Playing with Hydrogel

Adding some water to Hydrogel.
We took about 7 cm3 of hydrogel . We extracted this from a clean dry Nappy.
You Need

Disposable nappies

A disposable nappy
Scissors
A large ice cream tub or similar container
Dessert spoon or similar measure
Stirring rod
Large beaker or plastic tub to hold at least 600 cm3
Plastic gloves for those with sensitive skin
a Cut the middle section out of the nappy – the thicker piece that is designed to absorb
the urine. Discard the other piece.
b Make sure the ice cream container is completely dry - wipe it with a paper towel if
necessary. Any moisture in the tub stops the experiment from working properly.
c Wear eye protection for the next step. Put the centre piece of the nappy into the ice
cream container and gently take it apart. Small white grains should start coming away
and this is what you are trying to collect. Keep gently pulling the nappy apart until you
have collected as many of the grains as you can. Do not do this roughly or you will lose
your product and put a lot of dust and fluff into the air. Avoid breathing in any of the
dust.
d Remove and dispose of all the fluff and other parts of the nappy, keeping the grains in
the bottom of the tub. They are heavier and fall to the bottom, which makes it easier to
separate them out.
e Estimate the volume of the grains.

Now the fun Bit

f Pour them into the large beaker and add about 100 cm3 of distilled water. Stir. Keep
adding  water until no more can be absorbed and stir between each addition.
Estimate the final volume of the hydrogel.

Now even more fun

g Add a dessert spoonful of salt and stir.

Poinsettia pH paper

To make the Poinsettia pH paper:

1. Cut the flower petals (actually specialized leaves called bracts) into strips
   
2. Place the strips into a beaker.
   
3. Add enough water to cover the plant material and simmer on a hot plate. 
   
4. Filter the liquid into another container (such as a shallow petri dish) and discard the plant matter. 
   
5. Saturate a piece of filter paper with the poinsettia extract. 
   
6. Allow the filter paper to dry and cut the colored paper into test strips. 

Motion Sensors to work out Distance Speed Graphs

Using the Motion sensor here we can do a series of experiments simultaneously to record the Distance, Velocity and acceleration of the cart as it moves down the track.

Here we are using a Lego trolley with a screen at the back to reflected the ultrasound signal.

The cart can be loaded with different masses.

Here are some distance time graphs to show four different runs at four different heights.

As the trolley moves down the track its velocity increases until it crashes at the end and the velocity drops sharply to zero.

1 was the shallowest
3 was the steepest.

Hot and Cold Water Diffusion

A classic way of showing diffusion is to add a small purple crystal to water and let it diffuse. By having two set ups one with hot water at around 80C and the other at 15C ( straight from the cold tap ) an idea is given on how temperature effects the rate of diffusion.

Using a Colorimeter to follow the rate of a reaction

With a new bit of kit I have been looking at the rate of reaction of an old favourite, HCl and Sodium Thiosulphate. This system has many advantages over the usual practical, not the least being that the reaction takes place in asealed cuvette so there is no smell and the amounts of substances are very reduced.

The Pasco software (in this case Saparkvue) makes recording this a breeze, creates the tables and graphs so that the data can the analysed easily.

A small amount of the chemicals are used ( approximately 6ml per experiment. The cuvette is filled with the required mixture and the placed in the calorimeter. This calorimeter records all the wavelengths at the same time so I don't have to worry about selecting the correct one, but simply the best one at the end of the experiment.

Before the experiment is started it is necessary to calibrate the colorimeter  but a cuvette of pure water, then it is simply a task of placing the solution to be examined in the cuvette and clicking start

The results can then be exported to word with any analysis. This system seems so much better value for money than other systems I have used.

Calculating the Specific Heat Capacity of Aluminium using Dataloging

I took a 1kg Mass of Aluminium and heated with an Immersion Heater for 10 minutes. After heating I left the Mass with the hrater in but switched off for another 3 minutes until the temperature settled.

The Al mass was insulated to prevent too much heat from escaping.
I used a PASCO  temperature probe to record the temperature change.

The blue line represented the temperature and the red line the voltage.

Temp start 20.7

Temp end  41.3

Voltage 10.1V Current 3.84A Time 600 secs

Mass 1 Kg

From this data we can work out the specific Heat Capacity of Aluminium

Energy in = Volts x Amps x Time

Energy in = 10.1.x 3.84 x 600 = 23270.3 Joules

SHC Al =  Energy In / Mass x Change in temp

SHC AL = 23270.3 / 1 x 21.6 = 1077.8 J/K

Its a bit high rather than the theoretical value of 913 but then the insulationwasn't as good as it could be.

What is the difference between Coding and Programming?

This seems to be a question I get asked very often.

Many people think and say that they are the same thing but there is a real difference.

Programming is generally about how to solve the problem what is often called the algorithm. It is about how to solve the problem. It can be written in English as a series of steps in how to solve the problem. Sometimes this is called pseudo code.

Coding is taking this program or algorithm and turning it into the actual computer program which is written in  a particular computer programming language, such as C or Python. The code would do the same thing but be written differently using the coding structures or syntax of the language you are using.

Many can code - they can take the algorithm and turn it into a computer program. What is much harder is to take an idea and turn this into a way of doing something. This is programming. This is the much harder problem.

Many courses teach people to code in Python or in  Java. Programming is really the topic of software engineering, examining the problem and working out the pseudo code in how to solve it. There are very few courses on this. Programming is the art of working out were to start and how to do it. It is not written in a specific language although some people do. They for instance program in Java; they think, solve the problem in the Language and code it it the same time. To them programming and coding are one and the same.

Using Data-loggers to speed up the process

Introduction to Data Loggers.

