The first method involves reacting a known mass of lithium with a known volume of distilled water and measuring the quantity of hydrogen which is produced. I’ll do this experiment only once because I am confident with my ability of measuring accurately and any error I performed once, I would no doubt repeat it every time. I will assume throughout that 1mole of the hydrogen I produced occupies 24000cmï¿½ at R.T.PResults:From the reaction between 100cmï¿½ of distilled water and 0.10g of lithium I collected 158cmï¿½ of hydrogen.Treatment of results:I collected 158cmï¿½ of hydrogen gas. If one mole of gas occupies 24000cmï¿½ the I can find how many moles I have by usingMethod 2:This second method uses one of the products from the previous experiment and as that is an alkali a titration can determine the concentration of the solution of lithium hydroxide.
These are the results I found when I titrated 25.0ml of the unknown concentration of LiOH with 0.100moldmï¿½ of hydrochloric acid.1. This was my rough titration, I did this to find, where the titration became neutral.2. This titrated was very close but I think went too far.
3+4 where very close titrations which is really what I expected.It is easy to see from my table tat the results I have recorded do not following 3 significant figures like the rest of my results. I have done this for a deliberate reason. This section is so crucial that I think it is reasonable to get the highest degree of accuracy I can find.Titration numbercmï¿½ of HCl to neutralise solution134.7234.6334.45434.
5The 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:To review the results I obtained the values I have for the relative atomic mass of lithium are 7.58 and 7.
25. These are obviously not correct as the value found by professional scientists is 6.94 . Many contributing factors are involved in the inaccuracy of my results. In the first method, problems come from many sources, the product, hydrogen, is collected and it passes through water. Some hydrogen may well dissolve into the water. I don’t not know how much this effects the outcome but I would say very little, but still, to minimise the effect how the gas is collected has on the results a large gas syringe would be useful. Also being able to measure the quantities of my reactants to a greater degree of accuracy would help.
But in total this would have little effect. The majority of error comes from my own error and not being accurate enough with my measuring and one important factor is the fact when placing the bung the point at which the reaction is most violent, the start, some of the hydrogen wouldn’t be caught.The second experiment if done correctly and carefully is probably going to give the most reliable results. The first area for potential error is from the previous experiment. As I used the lithium hydroxide from the last experiment it is possible that I mismeasured from here and that would continue into this experiment. The burette is a very accurate and precise piece of equipment so little error would have came from there.
Error would come from the measuring of the liquids, preciseness of the equipment used and it would also depend n how accurate the indicator I used had been.I’m going to now look at the percentage error in my experiment.Method 1:I can use this value to see how drastically the percentage error can effect my results and I can see if the range of results is reasonable or not.Method 2:Both of the ranges of the answer are very large in their scope for inaccuracies, but this is reasonable a I did get similar values for each test and this is god considering the points for error and the actual complexity of the investigation.
The main thing I can pull from my quantities exploration of errors is that it is possible that by solely looking at percentage error I could have got the accepted answer to the question, “What is the atomic mass of lithium.”Hazardous substances:Lithium – Care must be taken, lithium is an highly reactive solid, to extinguish use methods to smother lithium such as limestone or dry clay. During a fire poisonous gases are produced such as lithium oxide. Breathing in lithium particles can cause much distress with shortness of breath and coughing present. Contact with the skin can cause irritation and burns.(Information used from: http://www.state.nj.
us/health/eoh/rtkweb/1119.pdf .)Lithium hydroxide – This non explosive substance is extremely corrosive and dangerous to the respiratory system and the same the he digestive system, it causes internal burns on ingestion and external burns on contact with skin.
(Information from: http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc01/icsc0913.htm.)Hydrochloric acid – Very harmful, there are severe consequence involved in the inhalation of Hydrochloric acid.
The acid causes great ad serious discomfort within the respiratory system. Inhalation can causes irritation to the trachea and lungs. Consumption as expected causes vomiting, nausea and diarrhoea.
Contact with the skin an cause burning and ulcers.