Blue ruby

This post contains a collection of animated gifs and other pictures from experiments we have been doing recently.

First a heart made by putting copper foil into silver nitrate solution (copper is more reactive than silver and displaces silver ions from solution).

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Silver heart

Next, heating a beaker of ice to water and steam.

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Ice water steam

Those are anti-bumping granules you can see at the bottom of the beaker in the boiling water.

Now for a rather pretty B/Z reaction we carried out recently.

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A Belousov-Zhabotinsky reaction

Captured using time-lapse mode

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99 pictures at 15 seconds interval

Finally, the curious case of the colour of chromium (III) ions in water. And hence the title of this post ‘Blue ruby’.

When asked “How do you make a blue heart red?”
“With a torch and chromium (III) ions”, I said

Jim Clark, writing on Chemguide.co.uk notes that “The simplest ion that chromium forms in solution is the hexaaquachromium(III) ion – [Cr(H2O)6]3+.” He also goes onto say that “The hexaaquachromium(III) ion is a “difficult to describe” violet-blue-grey colour.”

Our AQA A’ level Chemistry describes [Cr(H2O)6]3+ as being ruby in colour, but our solution of chromium (III) chloride definitely looks blue to me.

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chromium (III) chloride solution

That is, until one looks at it under torchlight (tungsten filament bulb), then
indeed it does appear a ruby colour.

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blue or ruby?

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Use a torch

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shine a light

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then you’ll see ruby delight

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off on off

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has that boiling tube got a red eye?

 

Sweet TLC hydrolysis

Aspartame sweetener is a modified dipeptide. When aspartame is reacted with 6M hydrochloric acid the peptide bond should be hydrolysed (broken), producing aspartic acid and phenylalanine methyl ester. The methyl ester may also be hydrolysed, depending on the severity of the conditions.

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Whiteboard of the aspartame hydrolysis by my friend and colleague Tony Pluck

We carried out a hydrolysis reaction by boiling aspartame sweetener (one individual sachet) with 10ml of 6M HCl in a boiling water bath for 30 minutes. The results were analysed using thin layer silica chromatography, (silica TLC).

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Running a chromatogram (silica TLC plate)

Samples of aspartame sweetener were spotted before and after the hydrolysis, together with phenylalanine and aspartic acid standards.

The plate was run in a solvent system of butan-1-ol (12ml), glacial acetic acid (3ml) and distilled water (6ml) taken from the old Nuffield A’level Chemistry textbook .

After allowing the solvent to run up to within a few cm of the top of the plate it was removed from the beaker and dried using a hot hair dryer. The TLC plate was then sprayed with ninhydrin and heated in an oven at 110 C for approximately 10 minutes.

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Samples left to right, phenylalanine, hydrolysis mixture, aspartic acid and aspartame sweetener.

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Same as the above with labels on the plate

Another experiment was carried out, identical to the above except with a much shorter hydrolysis time (of about 3 minutes). This was to see if the whole experiment could be done in a 55 minute period of chemistry at school.

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The same again with a much shorter hydrolysis time of a few minutes

We want to run further chromatograms spotting smaller samples, as both of the above plates suffered from streaking due to sample overloading.

 

 

Tropical freeze

Cool a bottle of water in the freezer compartment of a refrigerator and it is possible to supercool the water below its freezing point for a short period of time. If one removes the bottle and gives it a sharp bang on a hard surface the rapid formation of ice crystals ensues in what is popularly referred to as the ‘instant ice’ experiment. I’ve been trying to capture the instant ice freezing experiment on camera for several weeks now without much success.

One of the biggest problems of doing this experiment in the tropics is that as soon as the bottle is removed from the fridge condensation forms on the outside of the bottle. This prevents one seeing whats going on inside.

If you try this at home I can only repeat the advice given on several You Tube movies; use as many bottles as you can and keep monitoring them to arrive at just the right moment to take them out by trial and error. My 600ml bottle took somewhere between one and a half to two hours.

