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

Determining the relative atomic mass of lithium

Extracts from this document...


Assessed practical- Determining the relative atomic mass of lithium o Hazards of chemicals used and obtained: Method 1- 2Li(s) + 2H2O(l) � 2LiOH(aq) + H2(g) Method 2- LiOH(aq) + HCl(aq) � LiCl(aq) + 2H2O(l) In method 1 hydrogen gas is produced. This is flammable and although not a lot will be produced it would be safe to keep the product away from open flames, sparks, etc. The product of the second method, lithium hydroxide, is alkaline and an irritant. When handling it care should be taken and if it is spilt all of it should be cleaned up immediately. Although not hazardous to us the lithium is very reactive and is used in small quantities. Also precaution must be taken in order to get accurate results, as with the distilled H2O that may become contaminated. In method 2 hydrochloric acid is used and although it only has a concentration of 0.1mol dm-3 care must be taken so it isn't spilt or brought into contact with skin, as it is an irritant. ...read more.


So; moles of HCl used in the titration = concentration � volume = 0.1000mol dm-3 � 36.03 dm3 1000 = 3.603�10-3 moles As 1 mole of LiOH reacts with 1 mole of HCl, [LiOH(aq) + HCl(aq) � LiCl(aq) + 2H2O(l)] then 3.603�10-3 moles of LiOH were used in the titration. Only 25cm3 of the LiOH solution at a time during the titration, so the number of moles in the 100cm3 solution from method one = 4 � 3.603�10-3 = 0.0144moles. Therefore, the relative atomic mass of lithium = moles = 0.1000g = 6.94g mol-1. 0.0144dm3 o Evaluation: Overall my results are quite accurate and in the case of method two correct, when rounded to three significant figures. In my calculations I used four significant figures in order to improve accuracy, and by using the average of three titrations (all within one decimal place of each other) ...read more.


Ideally a polarized, un-reactive solution should be used instead. Another measurement error is the resolution of the apparatus used; the scales measured to the nearest 10mgram, the burette measured to the nearest 1cm3 whilst the measuring cylinder to the nearest 2cm3. With a higher resolution method two will have more accurate results. The most significant measurement error is the amount of gas given off in method one. Aside from the procedure the measurement can be modified to reduce the error: H2 gas produced = 172cm3 � 1cm3 (as the resolution is to the nearest 2cm3). Minimum possible value: 171cm3. Relative atomic mass of lithium: 171/24000 = 7.125�10-3moles. 7.125�10-3 � 2 = 0.01425moles. 0.1/0.01425 = 7.02g mol-1(3s.f). Maximum possible value: 173cm3. Relative atomic mass of lithium: 173/24000 = 7.208�10-3moles. 7.208�10-3 � 2 = 0.0144moles. 0.1/0.0144 = 6.94g mol-1(3s.f). ROB HENDERSON ...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.

    + 2H2O(l) 2LiOH(aq) + H2(g) If a known mass of lithium is dissolved in water, the volume of hydrogen produced can be used to calculate the relative atomic mass of lithium. This will be the basic thesis for experiment 1.

  2. Determination of the relative atomic mass of lithium.

    The equipment used in school is not extremely good. If the apparatus was of a higher standard then the level of error would decrease. Another improvement could done is too stop the bung being off the flask for that period of time when we had to add the lithium.

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

    The results should have shown that as the concentration of Iron (II) Ammonium Sulphate (aq) increased the voltage being passed between the solutions would have increased. This would have created a graph showing that an increase in concentration produces an increase in the voltage produced by the Electrochemical Cell.

  2. Determine the relative atomic mass of lithium.

    So therefore the mole ratio of lithium and hydrogen is 2:1. To deduce the moles of lithium used we must multiply the number of moles of lithium collected. 0.00625 x 2 = 0.0125 Now that the mole of the lithium has been calculated, we can use this to work out the relative atomic mass of lithium.

  1. To determine the relative atomic mass of Lithium

    When the colour changes from pink to colourless I took the burette's reading. I repeated the titration of only three times because the LiOH solution I made was only 100cm3, which is only for three titration. In order to be more accurate I took the reading of the burette to the nearest 0.05cm3.

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

    the likely errors, I can state whether or not the readings were reliable. An analysis of the errors in experimental results indicates how reliable they are. It can also suggest which aspects of the experimental method could be altered to reduce the error in the final result.

  1. To find the relative atomic mass of a sample of Lithium.

    >25 cm3 Pipette. >Pipette filler. >Water bowl. >Conical flask. >Boss clamp and Stand. >White tile. >Beakers. >Small pipette. >Distilled water dispenser >250cm3 Measuring cylinder. >Delivery tube. >Phenyl Phthalein. Method 1 Carry out the method set out for the first Experiment being careful to follow the instructions carefully.

  2. Determination of the Relative Atomic Mass of Lithium

    After the effervescence stops, indicating that the reaction is over, I will record the amount of gas collected in the measuring cylinder. Experiment 2 1. I will arrange the apparatus as shown in fig. 1b 2. First, I will fill the burette with the standardised hydrochloric acid.

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