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

Calculating the relative atomic mass of lithium.

Extracts from this document...

Introduction

Chemistry Assessed Practical Write-up Calculating the relative atomic mass of lithium 1) Mass of Lithium (g) Volume of Hydrogen collected (cm3) 1 1.2 129 2 1.1 120 3 1.3 137 Amount of H2 collected = 129 ml Mass of Lithium with oil = 1.2g 2Li + 2H20 --> 2LiOH + H2 Vol H2 = 129 24,000 = 0.005375 moles --> 1:2 --> 0.01075 RAM = Mass Moles RFM Lithium = 0.12 0.01075 RFM Lithium = 11.16g The RFM of Li that I worked out is = 11.16g RAM Li = 6.9g Therefore the mass of oil is: 11.16 - 6.9 = 4.26g 2) Volume Lithium Hydroxide = 25.00 cm3 exactly (using a volumetric pipette) Volume HCL (0.1 molar) to neutralize Lithium Hydroxide = See graph Start (cm3) Finish (cm3) Value (cm3) 1 0.0 27.1 27.1 2 1.2 28.2 27.0 3 0.7 27.8 27.1 LiOH + HCl --> LiCl + H2O Volume HCL = 27.1 Concentration of ...read more.

Middle

Using the volume of hydrogen I was able to calculate the moles of hydrogen. I used this work out the moles of Lithium from which I could work out the mass and RAM of Lithium. The second experiment was the titration of the lithium hydroxide that was a by-product of the first experiment. By measuring the amount of hydrochloric acid (of a known molarity) I was able to work out the RAM of Lithium. The average of the two RAM's that I found is: 10.835 + 11.16 = 10.99 2 Evaluation Both the results for the RAM that I recorded are around 11g, so any errors that have occurred have obviously affected all the results. Though the second result could be affected by more errors because it has the errors of the first results, and the risk of more errors in the second experiments. ...read more.

Conclusion

The error in the amount of HCl is about 0.1cm3 because the graduations on the pipette are 0.1cm3 apart. Taking into account all these errors the results that I obtained aren't very accurate, as the results show as they are about 4g off the proper RAM of Lithium. These results could be improved by using a 100cm3 volumetric pipette to measure the distilled water. This would make the error almost negligible. You could devise a system where the Lithium could be added when the bung was already in place, therefore there would be no gas escape. You could eliminate the error in HCl by using burette with smaller graduations. The overall percentage error is: 10.99 * 100 = 159 % 6.9 This experiment has basically gone smoothly, there were no major hiccups along the way, and although my results aren't entirely accurate, at least they are consistent. I conclude that the reason for this is that the apparatus that I used was not appropriately accurate for the experiment. 1 1 ...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. Determination of the relative atomic mass of lithium.

    To improve the accuracy of my results the room temperature should be checked. Because, if the temperature is not standard, one mole of the hydrogen would not take up 24dm3, which would make the calculations inaccurate.

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

    Instances in which percentage errors come into account are highlighted and calculated below: Mass of Lithium used was measured by a balance. The value that was recorded alongside the absolute value was 0.099 � 0.001g which means using the formula mentioned above, we reach a percentage error as below to

  1. Determination of the relative atomic mass of Lithium

    Evaluation As you can see from the results looking at the rough titration, you can identify there were slight errors. The errors may have occurred in the procedure of the experiment, as first of all there were a few variables that could not be controlled such as the temperature was approximately 25 C and the pressure was standard.

  2. Determination of the Relative Atomic mass of Lithium

    Method 1 (Gas Syringe) Method 2 (Titration) Chris 10.79 05.02 Mike 11.06 09.59 Kavit 09.40 09.02 Dipen 13.60 10.50 Arjan 12.56 07.64 Raif 11.05 08.64 My Result 10.11 08.50 Matt 14.03 09.44 From these results I will calculate the class average excluding my own results: Method 1: 82.49 / 7

  1. Determine the relative atomic mass of lithium.

    + HCl(aq) LiCl(aq) + H2O(l) Method 1 : Apparatus 1 x Measuring cylinder (250cm�) 1 x Conical flask (250cm�) 1 x Rubber bung 1 x Tube 1 x Container 1 x Electronic scale 1 x Distilled water 1 x Lithium 1 x Goggles 1 x Gloves 1 x Lab coat The apparatus should be set up like this - Method 1.

  2. Determination of the relative atomic mass of lithium.

    The volume of hydrochloric acid (dm3) = 18.67cm3 1000 = 0.01867dm3 The concentration of hydrochloric acid is 0.1M The above equation can be rearranged to make the number of moles the subject: Number of moles = concentration (M) x volume (dm3) This gives: Number of moles of HCl = 0.1M x 0.01867dm3 = 1.867 x 10-3

  1. Investigation to determine the relative atomic mass of lithium

    becomes clear the approximate volume of HCl needed is recorded. Next time, this allows the HCl to be let out within 15ml of the predicted amount, and then the titration is carried out with accuracy. Fair test and accuracy > I will try to repeat my experiment within my given

  2. Determination of the relative atomic mass of Lithium.

    + 2H2O (l) 2LiOH (aq) + H2 (g) 0.09g Step 1 : Moles of lithium, Li = mass = 0.09g = 0.0129 mol RAM 7 Step 2 : Mole ratio Li : H2 2 : 1 0.0129 mol: 6.45 x 10-3 mol (0.0129 divided by 2)

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