The Decomposition of Ammonium Dichromate

What is Ammonium Dichromate?

Ammonium dichromate is an orange coloured crystalline substance.  It is a salt formed by reacting the base ammonium hydroxide with dichromic acid. It is because dichromic acid is a powerful oxidizing agent and the oxidation state of nitrogen atoms in ammonia is – 3, that ammonium dichromate is an unstable and reactive compound, that decomposes easily. This is because the salt anion has an atom in a high oxidation state which is capable to oxidize the nitrogen atoms from the ammonium cation, and vice versa. In the case of ammonium dichromate, ammonium nitrogen is oxidized to elemental nitrogen, while the chromium atom is being reduced to trivalent state.

What is the science behind the experiment?

As you can see from the reaction enthalpy below, the reaction is exothermic, which means that energy in the form of heat is released in the reaction. Although this is energetically possible, you will need to initiate the decomposition of ammonium dichromate by adding some external energy. This energy needs to be enough to overcome the activation energy barrier, after which the decomposition reaction continues spontaneously.

ammonium dichromate enthalpy equation

The volcano effect can be realized if we analyze the products of the reaction. Namely, elemental nitrogen and water produced in the reaction are both in gaseous state, while chromium (III) oxide is a green solid. The liberation of nitrogen and water vapor agitate the incandescent particles of chromium (III) oxide

The chromium (III) oxide that is formed in this reaction is very voluminous, so the volume is much greater at the end of the reaction than in the beginning, which gives the effect of a volcanic eruption.

How to conduct the experiment

What you will need



  • Large Container
  • Heatproof mat
  • Wooden splint
  • Fume Cupboard
  • Tongs
  • Watchglass
  • Blue cobalt chloride paper

Step 1

On a heatproof mat make a small conical heap (less than 50mm wide) of about 10 g of ammonium dichromate (VI). Place it on a larger metal tray to collect the large volume of chromium (III) oxide produced.  The whole apparatus should them be placed inside a fume cupboard.


Step 2

Soak a 3 cm length of a wooden splint in ethanol and put this into the top of the pile so that about 2 cm protrudes. This will act as a wick. See below for a diagram of how the experiment should look.


Step 3

Light the wick. As the wick burns down into the ammonium dichromate (VI), the orange solid begins to give off sparks and decompose into chromium(III) oxide, giving it the appearance of a volcano erupting.

Step 4

The ‘volcano’ reaction increases in rate and continues for 30 – 45 seconds. You can use tongs to hold a watch glass just above the erupting volcano for a few seconds. It will become steamed up with water vapour from the decomposition reaction.  You can confirm that this with blue cobalt chloride paper that will turn pink.

As all the ammonium dichromate may not react during the experiment it is highly recommended that you conduct the experiment in a fume cupboard, as ammonium dichromate is extremely toxic and may be carcinogenic.

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How To Change The Colour Of A Campfire

Sitting in front of a fire or enjoying the dancing flames with family and friends over good conversation is a great way to pass an evening. Adding some flair and colour to the fire with everyday items will astound your guests and make them squeal with delight. Several household items change the colour of a fire from standard orange and yellow to blues, greens and reds.


Things You’ll Need

  • One of several chemicals listed below
  • A fire
  • Personal protective equipment

The most important and first step is read all the warnings for this article. If you don’t, very bad things could happen.

Now determine what colour you want to change the flame to. The options are red, orange, yellow, green, turquoise, blue, purple, and bright white.

Now you need to get some of the material required to give you your desired colour, these are all available from

Here’s the breakdown by colour:

Colour Salts
Red Any Strontium salt like Strontium Nitrate
Orange Calcium Chloride
Yellow Sodium Nitrate, Sodium Chloride (Table Salt)
Green Barium salts such as Barium nitrate, Borax
Turquoise Copper sulphate
Blue Copper (II) Chloride (Campfire Blue)
Purple Potassium Permanganate
White Magnesium Sulphate

There are a few different methods you can use, they are listed below.

  • Toss dry colorants onto the flames.
  • Soak logs in an alcohol solution of colorants.
  • Soak logs in an aqueous (water) solution of colorants and allow the logs to dry.
  • Prepare pinecones, sawdust, or cork with colorants.

In general, there is no specific ratio of colorant to mix with the alcohol or water. Add as much powdered colorant as will dissolve in the liquid. Don’t attempt to mix colours together – you will probably end up with a normal yellow flame. If you want multicoloured fire, try adding a few different pinecones, each soaked with a single colorant, or scatter a mixture of dried coloured sawdust across the fire.

How to Prepare Pinecones or Sawdust

Remember to do this procedure separately for each colour. You can combine some sawdust, dry pinecones or any other absorbant material with different colorants later.

  1. Pour water into a bucket. Use sufficient water to be able to wet your pinecones, sawdust, or waste cork. (Skip to step 3 if you purchased your colorant in liquid form.)
  2. Stir in colorant until you can’t dissolve any more. For sawdust or waste cork, you may also add some liquid glue, which will allow the pieces to stick together and form larger chunks.
  3. Add the pinecones, sawdust, or cork. Mix to form an even coat.
  4. Let the material soak in the colorant mixture for several hours or overnight.
  5. Spread the pieces out to dry. If desired, pinecones may be placed in a paper or mesh bag. You can spread sawdust or cork out on paper, which will also produce coloured flames.

How to Prepare Logs

Follow steps 1 and 2 above and either roll a log around in the container (big container, small log) or else pour and spread the mixture onto the logs. Wear appropiate protective gloves to protect yourself. Allow them to dry. You can make your own newspaper logs by smearing colorant onto the newspaper before rolling it.

Points to Keep in Mind

  • Always take care and use the appropiate protective equipment when working with chemicals or fire.
  • Keep the colorants away from children and handle them with the care and respect due to potentially hazardous chemicals. Read and adhere to any warnings listed on product labels.
  • The element sodium burns with a yellow flame. The presence of this element can overwhelm any other colour. For this reason you should avoid using sodium if you are making a dry mixture.
  • If you are using alcohol-based colorants: Remember that alcohol is flammable. If you don’t allow it to evaporate before use, you will get a lighter-fluid effect. Use with care!
  • You should not try to colour the color of a barbecue, because although it will produce pretty flames it can also produce toxic fumes that will go into the food.

What Are E Numbers?

E numbers are number codes for food additives that have been assessed for use within the European Union (the “E” prefix stands for “Europe”).They are commonly found on food labels throughout the European Union.  Safety assessment and approval are the responsibility of the European Food Safety Authority. The numbering scheme follows that of the International Numbering System (INS) as determined by the Codex Alimentarius committee though only a subset of the INS additives are approved for use in the European Union. E numbers are also encountered on food labelling in other jurisdictions, including the Cooperation Council for the Arab States of the Gulf, Australia, New Zealand and Israel. The “E” prefix is omitted in Australia and New Zealand. They are increasingly, though rarely, found on North American packaging, especially in Canada on imported European products.

In casual language in the UK and Ireland, “E number” is used as a pejorative term for artificial food additives, and products may promote themselves as “free of E numbers” even though most of the natural ingredients contain components that also have an E number such as vitamin C (E300) or lycopene (E160d). Because vitamin C has an E number (actually several E numbers, 300-305, for different chemical forms of the vitamin), it is impossible to live on a diet without any substances that have E numbers. “Free of E numbers” then simply means that pure forms of the substances are not intentionally added, even though identical substances certainly exist naturally in nearly all foods.

What Do E Numbers Do?

Additives may be natural, nature identical or artificial. Natural additives are substances found naturally in a foodstuff and are extracted from this food to be used in another, for example beetroot juice with its bright purple colour can be used to colour other foods such as sweets. Nature identical additives are man made copies of substances that occur naturally. For example, benzoic acid is a substance that is found in nature and is made synthetically and used as a preservative. Artificial additives are substances made synthetically and are not found naturally.