Tropical freeze…

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Whoosh brothers

The whoosh bottle demonstration involves setting light to methanol vapour in a thick walled 20L water bottle. By adding a few drops of water into the methanol, salts such as LiCl, NaCl and KCl can be incorporated into the ignition mixture and add colour to the resulting flame.

Here are some images of the same.

First three pictures of the experiments:

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Lithium whoosh – the bottle on the right did not ignite.

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Sodium whoosh – only the middle one

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Potassium whoosh

Next are three animated gifs of the experiments:

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What colour do you see in the flame in the bottle? Is it the characteristic flame colour from Li, Na or K?

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Tried for a triple whoosh, but only the middle one worked. Was it Li, Na or K?

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Better colours with the lights out? It’s usually difficult to see the colour of the flame with this shy violet. Li, Na or K?

The whoosh brothers! A composite gif animation of all the above.

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Whoosh brothers!

Try as I might I could not get more than one bottle to ignite at a time. Movies uploaded to You Tube soon.

 

SAFETY

Follow appropriate safety guidelines when igniting the bottles. Methanol vapour is toxic. Only use thick walled plastic bottles. Do not try more than one ignition per bottle. Wash each bottle by filling completely with cold water after each ‘burn’. Our laboratory was ventilated with the all the windows open after the each experiment for more than an hour.

Flatlines

Ice to steam or I can sing a heating curve.

Can you identify the songs?

Here are some karaoke lyrics to substitute in for songs on stages of the heating curve for ice to steam (temperature against time).

Stage 1 – Song 1

“Temp low, sweet ice a lot

All the vibrations are slow

Add heat, start warming up

Vibrations mean the ice is going to go”

Stage 1 – Song 2

“Ice picking up good vibrations

Heat giving it excitations” repeat

Stage 2 – Song 3

“At nought degree C, I want to break free

To break free from your bonds takes energy

Molecules, use heat to break free”

Stage 3 – Song 4

“All the molecules liquid now

All the molecules move around

Molecules keep on moving round all night long

Heat it up, heat it up, baby heat it up

na na na na na na na na 

Temperature going up, going up, water getting hot”

Stage 4 – Song 5

“I am boiling, I am boiling

Steam again, breaking free

I am boiling, no more bonding

Temperature constant, 100 degrees C”

Stage 5 – ???

 

 

Phase change flatlines

A New Year’s Eve Chemistry Karaoke challenge. Examine the picture below which shows a heating curve for ice through to steam. The challenge is to come up with karaoke lyrics to popular songs of your choice which fit the regions on the curve 1 to 5 describing the behaviour of the water molecules. Students often have difficulty in explaining why the temperature does not increase during the regions of the curve representing phase changes; solid ice to liquid water (2.) and liquid water to gaseous steam (4.). Thus, the added challenge is to explain the reasons for these ‘flatlines’ in your karaoke lyrics.

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Magnesio

Magnesio is magnesium in Spanish. We cut out a small figure in magnesium metal and stuck a little manganese (IV) oxide to its arms and head using Superglue.

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Magnesio

We then dropped the figure into a luminol reaction mixture set-up in a measuring cylinder containing layers of sucrose solutions as described in March 2015. It needed a little prodding with a glass rod to get it to submerge at first, but then started bobbing up and down as shown in the animated .gifs below.

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The luminol reaction mixture is in the sucrose layer between 15 – 60 ml

The bottom layer of sucrose solution solution contained some 4M hydrochloric acid so that when the magnesium sank down that far, it reacted with the acid producing bubbles of hydrogen, causing it to float up again.

When the magnesium rose up into the topmost layer, which was 0.5M iron (III) chloride, it probably got coated with the dark green iron containing precipitate formed there, which may have helped it to sink again.

The middle of the measuring cylinder contained the luminol reaction mixture, (potassium hydroxide, luminol and 6% hydrogen peroxide solution).2015_11_21_magnesio_01_20

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Blue bubble ghost?

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No, it’s Magnesio!

