Basic principles

All knowledge and theory in science has originated from practical observation and experimentation: this is equally true for disciplines as diverse as analysis and synthesis. Laboratory work is an essential part of all chemistry courses and often accounts for a significant proportion of the assessment marks. This book aims to provide an easy-to-use reference source dealing with basic practical techniques and information. The skills developed in practical classes will continue to be useful throughout your course and beyond, some within science and others in any career you choose.

Being prepared
*Note: You will get the most out of laboratory work if you prepare well. Do not go into a practical session assuming that everything will be provided, without any input on your part.

The main points to remember are:

• Read any handouts in advance: make sure you understand the purpose of the practical and the particular skills involved. Does the practical relate to, or expand upon, a current topic in your lectures? Is there any additional preparatory reading that will help?
• Take along appropriate textbooks, to explain aspects in the practical.
• Consider what safety hazards might be involved, and any precautions you might need to take, before you begin.
• Listen carefully to any instructions and note any important points: adjust your schedule/handout, as necessary.
• During the practical session, organize your bench space - make sure your lab book is adjacent to, but not within, your working area. You will often find it easiest to keep clean items of glassware etc. on one side of your working space, with used equipment on the other side.
• All chemical waste (solid or liquid) should be disposed of in the appropriate containers provided (consult the demonstrator or lecturerin- charge).
• Write up your work as soon as possible, and submit it on time, or you may lose marks.
• Catch up on any work you have missed as soon as possible - preferably before the next practical session.

Basic requirements

Recording practical results
An A4 loose-leaf ring binder offers flexibility, since you can insert laboratory handouts, and lined and graph paper, at appropriate points. The danger of losing one or more pages from a loose-leaf system is the main drawback. Bound books avoid this problem, although those containing alternating lined/graph or lined/blank pages tend to be wasteful - it is often better to paste sheets of graph paper into a bound book, as required.

All experimental observations and data should be recorded in a notebook in ink at the time they are made because it is easy to forget when you are busy.
A good-quality HB pencil or propelling pencil is recommended for making diagrams etc. as mistakes are easily corrected with a vinyl eraser. Buy a black, spirit-based (permanent) marker to label experimental glassware, sample tubes, etc. Fibre-tipped fine line drawing/lettering pens are useful for preparing final versions of graphs and diagrams for assessment purposes. Use a clear ruler (with an undamaged edge) for graph drawing, so that you can see data points/information below the ruler as you draw.

Calculators
These range from basic machines with no pre-programmed functions and only one memory, to sophisticated programmable minicomputers with many memories. The following may be helpful when using a calculator:

• Power sources. Choose a battery-powered machine, rather than a mainsoperated or solar-powered type. You will need one with basic mathematical/ scientific operations including powers, logarithms, roots and parentheses (brackets), together with statistical functions such as sample means and standard deviations.
• Mode of operation. Calculators fall into two distinct groups. The older system used by, for example, Hewlett Packard calculators is known as the reverse Polish notation: to calculate the sum of two numbers, the sequence is 2 [enter] 4 + and the answer 6 is displayed. The more usual method of calculating this equation is as 2 + 4 =, which is the system used by the majority of modern calculators. Most newcomers find the latter approach to be more straightforward. Spend some time finding out how a calculator operates, e.g. does it have true algebraic logic (√ then number, rather than number then √)? How does it deal with scientific notation)?
• Display. Some calculators will display an entire mathematical operation (e.g. '2 + 4 = 6'), while others simply display the last number/operation. The former type may offer advantages in tracing errors.
• Complexity. In the early stages, it is usually better to avoid the more complex machines, full of impressive-looking, but often unused preprogrammed functions - go for more memory, parentheses, or statistical functions rather than engineering or mathematical constants. Programmable calculators may be worth considering for more advanced studies. However, it is important to note that such calculators are often unacceptable for exams.
• Using calculators - take particular care when using the exponential key 'EXP' or 'EE'. Pressing dis key produces 10^something. For example if u want to enter 2 × 10^-4, the order entry is 2, EXP, -, 4 not 2, ×, 10, EXP, -, 4.

Presenting more advanced practical work
In some practical reports and in project work, you may need to use more sophisticated presentation equipment. Word processing may be essential and computer-based graphics packages can be useful. Choose easily-read fonts such as Arial or Times New Roman for project work and posters and consider the layout and content carefully. Alternatively, you could use fine line drawing pens plus dry-transfer lettering and symbols, such as those made by Letraset^®, although this approach is usually more time consuming and less flexible than computer-based systems.

To prepare overhead transparencies for oral presentations, you can use spirit-based markers and acetate sheets. An alternative approach is to print directly from a computer-based package, using a laser printer and special acetates, or directly to 35 mm slides. You can also photocopy on to special acetates. The use of Microsoft PowerPoint^® as a presentation package has become more important in recent years. It is not uncommon to find a computer and presenter available for student use.