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

Determination of the relative atomic mass of lithium.

Extracts from this document...

Introduction

Determination of the relative atomic mass of lithium Introduction In this experiment I will determine the relative atomic mass of lithium by two different methods: * By measuring the volume of hydrogen produced * By titrating the lithium hydroxide produced Results: METHOD 1 Assume that 1 mole of gas occupies 24000cm3 at r.p.t. 2Li(s) + 2H2O(l) LiOH(aq) + H2(g) Calculating the Ar of Lithium To find the moles of Lithium (Li) we must first find the moles of Hydrogen (H2) by using the formula: Moles = volume 24000cm3 Moles = 206cm3 24000cm3 Moles = 8.583 x 10-3 Now that we can determine the moles of Lithium (Li) by using the ratio between them: Ratio = Li : H2 2 : 1 ?Moles of Lithium = 2 x (8.583 x 10-3) = 0.017166666666 Now that we know the number of moles of Lithium we can determine its relative atomic mass (Ar). ...read more.

Middle

This is because the agreed Ar for Li is 6.9 % difference (6.9 - 6.55) x 100 = 5 % 6.9 My experiment was not 100% accurate due to the following errors: Points to note: * The measuring cylinder is not very accurate because the error here can be �2cm3. A gas syringe is more accurate to measure the volume of hydrogen gas; here the error could be �1cm3. * The gas that had been collected is not at atmospheric pressure (1 atm). However 1 mole of gas can only occupy 24000cm3 at r.t.p. Errors in Method 1 (collecting gas) * A 25cm3 measuring cylinder was used to measure the volume of gas. However a measuring cylinder is only accurate to % error = 2 x 100 = 0.97 % 206 * A 100cm3 measuring cylinder was used to measure the volume of distilled water. Here the error is �1cm3. ...read more.

Conclusion

% error = 0.1 x 100 = 0.4 % 25 * The accuracy of a burette is �0.05cm3. My average titre was 41.05cm3. % error = 0.05 x 100 = 0.1 % 41.05 Overall % error for method 2 = 0.1 + 0.4 = 0.5 % Overall % error = 0.5 + 10.97 = 11.47% Improvements for Method 1 * To prevent any H2 gas escaping the apparatus below could be used: To start the reaction, the conical flask would need to be tilted so that the water goes inside the test tube. * A gas syringe is more accurate in measuring the amount of gas. The accuracy is �1cm3. * Also a gas syringe should be used to eliminate any possibility of H2 gas dissolving in the water. The apparatus below could be used for above improvements: * To make sure the pressure of the gas is at 1 atm, lower the measuring cylinder until water level, inside and outside are the same. Improvements for Method 2 * If I had more time I could've done another titration so that the average would be more accurate. ...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. Marked by a teacher

    Enthalpy of Neutralisation.

    3 star(s)

    Putting the thermometer into the calorimeter cup, I recorded the temperature for 5 minutes at 30 seconds interval while stirring. 5m of NaoH (200cm3 of 1 molar) was carefully poured into the calorimeter and I continued to read the temperature every 30 seconds using a stop clock.

  2. Determination of the relative atomic mass of lithium.

    I will put the lithium on a piece of paper and measure the weight. I will then remove the lithium n record the weight of the paper and the excess petrolatum. I will subtract this from the first weight reading to find out the weight of the lithium.

  1. Determination of the relative atomic mass of lithium.

    of the delivery tube under the cylinder, air from the tube would escape and a few small bubbles may well travel into the cylinder. This would mean that the cylinder is not full of water and in fact have a little gas in it.

  2. Determination of the Relative Atomic Mass of Lithium

    This is more accurate than the previous mean. The new standard deviation is 0.6. This shows that the data is spread much less with the exclusion of the anomalous results. However, this standard deviation is still higher than the one for experiment 1. The above observations imply that the first experiment was more accurate than the second one.

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

    Initial Reading On Burette (cm3) Difference (cm3) 1 (Preliminary) 19.5 4.2 15.3 2 34.30 19.50 14.80* 3 15.10 1.10 14.00 4 29.70 15.10 14.60 5 16.00 1.20 14.80* 6 30.65 16.00 14.65 7 44.60 30.65 13.95 8 19.85 5.05 14.80* * Concordant Results On average, 25.0 cm3 of LiOH(aq)

  2. Determination of the relative atomic mass of Lithium

    When looking at the second method I found that the best weight of lithium to use for the experiment is 0.042g as when using this it gave a relative atomic mass of 6.84. In comparison when using 0.044g of lithium it gave the relative atomic mass of 7.24.

  1. Determination of the Relative Atomic mass of Lithium

    I have also gained the results of all my classmates and so I can use their data compared to mine, and I can also use this data to show how far away I / the class were from the actual RAM of Lithium.

  2. Determine the relative atomic mass of lithium.

    When the lithium hydroxide is titrated it will be essentially neutralised with a known concentration of an acid, in this case that acid will be hydrochloric acid, this is the formula of the titration process - LiOH(aq) + HCl(aq) LiCl(aq)

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