Welcome to the Lab

Welcome to the Laboratory

My apologies, diagrams were lost when I moved this page from my wiki. I will restore them when I have time, and write the SLOs for the unit.

This page covers the section of this unit concerned with working scientifically, laboratory safety, laboratory equipment and its use.


Laboratory Rules

Rules are needed in the laboratory to keep everyone safe and to make sure that equipment is not damaged.

Some of the rules we use at Sacred Heart are:


Safety Rules

  • Always wear safety glasses when working with glass, chemicals or heat.
  • Long hair must be tied up during practical work
  • No schoolbags in the laboratory - place them in the cubbyholes at the entrance
  • Do not touch anything in the room on the side benches, unless instructed to by the teacher
  • Do not sit on the benches or side benches
  • Ensure you know the location of the emergency stop for GAS, WATER & ELECTRICITY (usually behind the teachers desk)
  • Always push your chair in when not using it
  • Report any breakages immediately
  • Do not bring food or drink in to the laboratory
  • Ask for help if you do not understand
  • take note of the location of the following safety features in the lab: Emergency Exit, Emergency Eye Wash; Fire Extinguisher, first aid kit and fire blanket.
  • ensure you are aware of any out of bounds areas


Courtesy Rules

  • Be on time to science
  • Do not talk when the teacher talks
  • Remain in seats during the science lesson unless instructed by your teacher
  • Bring all equipment with you to your lesson


Laboratory Equipment


The Bunsen Burner

Bunsen Burners are a common piece of heating equipment in a laboratory. They were invented by Michael Faraday but improved by Robert Bunsen.

A Bunsen Burner (often shortened to 'burner' in the lab) uses gas and premixes it with air so it can burn with a clean, sootless flame. Most burners have the ability to reduce the air supply so that the burner burns with a yellow flame which is easy to see but not used for heating because it leaves soot marks on the equipment. The parts of the Bunsen Burner are shown in the diagram below:



Lighting and using a Bunsen Burner


  1. ensure you have a heat proof mat on the bench
  2. connect the burner to the gas tap
  3. adjust the collar until the airhole is closed
  4. light your match or lighter and hold at the top of the burner
  5. turn on the gas
  6. withdraw the match or lighter when the burner shows a flame and adjust the flame height with tap if needed


Note that if you reverse steps 4 and 5 you run the risk of getting a mass of gas lighting in your face, which could be dangerous. For this reason you should always light the match before turning the gas on.

The flame at this point should be a yellow safety flame. The burner should be on a safety flame when it is not actually being used to heat something; this is because the heating flame is hard to see and a student might not notice and receive a burn by reaching through it,

  • Note: matches must be extinguished and should be disposed of in the bin at the end of the lesson; it can be a good idea to wet them to ensure there is no possibility of starting a fire in the rubbish
  • if your teacher uses lighters, these should be sat at the back of the bench when not in use (they are not toys and should not be used except to light burners)

When you are ready to heat with the burner, adjust it to a quiet blue flame by opening the airhole. If you open it too far, the burner will start to make a soft 'roaring' noise. This is caused by the burner going out and relighting several times a second, and happens just before the flame goes out altogether. A softly roaring flame is a bit hotter than a quiet flame and can be used for heating, but can go out very easily.


The yellow colour of the safety flame is caused by glowing particles of soot. This is why the safety flame leaves soot over equipment if you use it to heat. The hot soit particles normally burn away leaving no smoke, but if they touch cold glass they can't burn and remain behind.



Other lab equipment

Some other common lab equipment follows. Also given is a diagram of you you would draw it on paper. Below are both photos and diagrams of as beaker and tripod:



Two dimensional diagrams are simple pictures of the gear we use. You can see that the 2D beaker looks like it was sliced in half top to bottom. The 2D tripod shows only two of the 3 legs, because the other one is 'behind'/.


In this way, we can draw a diagram of apparatus which is used together. Below is shown a photo then a 2D drawing of a beaker, sitting on a tripod with gauze on a safety mat:


The simplified 2D drawing has the gauze and the burner omitted. In the exam it is OK to draw the simplified version but the parts you have shown must be labelled.


Measuring cylinder

These are for accurately measuring out small volumes of liquid. They are available in several sizes. The size you use should be close to the volume you are measuring e.g. you would use a 10 mL cylinder to measure 8 mL, not a 100 mL one. This is because the smallest cylinder that measures a volume is the most accurate:


When you use the measuring cylinder the top of the water makes a downward curve, called the meniscus. The measurement is taken from the lowest point of the meniscus, with your eye level with the water:



The water level in the example above is 23.5 mL (assuming that millilitresis the unit)

Volume is given in millilitres (mL) or cubic centimetres (cm3 or cc). Both of these units are the same size i.e. 10 mL = 10 cc. One thousand mL is a litre, and 1000 litres is a cubic metre (m3). Cubic metres are the SI metric unit for volume but mL are more commonly used in the lab.

Note the mL is written with a lowercase m to start with and an uppercase L following. It is important you get into the habit of writing the units exactly.


Mass is measured with a balance, such as a triple beam balance. This is a type of balance that is very accurate without requiring electricity or digital processing:




In a triple beam balance the mass on the pan is used to balance the weights on the three arms.

Each of the back two arms balances exactly the stated mass when it is in the 'slot' where it clicks into place.


Example: if you put a rock (actual mass 183.2 grams) on the pan, with all weights at the left, on zero. The pointer should be in the middle with nothing on the pan (if it isn't, ask the teacher to adjust it).

The right hand side of the beams goes up to the top, because the pan has gone all the way to the bottom with the weight of the rock.

Now move the middle weight - the hundreds - along. At 100 g, nothing happen. At 200 g, the right hand side suddenly drops to the bottom. The weight on the beams is now bigger than the weight of the pan. The rock has a mass of more than 100 grams but less than 200 g. Now you carefully move the hundreds weight back so it sits in the 100 gram slot. Your rock has a mass of "one hundred and something" grams.

The next step is to move the back weight - the tens - across. Again, nothing happens until you get to 90. This means that the rock has a mass of more than 180 g but less than 190. Again, we move the weight back until is sits exactly in the slot, and the pointer goes back up to the top. The rock has a mass of "one hundred and eighty something grams".

Finally you move the "ones" weight across until the pointer goes exactly to the middle:


You read the beam balance by adding the three figures together.


Common mistakes: the commonest mistake is to not put the big weights - the tens and hundreds - exactly into the slots. If they are between the slots, the mass measurement won't be accurate.


A problem with using the beam balance can be that it doesn't zero exactly. This shouldn't matter, because the most accurate way to use the balance is to weigh by difference. This is where you weigh your unknown in a container e.g. in a beaker. You then take it out and re-weigh the beaker without the unknown mass in it. You calculate the unknown mass from:

[mass of (container with unknown)] - [mass of (container only)] = [mass of (unknown)]

Since both the mass of the container with and without the unknown is wrong by exactly the same amount, they cancel out and the mass of the unknown is exactly right.


Some of the other equipment whose names you are expected to know and that you are likely to have to use at some stage through the year is: