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

Determining the atomic mass of lithium from method one. After setting up my apparatus, I went on to measure my Lithium metal

Extracts from this document...

Introduction

Safety Prior to starting this experiment, I wrote a risk assessment which covered the possible risks and hazards associated with practical and how to avoid them. I know that lithium is highly flammable and reacts vigorously with water to produce lithium hydroxide which is an irritant and can coarse serious damage if it gets into the eyes. Hydrochloric acid is also corrosive and irritant. To avoid these hazards I wore eye protection throughout the experiment. I also wore a lab coat to protect any acid from spilling on my clothes and gloves to protect my hands. Fair test * Lithium is immersed in paraffin therefore I will dry it before weighing to avoid taking a wrong weight which might affect the reliability of my final result. * I will also to set up my apparatus before putting the lithium in to the water and quickly place the bang so as to reduce the risk of loosing any gas * I will ensure that all the apparatus are rinsed with distilled water first then where possible with chemical it is to contain. This is to reduce the risk of contamination. ...read more.

Middle

When phenolphthalein indicator is added to the lithium hydroxide solution, it changes the colour into pink. In the titration there is a point where the colour will change from pink to still-grey. This is the end point and it is at this point that I took the burette's reading. My first titration (rough) was to give me a rough idea of where this point is so that I will be more careful with the rest when it nears the same volume by running the titration drop by drop. This will improve the accuracy of my results. I also repeated the titration of three times which improves the reliability of my results and read the bottom of the meniscus when taking readings and took it to the nearest 0.05cm3 for better precision and accuracy RESULTS No. of titre Start (in cm3) Finish (in cm3) Average titre (in cm3) Rough 0.00 28.85 28.85 1st 0.00 28.50 28.50 2nd 0.00 28.45 28.45 3rd 0.00 28.50 28.50 Mean titration = (28.50+28.45+28.50) � 3 = 28.48cm3 Calculating no of moles of HCl No. of moles = concentration x volume Volume of HCl = 28.48cm3 = 0.02848dm3 Concentration = 0.100dm3 ==> 0.100 � 0.02848 = 0.002848moles From here I will find the number of moles of LiOH The balanced chemical equation bellow shows the reaction between Lithium Hydroxide and Hydrochloric acid. ...read more.

Conclusion

The only thing I could have done was to ensure every thing was set up before taking out the Li and quicken the drying and measuring of it * Another problem that could have affected the reliability of my final result was the equipments. Most of the equipments I used were class B. this could have affected accuracy of the measurement reading I could avoid this by using class A equipments so that the reading is as accurate as possible. Collecting the gas in a gas syringe could also give more accurate readings. * There could be errors when reading the level of the burette and visually checking for the point at which the solution turned from pink to colourless. This fault is almost impossible to eradicate. * It was required that only 5 drops of indicator were added, this was done carefully but the sizes of each drop may differ from the other, although very minimal this could affect the final result. Adding 20 drops to the 100cm� before taking out anything would have ensured even distribution of the indicator * Another problem was weighting the lithium. As it was stored under oil for it's reactive nature ?? ?? ?? ?? 1 Zakaria Dahir ...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.

    + (7.5 x 6) = 6.925g mol-1 100 The relative atomic mass of lithium is 6.9g mol-1 Evaluation On the whole, both experiments went exceptionally well. Most of my results were as I expected and I observed extreme safety throughout the experiments because we were using a lot of glass apparatus and corrosive acid for experiment 2.

  2. DECOMPOSITON OF HYDROGEN PEROXIDE WITH HEAVY METAL CATALYSTS

    Readings should be taken every 10 seconds. 5- Record how much gas if any is collected until the syringe stops moving itself. 6- Repeat the experiment with MnO2 so three sets of results can be collected to find an average.

  1. Determination of the relative atomic mass of lithium.

    I can see that the mass (m) is over the number of moles (n). This means I have to calculate the answer by using the mass over the number of moles. So when I re - arrange the formula it will look like this: Mr = m n With the

  2. Determine the relative atomic mass of lithium.

    I would need to work out the number of moles of lithium hydroxide present in the 100 cm� of the solution from method 1. I know that in 25 cm� of lithium hydroxide there is 0.00291 mole so in 100 cm� there would be - 0.00291 x 4 = 0.01164

  1. Determination Of The Atomic mass of Lithium.

    0.004375 * 4 = 0.0175 * Use this and the original mass of lithium to calculate the relative atomic mass of lithium. Ar = Mass Moles Ar = 0.13 0.0175 Ar = 7.42857 Evaluation: The actual relative atomic mass of lithium is 6.94.

  2. Chemistry - What is the atomic mass of lithium? Method one: The first method ...

    Titration number cm� of HCl to neutralise solution 1 34.7 2 34.6 3 34.45 4 34.5 The two closest and also must accurate results where titration numbers 3 and 4 these where within 0.1ml of each other. If I take an average of these I get: Treatment of results: Evaluation:

  1. Relative atomic Mass of Lithium

    The following calculation shows how the significance of the errors is calculated in relation to comparing the measurement errors; Uncertainty (%) = Multiplied by 100 Below are all the measurement errors of all relative pieces of equipment used during the experiment.

  2. To determine the relative atomic mass of Lithium

    Oil is a viscous liquid that are generally immiscible with water. The Li can jeopardise results if care is not taken due to presence of the oil, Although the oil will not have any effect because it will not react therefore the not will affect the volume of H2 gas

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