Additives are used for a variety of purposes including to keep food wholesome until it is eaten, make the food look or taste better, ensure that the food is convenient to store or use, keep the price of the food competitive, make the food healthier (higher in vitamins or lower in fat) and aid in processing and manufacture.


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Classification By Numeric Range

100–109 Yellows
110–119 Orange
120–129 Reds
130–139 Blues & violets
140–149 Greens
150–159 Browns & Blacks
160–199 Gold and Others
200–209 Sorbates
210–219 Benzoates
220–229 Sulphites
230–239 Phenols & Formates (methanoates)
240–259 Nitrates
260–269 Acetates (ethanoates)
270–279 Lactates
280–289 Propionates (propanoates)
290–299 Others
Antioxidants & acidity regulators
300–305 Ascorbates (vitamin C)
306–309 Tocopherol (vitamin E)
310–319 Gallates & Erythorbates
320–329 Lactates
330–339 Citrates & Tartrates
340–349 Phosphates
350–359 Malates & Adipates
360–369 Succinates & Fumarates
370–399 Others
Thickeners, stabilisers & emulsifiers
400–409 Alginates
410–419 Natural Gums
420–429 Other Natural Agents
430–439 Polyoxyethene Compounds
440–449 Natural Emulsifiers
450–459 Phosphates
460–469 Cellulose Compounds
470–489 Fatty Acids & Compounds
490–499 Others
pH regulators & anti-caking agents
500–509 Mineral Acids & Bases
510–519 Chlorides & Sulphates
520–529 Sulphates & Hydroxides
530–549 Alkali Metal Compounds
550–559 Silicates
570–579 Stearates & Gluconates
580–599 Others
Flavour enhancers
620–629 Glutamates
630–639 Inosinates
640–649 Others
900–909 Waxes
910–919 Synthetic Glazes
920–929 Improving Agents
930–949 Packaging Gases
950–969 Sweeteners
990–999 Foaming Agents
Additional chemicals
New chemicals that do not fall into standard classification schemes

Using Sodium Bentonite To Seal Your Ponds

What Is Sodium Bentonite And How Does It Work?

Sodium bentonite products are used to seal large ponds, such as man-made fish ponds. The sodium bentonite clay properties are what make the material work so well as a sealant. Sodium bentonite swells to as much as eighteen times its normal size when wet. As it swells, it fills in the holes of a porous material, thus creating a watertight seal.

Sodium bentonite is so effective for this purpose that it has a wide range of uses. Not only do you find people sealing ponds with sodium bentonite clay, but you will also see bentonite clay use for construction waterproofing. Landfills, sewer drains, and similar installations are sealed using bentonite products.

How Does Bentonite Work?

Sodium bentonite is used as a sealant when ponds are leaking. The application can be done through “blanketing” the soil beneath the pond with the product. This has to be done before the pond is filled. The sodium bentonite prevents water loss as the pond ages (and a normal liner can be placed above it.) When applied to a sufficient depth, however, the bentonite itself acts as a sufficiently strong seal to stop leakage through to the soil.

If you have an existing pond that is leaking, you can use the blanket method, provided you drain the pond first. If you cannot drain the pond, the sprinkle method is your best option. Simply sprinkle granular bentonite on the water’s surface. The particles will sink to the bottom where they will saturate the porous places.

Pros and Cons of Sodium Bentonite Clay

Sodium bentonite clay has a number of attract properties as a sealant:

  • Its ability to swell and block moisture allows it to seep into the soil at the base of a pond in construction or to patch a pond that is leaking.
  • When applied at a thickness of up to 4″, sodium bentonite produces a seal that will withstand use by animals.
  • Sodium bentonite is much more affordable than sealing options. (It does, however, have to be applied by a professional.)

One downside to using sodium bentonite clay is that for proper installation, the pond must be drained. If you have fish, this is easier said than done. While you can use the sprinkle method and not drain the pond, this type of application is not fool proof. There is a chance that the clay particles will not reach all of the places in the soil that may be allowing leaks through.

If you want a good pond seal with sodium bentonite, you will need to have a professional apply the materials for the best results. This method is, however, the best way of sealing ponds, when you can afford to do it. Sealing ponds with sodium bentonite clay will create a watertight seal that stands up to years of use.

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How To Change The Colour Of A Hydrangea Plant With Aluminum Sulphate

Hydrangeas are fascinating in that, unlike most other plants, the color of their flowers can change dramatically.

It would be nice if one could change the color of hydrangeas easily. But for most of us, it is not easy. The people who have the most control over the color of their hydrangeas are those who grow them in containers. It is much easier to control or alter the pH of the soil in a container than it is in the ground.

On the other hand, hydrangeas often change color on their own when they are planted or transplanted. They are adjusting to the new environment. It is not unusual to see several different colors on one shrub the next year after planting.

It is much easier to change a hydrangea from pink to blue than it is from blue to pink. Changing a hydrangea from pink to blue entails adding aluminum to the soil.

Changing from blue to pink means subtracting aluminum from the soil or taking it out of reach of the hydrangea. This can be achieved by first treating the soil with a phosphorous based fertilizer followed by a treatment of lime or calcium. the pH should be raised to 6.0 to 6.5 but never higher than this.

That said, I’ll give the best information that I have on this subject and let you take it from there.

In order to change the flowers of the hydrangea from pink to blue there needs to be aluminium present in the soil and a pH of less than 7 ideally between 5.2 and 5.5 (Acidic). Only plants older than 2 years which are established should be treated. Before commencing treatment to change colour it is strongly advisable to water plants thoroughly every day for a week. Where possible test soil around hydrangeas for pH.

Add 15g (1 tablespoon) of aluminium sulphate in a litre of warm water and allow to sit for 15-30 minutes to dissolve. Add this to a watering can and make up to 5 litres with cold water. Apply the solution around the based of the hydrangea. DO NOT OVERUSE as making the soil too acidic can result in damage to the roots. Check the pH and maintain it between 5.2 and 5.5. Other simple things you can do include adding as grass clippings, coffee grounds and fruit or vegetable peelings to help lower pH levels. Potassium rich fertilizers will also help to achiev this.

Where to Buy Aluminum Sulphate online UK

Why Should You Use An Organic Weed Killer?

Why should you use an organic weed killer instead of a chemical alternative? There are many reasons! Firstly you are doing your part for the environment by not pumping the air and soil full of harmful chemicals.

Secondly using a more natural weed killer will be kinder to wildlife and household pets using your garden. Dogs and cats can be seriously injured or even killed by common weed killers used heavily in gardens.

reVert Organic weed killer is a non selective weed killer based entirely on natural and completely biodegradable ingredients including vinegar and sugar developed for the control of broad leaf and grass weeds. It is highly effective against dandelions, ragweed, daisy, foxtail, moss & algae, chickweed, liverwort, bindweed, clover etc.

It is ideal for weed killing on paths, patios and driveways and for spot treatment of weeds on lawns. Supplied as a ready to use product it eliminates any concerns about diluting.
Simply spray directly onto weeds, ensuring that the leaves are well wetted and leave to work.
The best and fastest results will be achieved if weeds are treated on a warm sunny day. Avoid spraying if weather is wet as this can cause the weed killer to spread into other parts of the garden.

It replaces the need for TOXIC herbicides and the effects are faster than commercially available weed killers. It does not create any health concerns for the operator and is safe to use around children and pets. Within a few hours the pH of soil returns to normal allow replanting in the treated area. When weeds are treated they will start to die almost immediately as the leaves become dehydrated and start to wilt, burning from the leaves right down to the roots and within 6 hours the leaves will turn black and the results are clearly visible.

