• 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 Calcium

Extracts from this document...

Introduction

Determination of the Relative Atomic Mass of Calcium In this experiment, I will determine the relative atomic mass of calcium by two different methods. * By measuring the volume of hydrogen produced. * By titrating the lithium hydroxide produced. Method 1 * 0.10g of calcium used. * 100cm3 of distilled water used. Results Method 1 Mass of Calcium (g) Total volume of gas produced (cm3) 0.10 37 * Starting point of water in cylinder = 238cm3 * Ending point, after reaction complete, of water in cylinder= 201cm3 * (238 - 201 = 37) Deduction of 37cm3, therefore 37cm3 of hydrogen gas produced. 1 mol of gas occupies 24000 cm3 at room temperature and pressure. Ca (s) + 2H2O (l) --> Ca(OH)2 (aq) + H2 (g) * Number of moles of hydrogen = volume of hydrogen / 24000 = 37/24000 = 0.0015416 mol = 0.001542 mol (4sf) * Number of moles of calcium = 0.001542 (ratio 1:1 with hydrogen) * Relative atomic mass of calcium = Mass of calcium / Moles = 0.10 / 0.001542 = 64.85084 = 64.85 (4sf) Method 2 * 25.0cm3 of alkaline solution used. * Amount of acid used: Starting Amount of HCl used (cm3) Amount of acid used till reaction complete- Test 1 (cm3) ...read more.

Middle

If the gas syringe is used, it would give a percentage error of 1.35 % (0.5 / 37 * 100 = 1.3513). Where as the measuring cylinder gave a percentage error of 2.70 % (1 / 37 * 100 = 2.7027). This shows if the gas syringe is used it would reduce the gap for error. Another possible error is that the calcium could have been kept for so long that it might have oxidised when it was left out in the open. This would mean that less calcium would react and would have lowered the value of the gas produced. This would give a higher relative atomic mass when calculated. To prevent this, if the experiment is repeated, it can be made sure that the lid on the pot of calcium is always kept on and only taken off when it is needed. This would reduce the oxidising of the calcium. The reaction may have been stopped before it was completed. This would results in less gas being produced and this would make the relative atomic mass higher. Also there could have been a default in the equipment being used. There could have been leakage in the pipe, causing a certain amount of gas to escape into the atmosphere and not into the measuring cylinder. ...read more.

Conclusion

If too much hydrochloric acid had been let into the solution, the value recorded in the results would be higher therefore the average would come out higher and this would give a lower relative atomic mass. The weighing scale used measured to 2 decimal places. To make the results more accurate and reduce the percentage of error a weighing scale which measured to 3 decimal places could have been used. This aspect has already been discussed in the method 1 part of the evaluation. The experiment could also be carried out a higher number of times to get an more accurate average and more accurate relative atomic mass. The error with the oxidisation of the calcium could also apply to this method and has been discussed in the first part of the evaluation. In comparison method 2 is more accurate than method 1. This is because method 2 gave a relative atomic mass of 59.17 which is closer to the factual value of 40.1when compared to the value gained by method 1, 64.85. Also the accuracy can be linked to the percentage error as method one gave a higher percentage error than method two (method 1 = 61.72 %, method 2 = 49.56 %). Overall, both methods are very inaccurate (high percentage errors). But in comparison, method 2 is a better way of determining the relative atomic mass of calcium. DEV SEN 6L AS CHEMISTRY MODULAR COURSEWORK ...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 ...

    * To prevent any oil residue on the lithium, it must be ensured that the lithium is thoroughly wiped with a paper towel. * Insulating the conical flask used prior to the reaction to prevent heat loss. * Repeat the experiment more times to attain a greater number of concordant

  2. Determination of the Relative Atomic mass of Lithium

    however in this experiment we were limited by the volume of Lithium Hydroxide that was produced from the 1st experiment, this volume was 50cm3, but 10cm3 must be used as the rough titration and chances are that there will not be exactly 40cm3 of LiOH left to do another 4

  1. Determine the relative atomic mass of lithium.

    Method 1. Firstly the apparatus must be set up according to the diagram 2. Place the pipette into the pipette filler and use it to measure 25cm� of the Lithium hydroxide and pour it all into the beaker. And place the beaker under the burette.

  2. Investigation to determine the relative atomic mass of lithium

    of moles used in 100cm3 we will multiply our value by 4 = 0.003425 x 4 = 0.0137 moles = 0.0137 * So the R.A.M of Lithium = mass no.moles =0.10 0.0137 = 7.29927003 =7.3(1.d.p) We can see that both results were higher than the actual relative atomic mass of lithium (which was 6.9)

  1. The determination of the solubility of calcium hydroxide.

    Different indicators are suitable for different concentrations of strong and weak acids and alkali such as: * For a titration between a strong acid and a weak alkali = methyl orange is used as an indicator. * For a titration between a weak acid and strong alkali = phenolphthalein is used as an indicator.

  2. Determination of the relative atomic mass of magnesium.

    The lithium is kept in oil while in storage to prevent it from oxidising. When using the lithium the oil must be cleaned off to ensure that it reacts to its full potential. If the oil is not cleaned of the lithium will not produce as much hydrogen, also if

  1. How much Iron (II) in 100 grams of Spinach Oleracea?

    The solutions were only left for a few minutes to acclimatise, which could have resulted in the temperatures taken being inaccurate. Also as the Potassium Manganate (VII) (aq) was being added to the Oxalic Acid (aq) the temperature of it dropped or raised depending on what temperature it was already.

  2. The Determination of an Equilibrium Constant.

    = 0.35 mole Number of moles of CH3COOH produced = 0.35 mole According to the equation CH3COOH + C2H5OH CH3COOC2H5 + H2O The amount of C2H5OH produced equals the amount of CH3COOH produced ?Number of moles of C2H5OH at equilibrium = 1.288 + 0.35 = 1.638 mole The amount of CH3COOC2H5 (H2O)

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