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Finally, when the luminol reaction was over, Magnesio was washed out into the sink.

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Luminol all used up, where’s Magnesio?

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There he is, in the sink!

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Relaxing after a swim on a paper towel

Maybe you will be able to see a Magnesio adventure soon.

See the movie file on You Tube

The three metals attracted to the neodymium magnet last time were nickel, cobalt and iron.

 

 

Magnetic attraction

Nickel (II) salts, like nickel (II) sulfate, are classed as category 1 carcinogens and colbalt (II) salts, like cobalt (II) chloride, are category 2 carcinogens. As such, neither of these two kinds of salts are recommended for use in experiments at school.

Setting up

Setting up

What follows is a description of some displacement reactions which were carried out on a microscale in order to minimise the hazards like the ones mentioned above. The experiments involved adding magnesium ribbon to small volumes of aqueous solutions of some transition metal salts.

Small pieces of magnesium ribbon were dropped into approximately 1.5ml of each of the following solutions:

1M manganese (II) sulfate
0.5M iron (II) chloride
1M cobalt (II) chloride
1M nickel (II) sulfate
0.5M copper (II) sulfate
and
0.5M zinc sulfate.

After several minutes a small neodymium magnet was waved over the magnesium metal strips. The results are summarised in the gif animations below.

Microscale displacement reactions using magnesium

Microscale displacement reactions using magnesium

Zinc and copper

Zinc and copper

Manganese and iron

Manganese and iron

Nickel and cobalt

Nickel and cobalt

The animations were constructed from a movie of the reactions which can be viewed on You Tube here.

Which pieces of magnesium were attracted to the neodymium magnet and why?

All the colours of a tomato

Toxic cocktail - tomato juice with a splash of bromine water

Toxic cocktail – tomato juice with a splash of bromine water

Lycopene is the molecule responsible for much of the red colour of tomatoes.

The conjugated double bonds absorb certain wavelengths of light

The conjugated double bonds absorb certain wavelengths of light

When bromine water is added to tomato juice, various addition reactions occur, with bromine molecules reacting with some of the double bonds in the lycopene molecules.

The wavelengths of light absorbed by the brominated products probably depends on the number of conjugated double bonds remaining, i.e. not reacted with bromine. In any case, many different colours are seen ranging from yellow to green and blue.

Here’s an animation of one such experiment. First bromine water is added to tomato juice in a measuring cylinder and then the mixture is stirred with a glass rod.

Re-colourising tomato juice

Re-colourising tomato juice

Almost a rainbow!

The brominated tomato juice shows various colours.

The brominated tomato juice shows a variety of colours.

We also wanted tp see what happened when chlorine water and tincture of iodine were added to tomato juice.

Before adding the halogens

Before adding the halogens

After adding the halogens to tomato juice

After adding the halogens to tomato juice

In close-up

Chlorine water + tomato juice close-up

Chlorine water + tomato juice close-up

Bromine water + tomato juice close-up

Bromine water + tomato juice close-up

Tincture of iodine added to tomato juice close-up; outside in bright sunlight

Tincture of iodine added to tomato juice close-up; outside in bright sunlight

Unsurprisingly, the chlorine water bleached the tomato juice white, whilst the tincture of iodine produced some interesting, if quite dark, green and blue colours after some time.

In summary, some interesting colours were seen in the tomato juice, although these demonstration experiments must be carried out in a fume cupboard. They can lead onto a discussion of addition reactions in alkenes and a test for alkenes, such as ethene, by decolourising bromine water.

Index & Contents 07/12 to 07/15

Index & Contents – July 2012 to July 2015

To go to a post in the contents list below, click on the relevant month in the Archives list on the right hand side of the page.

July 2015
PALT
A holiday quiz where nearly all of the answers are Al (aluminium) or Pt (platinum).
A .gif animation is shown of an experiment where aluminium and platinum foils were introduced into a blue Bunsen burner flame side by side.