Experiments take time. And much of this time is often wasted trying to learn how to record. This is a very valuable skill but once learnt data-loggers can take over this chore and allow the student to do more learning and less recording.
Using state of the art sensors connected to a computer we can now carry out the experiments and pull out all the information about the process quickly and accurately and get to the learning point. Using these sensors we can also pull out other useful information which is otherwise not readily available to learn more about the processes. The data-loggers cover all aspects of Science and also cover all the A level Biology Chemistry and Physics.

The sensors are linked directly to the computer. They capture data every few fractions of a second and send this to the computer where the data is displayed in a table for the student to work on or more usefully as a graph to display the features of the experiment.

The data-loggers enable far more complex experiments to be carried out and in a fraction of the time taken to do the experiments manually. This is also good preparation for business where things are usually carried out by machine and the students can see for themselves how processes work in a more business like and professional manner.
Using this data-logging equipment gives the child an advantage over others so that they can become better scientists.

Schools opt for less subjects but better grades

This is a sample of some of the emails I receive

"My child wants to do triple science, but has been told that the school will only enter them for double, as they believe this will 'maximise the child's grades and therefore their life chances'.  i.e. they would rather the child got two As or A*s than risk getting 3 Bs." 

I agree.  This is a load of rubbish, but is a problem that schools are making on their own.

Very commonly schools believe that students cannot improve. 

Schools are ranked on what grades the students get. It is in your childs schools interest that your child takes fewer subjects with higher grades than taking more subjects and possibly getting a lower grade. 

The school can now only count the first time a student takes an exam for their performance figures.

This is often why this rule about double / triple science exists. The school does not want to have any poor grades. The schools are scared of  a child  getting lower grades which will lower the schools performance average.

It is in the schools interest that your child does less subjects with better grades and nothing to do with your childs progress.

It seems that schools are out for themselves and not putting the child first - just to get higher up a league table. What is the benefit to a school that has good league table results if it doesn't try to help children suceed

A use for Lego Znap A DNA Model

 I have some old Lego Znap. It was part of a Lego experiment to compete with K'Nex. Its not much use and after having a look in one of the science catalogs selling K'Nex as a DNA molecule I thought I would have a go making a DNA strand with it

Here are the results. an 8 base pair set - I didn't have any more connectors. The set can be twisted into a double helical structure and since the stuff was just lying around it has found a good use.

The Znap has four colours here red - green and black - yellow making the different base pairs.
It will do until I can get a much better model and that won't be K'Nex either.

Starch Amylase Experiment

I made up a starch solution  with 1/4 teaspoon  of starch dissolved in about 100ml of water I used soluble starch but corn starch will do or even the water from boiling potatoes.
I had a failure with the experiment the last time I did it with a student so I tried the same chemicals again to test to see if they worked. Into the first tube I added some starch and a few mls of a 1% Amylase solution. Into the next tube I put the same amount of starch and 2-3 mls of spit - I know this enzyme works.

After 20mins I took a sample of each of the tubes and added a squirt of Benedicts reagent and placed in a beaker of near boiling water for a few minutes. The left hand tube with the commercial Amylase powder enzyme turned the brown colour - confirming that the enzyme was working and converted some of the starch to maltose.

The middle tube went green showing that the Amylase in my mouth worked - slower - but some Maltose was made.

The tube on the right with just starch and no enzyme did not change showing that Starch does not react with Benedicts solution and there was no Maltose present in the starch.

So the Amylase enzyme does work and does convert starch to Maltose which is a reducing sugar (the Benedicts Test)
My spit works too albeit slower.
Now why did this not work for the student? I have no idea.

Kipps Apparatus

I bought a Kipps apparatus to generate Carbon Dioxide Gas or Hydrogen Gas. I don't need very much or make it that often so gas cylinders are a waste of time. It is a fascinating piece of equipment which is so simple to use.The Kipps generator was invented in 1844 by Petrus Jacobus Kipp and was used throughout the rest of the 19th and the entire 20th centuries for making gases.  Kipp generators are still being used in some places even now because of their ability to make a gas and then stop and then to be turned on again.
The Kipps apparatus is used to make a variety of gases such as Carbon Dioxide, Hydrogen and Hydrogen Sulphide. This is often why the Kipps apparatus was often left in a fume cupboard in the back of a classroom for all to see.
To make hydrogen gas some granulated zinc is put into the middle vessel by removing the  stopper.
Acid is then poured into the top vessel which is connected by a glass tube to the bottom vessel.
When the chemist requires the gas the valve in the middle chamber is opened and this allows the acid in the top chamber to force by air pressure the acid in the lower chamber into the middle chamber. The acid mixes with the zinc and there is a reaction. The zinc reacts with the acid and generates hydrogen gas. If the valve is open then the gas is collected often under water into a gas jar.
When enough gas has been collected the valve is turned off. The pressure in the middle chamber starts to increase and pushes the acid out of the middle chamber back into the bottom and also into the top chamber. When all the acid has been removed the reaction stops because there is no longer any acid to react with the zinc.
The Kipps apparatus is very simple to use, interesting to understand how it works and gives a good insight to how old fashioned ideas are still good to use today

Convection Currents in a beaker of water

 One of my A level students yesterday had never seen convection currents in water, so I set up this simple experiment for him. Into a large beaker I poured some cold water and at the bottom I placed a small coloured crystal.
I heated the water with a burner and watch as the water heated,  the water coloured by the crystal rose up in the beaker - not straight as the books suggest but in a more spiral direction until they reached the top when they spread out even more.

The water showed that it was less dense than the water around it because it was hotter and therefore it was lighter and rose to the surface - albeit not in a quite vertical direction.

There we are warm water rises and disperses the heat around the beaker from the bottom to the top.