Number of moles of HCl used:
22.8 / 1000 x 0.1 = 0.00228 mol
Number of moles of LiOH:
1:1 ratio so, 0.0228
Number of moles of LiOH present in 100cm of solution:
25cm = 0.00228 x 4 = 0.00912
RAM of Li is therefore :
1/ 0.00912 x 0.08 = 8.77
Hazard concepts:
Lithium reacts violently with water to give off flammable hydrogen gas and corrosive dust. Lithium hydroxide (LiOH) is a corrosive .Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes. Acute (short-term) inhalation exposure may cause eye, nose, and respiratory tract irritation and inflammation and pulmonary oedema in humans. Acute oral exposure may cause corrosion of the mucous membranes, oesophagus, and stomach and dermal contact may produce severe burns, ulceration, and scarring in humans. Chronic (long-term) occupational exposure to hydrochloric acid has been reported to cause gastritis, chronic bronchitis, dermatitis, and photosensitization in workers. Prolonged exposure to low concentrations may also cause dental discoloration and erosion
Evaluation:
The overall accuracy of the experiment was not very high due to apparatus and methodological errors.
The main source of error procedure-wise was titrating the LiOH solution and determining when the solution became clear. Measurements of lithium metal were fairly accurate due to use of digital weighing scales, however, when using a water bath to determine amount of hydrogen released, accuracy was not superb.
Repetition of the titration allowed for more reliable results as 2 results became 0.2cm³ off each other. Calculation of a mean titre also helped accuracy.
Validity of results:
Although there were some major sources of error, I believe this experiment to be valid. Accuracy was maintained at a level sustainable in a classroom. Extraneous variables were controlled to the best of my ability.
Reliability of results:
Due to having achieved two results within 0.2cm³ of each other I would have to say my results are reliable. Consistency in methodology was sustained and this allowed for greater accuracy of results.