June 2015
Rust on a melon
We showed numerous pictures and .gif animations for some oxidation and reduction reactions involving iron. In summary the reactions were:
Oxidation
1. Rusting of iron nails, including a .gif animation of nails in an experiment lasting three and a half weeks investigating the factors necessary for rust formation.
2. Burning sparklers, including a .gif animation.
3. Speeding up the burning of iron wool by whirling it around on the end of a length of string (.gif animation).
Reduction
4. A thermit reaction carried out at night over a water melon, including a .gif animation.

May 2015
Balls of fire
We described a rapid, small scale method for making nitrocellulose without producing large amounts of waste. We experimented with using potassium carbonate, lithium carbonate, limewater (calcium hydroxide) and barium carbonate in place of sodium hydrogencarbonate to neutralise the acid reaction mixture. As a result, nitrocelluloses were produced which gave different burning characteristics and flame colours.
Ten .gif animations are shown, one each at normal speed and one in slow motion for sodium, potassium, lithium, barium and calcium impregnated nitrocelluloses.

April 2015
Food colour frenzy
We repeated the dancing droplets of food colour reported by Nate Cira, Adrien Benusiglio and Manu Prakash. Five .gif animations are shown of the droplets moving on microscope slides. We found that red food colour was best at pushing around all the other colours. We also posted a movie ‘Red Peril’ Food Dye which can be viewed here: https://www.youtube.com/watch?v=IKY-Zqa7R10

March 2015
More fun with luminol
We describe a novel way of showcasing the classic luminol chemiluminescent reaction by carrying it out in a dense layer of sucrose solution at the bottom of a measuring cylinder, which also contained hydrogen peroxide. A second less dense layer of sucrose is layered on top of this mixture and serves as a barrier to a third top layer which contained iron (III) chloride and copper (II) sufate solutions. The reaction was started by dropping a small piece of lead metal dipped in manganese dioxide powder into the measuring cylinder.

The oxygen bubbles produced by the decomposition of the hydrogen peroxide rise up the measuring cylinder and are surrounded by blue lighht from the luminol reaction.
A movie of the reaction can be viewed here: https://www.youtube.com/watch?v=mt8EX4pZuJU&feature=youtu.be

February 2015
Bicarb rockets
Numerous pictures and seven .gif animations of Bicarbonate Rockets, which are often made at school. These rockets are constructed from plastic bottles and fuelled with a reaction mixture of vinegar and sodium bicarbonate. The two reactants produce carbon dioxide gas, but it is the force of the liquid reaction mixture blown out of the bottom of the bottle by the carbon dioxide which provides most of the upward lift. The most critical design feature for our rockets was finding a plastic bottle with a neck of just the right size diameter to match our medium sized rubber bungs.

January 2015
Propane rockets
Numerous pictures and four .gif animations of Propane Rockets made using a plastic bottle and a mixture of oxygen and bottled gas. These can be used to illustrate stoichiometry and balanced chemical equations when studying chemistry at school.
Details of the .gif animations are as follows; three (normal speed) .gif animations showing:
1. Complete combustion of the fuel (enough oxygen) and a very fast rocket.
2. Incomplete combustion (not enough oxygen) and a slow moving rocket.
3. Incomplete combustion (not enough oxygen) and failure to launch.
The fourth .gif animation is a slow motion animation constructed from a high speed movie shot at 1000 frames per second. It shows the fuel burning down the bottle as the rocket takes off.

December 2014
Match head rockets
Numerous pictures and four .gif animations on how we make our Match Head Rockets in Chemistry Club.
Also, three pictures and a .gif animation showing the products of the two experiments featured in the November 2014 post.

November 2014
Two exothermic chemical reactions commonly carried out at school
1. Iron and sulfur
A .gif animation and other pictures are shown for the reaction which takes place when a mixture of iron filings and sulfur are heated together in a test-tube. Iron sulfide is produced.
2. Copper (II) oxide and carbon
A .gif animation and other pictures are shown for the reaction which takes place when a mixture of copper (II) oxide and carbon are heated together in a test-tube. A thermal reduction takes place leading to the formation of copper metal.

