeat 3 Repeat 4 Repeat 5 Average Reaction Rate (seconds-1) 0.9 36.5 36.1 36.9 36.7 36.4 36.52 0.0274 0.7 54.3 54.5 53.9 54.2 54.1 54.20 0.0185 The result in my table highlighted both in bold and by an asterisk is clearly an anomaly.

  2. Aim To study the effect of concentration of iodide ion ...

    Uncertainty due to pipette = � ?"?# x 100 = � 0.20% ?"?? Uncertainty due to micropipette = � ?"??3 x 100 = � 0.30% "??? 6 Concentration, MKI / Uncert. in MKI, Uncert. in MKI, mol dm-3 ?MKI (mol dm-3)

  1. Finding Out how much Acid there is in a Solution

    My final value for concentration was 9.47x10-2 mol dm-3, and 1.06% of this is 1.00X10-3, so therefore the final value for my concentration can be written as 9.47x10-2 � 1.00x10-3 mol dm-3. Overall greatest sources of errors Looking at the sources of error, the possibility of having an incorrect end

  2. Flame Test Experiment

    This would stop fires form starting. If you have forgotten to take out the match and it starts a fire, then you would need to alert the teacher and students and quickly use the fire blanket to take out the fire. If the fire gets big and out of control then you need to press the fire alarm button and evacuate the building.

  1. The aim of this investigation is to analyse what cations and anions are present ...

    level Wash eyes thoroughly with clean water Barium chloride Toxic Skin contact Inhalation Always keep a lab coat on High risk level If contact with skin wash with clean water immediately Lithium Chloride irritant Harmful if swallowed Wear gloves and proactive clothing Low risk If inhaled get medical help as

  2. Anion Test- Testing for negative ions in solutions.. Applied science unit 3 (AQA)

    Putting the pipette down after use could reduce the risk level. If you accidently squirt some chemical on a student or yourself then you should first wash it off and then go seek medical advice form first aid. Medium/low because many people put the pipette down straight after use which makes the risk level medium/low.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work