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Using Ferrous Sulphate as a Moss Killer

There is only one compound available that kills moss in lawns, and that is iron sulphate; also known as Ferrous Sulphate. Its chemical formula is FeSO4. It is the moss killing component of moss killers and lawn sand and is commonly sold in the green keeping industry as a fertiliser. It may also be combined with other elements and can therefore be used as a general fertiliser.

The most common way of applying a ferrous sulphate based moss killer is to apply it a week or two prior to raking out the moss (see below for more details). The moss is partially desiccated and is thus easier to remove. However, there are two other opportunities to use it that may make moss control easier and more efficient.

Cost Effective Moss Control

Firstly we can use it to inhibit moss growth so that we enter spring with considerably less moss had we not taken action. By applying your iron sulphate moss killer, usually by sprayer or watering can during the moss growth period, anytime from late autumn through to spring you will at least kill the exposed upper layer of moss. Though iron sulphate is brilliant at killing moss it has its limitations when the moss is very deep. It will only penetrate 1 to 2cms into the moss so if you’ve got more depth than this the moss underneath may well remain alive. Therefore, if you know your lawn is prone to heavy moss infestations, starting your treatments in October before the moss gets too deep will be beneficial.

Even though the bottom layer of moss may remain alive, the killing of the top layer will stop light getting to the living bottom layer and the progress of the moss will be halted for perhaps 6 to 8 weeks. This is an easy and cost effective approach to moss control without the need for raking, particularly if your lawn is not smothered. This treatment can be repeated every 4 to 8 weeks over the winter months.

If at the same time you have improved the local environmental factors a little, together with improved lawn care practices, you may well have made conditions more favourable for the grass. This together with a moss killer could bring about the desired result. If not, then the moss will have to be removed.

More Efficient Moss Control

Secondly, you can use it after removal of the moss in the spring. Treating moss prior to removal will not kill all the moss; perhaps 20% to 50% will remain to re-infest your lawn. Therefore, if you treat what remains after raking you may well achieve upwards of 90% moss control.

How to Use Ferrous Sulphate as a Moss Killer

We would advise that initially you test a small area with a 1% Ferrous Sulphate Heptahydrate solution (10gms/1L of water). If this does not give the desired effect a stronger solution can be used up to a maximum of 5% Ferrous Sulphate Heptahydrate (50gms/1L of water).

A typical average strength to use would be a 3% solution. To make the solution add 30g of ferrous sulphate for every litre of water (for example for a 15L sprayer you will need 450g of ferrous sulphate).

Application of the solution should be at a rate of 5 square metres for every litre of chemical mix. Apply evenly over lawn etc avoiding overspray contact with other plants and paths, patios etc.

After 2 to 3 days you will see that the moss has turned black in colour indicating that the moss has been successfully killed. At this point one should use a tined rake to loosen and remove dead moss. Application of a lawnmower set to low cut will help in the removal. Please note: the grass cuttings and dead moss should not be added to compost bins.

Please be aware that ferrous sulphate is only for use on grass areas and is not designed to be used on hard surfaces as it may stain. For hard surfaces like roofs, paths, patios etc Zinc Sulphate can be used or a proprietary chemical like MossKill Premium.

If ferrous sulphate comes in contact with concrete for example it will stain the surface brown which effectively is a rust stain. To remove this stain one will need to use an acid solution like Oxalic acid (used as a 5% solution).

When treating lawns etc with ferrous sulphate keep pets off the surface for at least one week. This protects their well being and prevents transfer of residues onto hard surfaces (i.e. brown staining).

For application on agricultural pasture land / paddocks etc use at the same rates as above. Animals like horses must be kept of grasslands for at least 4 weeks before being allowed back to graze.

An over usage of Ferrous Sulphate can be harmful if the land being applied to has a low pH (very Acidic) as Ferrous Sulphate is naturally very acidic with a pH of 2.5.

NOTE: We must stress that this information can only be used as a guideline and is given in good faith. We cannot be held responsible for any adverse effects that may be experienced as a result of use of Ferrous Sulphate.

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