October 2014
Fun with luminol
Variations on the classic demonstration reaction utilising the chemiluminescence of luminol.
In one experiment the luminol reaction mixture was poured into a Petri dish and drops of iron (III) chloride and copper (II) sufate solutions were dropped into it using pipettes. Flashes of light were produced around the droplets as they fell into the reaction mixture.
In a second experiment the luminol reaction mixture was again poured into a Petri dish, drops of iron (III) chloride and copper (II) sufate were added and then the mixture was electrolysed using carbon electrodes and a 9 volt power supply.
A .gif animation is shown for each of these two experiments.

September 2014
Strawberry blonde
Demonstrating the bleaching effect of hydrogen peroxide solution using strawberries and the effect of temperature on the rate of these reactions.
Includes:
A .gif animation of a frozen strawberry warming up to room temperature next to a strawberry already at room temperature, (the former goes all squashy).
A .gif animation of a strawberry dropped into 6 vol hydrogen peroxide in a small beaker.
A .gif animation of a frozen strawberry and a room temperature strawberry dropped into beakers of hydrogen peroxide side by side.

August 2014
Unreactive metals
On the reactivity series of metals studied at GCSE level in chemistry and reactions of magnesium, zinc, iron and copper with 2M hydrochloric acid.
Includes a .gif animation showing the four metals reacting with 2M hydrochloric acid for approximately a minute, then a second .gif animation showing the reaction of an iron nail and a piece of copper foil with 2M hydrochloric acid over a period of a week.

July 2014
What does the word ‘salt’ mean?
On the two meanings of the word salt in chemistry at school.
A .gif animation showing the build up of a 3D digital image modelling the cubic shaped ionic lattice of sodium chloride.

June 2014
A celebration of IYCR, The International Year of Crystallography 2014
A lot of images of crystals of ionic compounds encountered by students at school, including thirteen .gif animations of crystals growing, as seen under a microscope.

The crystals shown in order of appearance are:
Sodium chloride
Sodium bromide
Sodium iodide
Potassium chloride
Potassium bromide
Potassium iodide
Ammonium sulfate
Magnesium sulfate
Copper (II) sulfate

May 2014
Flame tests
The colours seen in web images for flame tests vary.
There are .gif animations for lithium, sodium, potassium and calcium flame tests.

Alkali metals in water
A .gif animation of lithium, sodium and potassium metals added to a small bowl of water at the same time from a spatula.
Three .gif animations, one each for lithium, sodium and potassium metals, added to a small bowl of water individually.
A .gif animation showing lithium, then sodium, then potassium metals being added to a large trough of water sequentially.

April 2014
Great snakes!
When a mixture of sucrose (4 parts) and sodium bicarbonate (1 part) is doused with ethanol and set light to, trailing ‘snakes’ of dark grey ash emerge from the flames.
Includes a .gif animation of the experiment and another illustrating the artistic qualities of the ‘snakes’ produced.

March 2014
The chromatography of chlorophyll
Thin layer silica chromatography of a chlorophyll containing extract from grass. We used a 70:30 mixture of diethyl ether : petroleum ether (bp 60-80) as the eluting solvent. Includes numerous images of the procedure and a .gif animation of the elution of a TLC plate and pigment separation.

February 2014
Glowing things
On the u.v. fluorescence of quinine (from tonic water) and chlorophyll (from spinach). The .gif animations show the following subjects illuminated by alternating u.v. light and fluorescent light.
A .gif animation of jelly made with and without the addition of tonic water in plastic cups.
A .gif animation showing the red colour of spinach juice.
A .gif animation showing a ‘spooky vampire smiley face’ fashioned from jelly made with tonic water and spinach juice.

January 2014
Snow from brine
Making ‘snow scenes’ from cardboard soaked in saturated sodium chloride solution spiked with a few drops of potassium hexacyanoferrate (II)

Modelling a sodium chloride crystal
A .gif animation showing a rotating model of the sodium chloride crystal lattice, made from brightly coloured modelling clay.

