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

Determination of Relative atomic mass of lithium

Extracts from this document...


Assessed Practical 3 Determination of Relative atomic mass of lithium Jared Ching Evaluation: In general the accuracy of the experiments was good. However with practice, the accuracy could be improved; accuracy being how close the results are to the real answer. I think I have carried pit the experiment as well as I possibly could at the time with the given conditions and time period allowed. I have gained precise results from the practical. However, looking back at the analysis section, the relative atomic mass values I found were not exactly 6.9 as presented in the periodic timetable. Method (1) gave me 8.28; a difference of 1.38 and method (2) gave me 7.37, a difference of 0.43 to the real/reference value. Therefore method (2) proved to be more accurate. Overall the results were good and came close to the real values. There were no anomalous results. Limitations: The main sources of error that I found to be evident and which were out of my control were as follows: * In method (1), due to the oil that lithium is stored in, not only ...read more.


I also found that the reacted solution sometimes returned to a slight pink colour even after turning completely colourless. Thus this caused inevitable error. Accuracy and reliability: In method (1) the procedure was very accurate; the equipment used is very accurate, however as mentioned before, the gas lost when replacing the bung caused a degree of inaccuracy. As shown by the results, with the relative atomic mass found to be +1.38 over. In method (2) not only were the results accurate but also precise. The final relative atomic mass coming out as only +0.43 over the reference value proves a high degree of accuracy. Looking at the results table, the three accurate titrations fall within 0.1cm3 and 0.3cm3 of each other, which is a very concurrent set of results. Clearly method (1) and method (2) differ in accuracy and precision. Method (1) is clearly less accurate and precise as the gas collected from the reaction of lithium and water was not exact as hydrogen was lost in the process. ...read more.


Due to the fact that the colour change and when to stop the tap is not very obvious, more indicator should be used in order to make the more subtle changes in colour more visible. The burette tap should be opened at full until there is a small change in colour, then the tap should be closed slightly so that only drops of acid are coming through, this will improve accuracy as it will be clearer when the reaction is complete, thus more concurrent results will be produced. Clearly there is also a need for a control, although it was initially thought that it was very obvious when the solution turns colourless, this practical has shown that a control would be useful to compare the colours. However the other problem of the solution returning to a slight pink colour can be eliminated by waiting for this to occur, and when it does, titrate it further opening the burette very slightly, allowing acid to be added more slowly into the solution. Carrying out titrations is a skill that develops with practice, more repetitions will lead to improved results, both in accuracy and precision. Both methods are the most accurate, considering the equipment available. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous 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 GCSE Aqueous Chemistry essays

  1. to determine the relative atomic mass of lithium. We will be doing this via ...

    The above errors in measurement and equipment can be improved by: * Following correct procedure when taking a reading off the scales by keeping the eye lined up with the bottom of the meniscus.

  2. Determination of the Relative Atomic mass of Lithium

    So the oil and or ether on the lithium could increase the weight of the lithium which again affects the results of the experiment. There was also the possibility of gas loss when doing the 1st experiment, this is because there was a certain time delay when placing the bung

  1. Determine the relative atomic mass of lithium.

    To get the mole ratio we would need to examine the formula of the reaction. The formula is as follows - 2Li(s) + 2H2O(l) 2LiOH(aq) + H2(g) As you can see 2 moles of lithium was used to produce 1 mole of hydrogen.

  2. Investigation to determine the relative atomic mass of lithium

    all familiar with is: no.moles = mass r.a.m So if we rearrange this formula we get; R.A.M = Mass No. moles = 0.10 0.014 = 7.1g As we know that the mass of the piece of lithium weighed was 0.10g and we then divided this by its number of moles to get its relative atomic mass.

  1. Determination of the relative atomic mass of Lithium

    to be beyond the actual Ar of lithium (6.9), are: * The specified amount of lithium supposed to be used was 0.10 grams. I think the fact that I received a piece of lithium that was of 0.11 grams, caused the measured relative atomic mass of lithium to increase because

  2. Determination of the relative atomic mass of lithium.

    M = the mass of the material or substance. Mr = the relative molar mass. However in using this formula I found that it may not work properly. So I need to re - arrange the formula to get it to suite my needs because I am figuring out Mr (basically the atomic mass).

  1. To determine the relative atomic mass of Lithium

    I took the measurement of the hydrogen produced and it was exactly 190cm3. The remaining substance in the conical flask is Lithium Hydroxide, which I'll be using for the next way to find the relative atomic mass of Lithium. The balanced equation below shows the reaction between Lithium and distilled water.

  2. The Determination of an Equilibrium Constant.

    dm-3 [CH3COOH] = 1.65 / 0.25 mole dm-3 [C2H5OH] = 0.3375 / 0.25 mole dm-3 ?Kc3 = [CH3COOC2H5] * [H2O] / [CH3COOH] * [C2H5OH] = (0.4465/0.25) * (5.2185/0.25) / (1.65/0.25) * (0.3375/0.25) =0.4465 * 5.2185 / 1.65 * 0.3375 = 4.18 Mixture 4: 1 * Mass of CH3COOH = 0

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