Malus Law

Shining a light through two polarising lenses. The first cuts out all the light except in one plane. Rotating the other into a plane at 90 degrees, can wipe out the other. Try looking at a led TV screen (polarised light) with polarising lenses and see what happens as you rotate them.

A Really Sharp Pencil

The most useful item in a student's toolkit is the sharp pencil, long enough to hold and make sure its really sharp. Always have one pencil or better still two. Used lots in Science and Maths too. For graph work a sharp pencil can get an extra mark for those points being accurate, and a sharp pencil improves the line. A good rubber (not one on the end of a pencil) makes the mistakes easier to change.

A tall order "hiding a light under a bushel" and do a fun chemistry experiment about that. But we managed to put the fire under the bushel out with a homemade fire extinguisher

Alcohols to Acids

Butanoic Acid is made from heating butan-1-ol with Acidified Potassium dichromate and refluxing for 30 minutes of so. The potassium Dichromate changes from orange to green as it is reduced and the alcohol is oxidised. After the reaction is complete then the apparatus is changed and set up as in the photograph to allow the butanoic acid to be distilled off from the mixture leaving the chromate behind and the butanoic acid is collected in the conical flask.

Maths Tools, Whats needed

A good compass, with a built in pencil. It needs to be firm not loose.
360 degree protractor for doing bearings
A 30cm ruler with a slot in the middle for doing best fit lines
A bendy line for drawing curves
An irish compass very accurate for drawing circles with two pencils
Isosketch for drawing those plans and elevations
A good pencil sharpener

Measuring acceleration - Couple of videos

Using a mass over a pulley and a light gate to measure the acceleration due to gravity.

 or using the old fashioned ticker tape timer to measure the trolley accelerating down a slope

Diffusion ISA Ideas for AQA

One way of doing this experiment is to add a crystal of KMnO4 to a large beaker containing 1 litre of water and waiting. In the images the breaker on the right was at 65C and the one on the left at 12.9C.

A small crystal of KMnO4 was dropped into the beaker and left for a short time.

The only problem with this experiment is that it is very difficult to quantify the rate of diffusion, so we are going to modify this experiment and use a colorimeter instead.

The better alternative.#

We used a colorimeter with pasco Sparkview software to observe the rate of diffusion.

A small crystal ( just under the cuvette in the picture) was placed into the cuvette and added to the colorimerer which recorded the results.

Measuring the green absorbance the graph above was produced as the KMnO4 cystal dissolved and spread throughout the hot water.