December 2013
Rudolf the red-nosed boiling tube
A Christmas themed Santa’s challenge experiment, involving the reaction of sodium hydrogencarbonate and calcium carbonate with hydrochloric acid.

Belousov–Zhabotinsky reactions
.gif animations of B/Z reactions in a beaker (one animation) and in Petri dishes (five animations)

November 2013
High speed photography and .gif animation of the explosive reaction between hydrogen and oxygen bubbles and a high speed .gif animation of the hydrogen “pop” test.

October 2013
Halloween Chemistry 2
Pictures showing the use of fluorescent inks extracted from highlighter pens in a Halloween themed display under u.v. light.

Hydrogen chloride and ammonia diffusion experiment
A .gif animation showing the diffusion of hydrogen chloride and ammonia gases which react to form a ‘white smoke’ of ammonium chloride in a glass tube. In the experiment we used a temperature probe to show the exothermic nature of the reaction.

September 2013
A .gif animation showing the explosion produced when a mixture of hydrogen and oxygen bubbles are lit with a burning wooden splint.
A .gif animation using Lewis diagrams to illustrate the balanced equation for the reaction between hydrogen and fluorine.
A .gif animation showing the diffusion of hydrogen chloride and ammonia gases in a glass tube and reacting to produce ‘white smoke’ of solid ammonium chloride.

August 2013
When hydrogen met fluorine, including a .gif animation showing bond formation in a molecule of hydrogen fluoride.

July 2013
Explaining the results seen in the halogen/halide displacement reactions June 2013 .gif animation. Chlorine displaces bromide ions and iodide ions from solution. Bromine displaces iodide ions from solution.

June 2013
Halogen/halide displacement reactions in aqueous solution
A .gif animation showing iodine, bromine and chlorine added to NaCl, NaBr and KI.

Fluorite
Two .gif animations, one illustrating the formula of calcium fluoride (fluorite) and a second showing the fluorescence of fluorite under u.v. light.

May 2013
Testing for chlorine
A .gif animation of the bleaching effect of chlorine on some orange flowers.
A .gif animation showing chlorine gas bleaching red and blue litmus paper.

April 2013
Testing for carbon dioxide
A .gif animation of an experiment illustrating the thermal decomposition of copper (II) carbonate and testing the carbon dioxide gas produced by bubbling it through limewater
A .gif animation showing a large carbon dioxide bubble bursting and extinguishing six burning candles placed around it.

March 2013
Testing for hydrogen and oxygen gases
Three .gif animations of test-tube reactions; testing for hydrogen gas with a burning wooden splint, testing for hydrogen with a hot piece of platinum foil and testing for oxygen with a glowing wooden splint.

Testing for water using cobalt (II) chloride
A .gif animation of cobalt chloride paper used in testing for water; blue when wet (hydrated), pink when dry (dehydrated). Cobalt (II) chloride is also sometimes used as an indicator in the silica gel drying agent used in desiccators, but it is toxic.

February 2013
Testing for water using copper (II) sulfate
A .gif animation of a simple dehydration experiment heating hydrated copper (II) sulfate in a test-tube with a Bunsen burner and then adding water to it.

January 2013
The colours of copper (II) chloride, copper (II) nitrate and copper (II) sulfate crystals in pictures, a laboratory desiccator and its effect on hydrated aluminium sulfate over time.

December 2012
Coloured crystals to illustrate the “Halloween Chemistry” poem, fake blood, green copper (II) chloride in a Santa illustration, wet lithium chloride crystals and a silver bearded wolf’s head

November 2012
The shapes of large NaCl, NaBr, NaI crystals in pictures

October 2012
“Halloween Chemistry” poem, KCl, KBr, KI crystals in one picture

September 2012
Periodicity

August 2012
The Periodic Table, lithium fluoride and sodium chloride

July 2012
Ionic bonding and the sodium chloride lattice