• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3

Determination of the Relative Atomic Mass of Lithium

Extracts from this document...

Introduction

Determination of the Relative Atomic Mass of Lithium Results To determine the relative atomic mass of lithium I cut a piece of lithium, weighing 0.82g and reacted it with 100cm3 of distilled water. This reaction gives off hydrogen gas, which I collected in a 250cm3 measuring cylinder. I collected 129cm3 of hydrogen gas. To calculate the number of moles of hydrogen that I collected, assuming that 1 mole of gas occupies 24000cm3 at room temperature and pressure, I must divide the amount of gas I collected by 24000. 129 � 24000 = 0.005375 moles I can use this information to calculate the number of moles of lithium that reacted. I will multiply the number of moles of hydrogen I collected by 2 because of the 2:1 ratio of the lithium used to hydrogen given off. 0.005375 � 2 = 0.01075 moles Now, by dividing the amount of lithium I used in the reaction, which was 0.082g, by the number of moles of Lithium that reacted, 0.01075 moles, I can work out an estimate for the relative atomic mass of lithium. 0.082 � 0.01075 = 7.628 This is close to the actual relative atomic mass of Lithium but not as accurate as I had planned to get. After doing this I then titrated 25.0cm3 of the lithium hydroxide made by the reaction, with a 0.100 moldm-3 solution of hydrochloric acid. ...read more.

Middle

When Lithium reacts with water it makes Lithium Hydroxide, which is an alkali. Although it was not a very strong alkali, because of the low concentration, I was careful not to get it on my hands. To neutralise the Lithium Hydroxide in the titration, I used 0.100 moldm-3 Hydrochloric acid. This is also not very strong, but can cause irritation to the skin and eyes, so I was again, careful not to get it on my hands. In order to stop the chemicals going in my eyes or on my clothes, I wore an apron and goggles through the whole experiment. The last chemical I used was the Phenolphthalein indicator, which I used to see when the chemicals had neutralised. This is not a high hazard, but can stain my clothes so I wore the apron and made sure not to get it on my hands. Evaluation Overall I am quite pleased with my experiments, but I would have liked them to be more accurate. Before I started the experiments I rinsed out all my apparatus with distilled water to get rid of any substances that could have been in them. These are the factors which I think affected the accuracy of my experiments. Firstly, when I was doing method 1, there were a few areas where I think I lost some accuracy. ...read more.

Conclusion

I am sure that for both methods I measured out the chemicals with a high degree of accuracy, making sure that the bottom of the meniscus was on the line at eye level when measuring, It was only when collecting results from method 1 that I made mistakes. I think the most successful part of my experiment was my titration where I managed to get very accurate results. To minimise error, I should have taken much more care in method 1, when I was collecting the gas. This is where I got the inaccuracy of my results. I could have put the top on the conical flask faster to reduce the amount of gas that escaped. Also, to increase the reliability of my results I could have asked someone to check my measurements to make sure I was reading them correctly. A way of minimising errors caused by escaping gas could be to use a gas syringe instead of collecting the gas in a measuring cylinder, because there would be less error from bubbles in the measuring cylinder and the results would be much more accurate. If I were to repeat the experiment I would take much more care when carrying out the experiments and collecting the results, but overall the experiment went as well as I expected. ?? ?? ?? ?? Rob Ayres ...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

Related GCSE Aqueous Chemistry essays

1. Determination of the relative atomic mass of lithium.

the lithium before using it, although care must be taken to make sure the surface of the lithium does not oxidise. Another factor that may have caused the anomaly is error in measurement. This could be a misjudgement through human error for example; an error in misjudging the watermark in a burette or measuring cylinder could cause slight inaccuracy.

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

Ammonium Sulphate (aq). However overall these precision errors are still small and thus would not have any dramatic effect on the experiment. It would make the solutions seem slightly more or less concentrated. Procedural Errors The solutions stood in their curvet for a few minutes and in this time the

1. Determination of the relative atomic mass of lithium.

This would have affected the conditions of each experiment; therefore inaccurate results would have been produced. An improvement for this inaccuracy is to carry out both experiments on the same day, at the same time and place.

2. Determination of the relative atomic mass of lithium.

0.13 0 224 Evaluation (method 1):) In this experiment, I believe that there could have been many errors. The main sources of error in my opinion must be human and equipment error. For example a source of error is in measuring the amounts of the substances or materials.

1. Determination of the Relative Atomic Mass of Lithium

x 10-3 mol 24 Since 2 moles of Lithium produces 1 mole of Hydrogen: 2 (6.6 x 10-3) mol of Lithium = 0.09g 0.0132 mol of Lithium = 0.09g 1 mol of Lithium = 0.09g 0.132g = 6.8g Thus the Relative Atomic Mass of Lithium is 6.8g mol-1 from experiment 1.

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

= 0.099 = 6.6892 Number of moles 0.0148 So the Relative Atomic Mass of Lithium is 6.69 (to 3 significant figures). Hazard Of Chemicals: Lithium Metal: Flammable: The metal burns in air. It reacts violently with water and acids, liberating a highly flammable gas (hydrogen*).

1. Determination of the relative atomic mass of Lithium

Results 1st Attempt 2nd Attempt 3rd Attempt Weight of Lithium 0.040g 0.044g 0.042g Amount of hydrogen collected 50 cm 76 cm 78 cm Calculations 1st Attempt - 76 cm 0.00317 0.00317 X 2 =0.0063 24000 cm 0.044 6.98 0.0063 2nd Attempt - 78 cm 0.00325 0.00325 X 2 = 0.0065

2. Determination of the Relative Atomic mass of Lithium

Therefore since the Lithium and Hydrogen are in a 2 : 1 ratio, we simply multiply the moles of Hydrogen by 2. So 2 x 0.00229 mol = 0.00458 moles of Lithium. From this we can then work out the Relative Atomic Mass by using the equation : Moles = Mass / Mr.

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