Choosing the chemicals to start with
On this page, a guideline for which chemicals to purchase is given. Especially, when you start with a home lab, it may be difficult to determine, which chemicals you need first. Chemicals are quite expensive, so, especially when budget is limited, it is wise to think things over, before buying.
Another important thing is not to buy too much of chemicals. Many aqueous chemistry experiments can be done on a micro scale with less than 100 mg of chemicals and volumes of no more than a few ml. This makes experimenting less expensive and produces small amounts of waste. Only if one wants to demonstrate something to a larger group, larger quantities may be needed, but for private experimenting, using larger quantities does not add any other dimension to the experiments. Of all the chemicals, except the acids, 100 grams frequently is more than enough. Even with 50 grams hundreds of experiments can be done. For the common mineral acids, it is best to start with 1 liter for each acid.
For dry chemical experiments, it also is wise to work with sub-gram quantities. This makes these experiments much safer and if something gets out of control, then the consequences usually are not that bad with such small quantities.
Below follows an overview of chemicals, which are most interesting to start with. There is no need, to buy all of these chemicals at once. For all chemicals, mentioned below, you will need a few hundreds of dollars, even if only purchased at 50 gram quantities. My own experience is that building up a home lab over the course of many years is more rewarding. One can best choose a certain theme (e.g. halogen chemistry or transition metal chemistry) to start with and explore that theme.
Separation of properties of chemicals
When purchasing chemicals, it is important to buy the ones, which only have a single main property. Many inorganic chemicals are more or less ionic and consist of a cation/anion pair. An example is sodium chloride, consisting of Na+ ions and Cl– ions. Of such ionic compounds, the properties are determined by both the cation and the anion. Frequently, inorganic chemicals are such, that either just the cation or just the anion has a specific property and the counter-ion is just a charge balance, not taking part in any interesting reaction, for which the chemical is intended. Such a non-reactive ion is called a spectator ion.
Fortunately, there are some cations, which in practice have no effect and always are spectator ions in practical situations. For anions the situation is somewhat different and there is not a single anion, which safely can be regarded as spectator ion in all cases.
When a compound is purchased, because of its anionic properties (e.g. dichromate, permanganate), then the cation should be a non-reactive one like sodium or potassium. When a compound is purchased, because of its cationic properties (e.g. copper (II), hydroxylamine), then a safe choice frequently is to buy the sulfate. Sometimes chlorides or nitrates also are suitable.
This separation of properties really is important. Imagine that you want to study the properties of permanganate ion, but the only permanganate available in your home lab is silver permanganate (a commercially available compound, although probably not for the general public). When you dissolve this compound in water, then you always have the properties of silver ions interfering (e.g. formation of precipitates with chlorides). For this reason, it really is preferable to have sodium permanganate or potassium permanganate. These let you study the properties of permanganate ion without interference of other ions. If you really want to study the specific properties of a combination of silver ions and permanganate ions, then you always have the option to dissolve for example silver nitrate and potassium permanganate in a single solution. The potassium and nitrate ions, will be just spectator ions in most of your experiments.
So as rules of thumb:
Acids and bases
Many experiments require the use of an acid or a base. The ideal situation would be to have an acid, which is strong and which has no other property, besides being acidic. The same holds for bases.
Unfortunately there is not a single acid, which is just acidic and has no other relevant properties. For this reason, even a simple home lab should have a choice between strong acids. If no suitable strong acids are available, many interesting experiments simply are not possible. If possible, try to obtain the following acids:
Hydrochloric acid has slight reducing properties, which only becomes a problem in combination with strong oxidizers like permanganate and persulfate. For many experiments this is not a problem. The chloride anion, however, also has quite strong coordinating properties. With many metals (e.g. copper, cobalt, iron) it forms colored complexes, which may affect the outcome of certain experiments.
Nitric acid is a strong oxidizer when it is at moderate to high concentration. Dilute nitric acid (approximately 1 M or less), however, is a very good approximation of the ideal acid without other properties. Nitrate ion is only very weakly coordinating in most situations. So, dilute nitric acid is a good choice for many experiments, where hydrochloric acid causes interference from the chloride ions.
For most chemical experiments, requiring an acidic environment, sulphuric acid probably is the most versatile. This acid is non-reducing and non-oxidizing, even at fairly high concentration and in most situations, the sulfate counter ion also is non-coordinating. Only with some metals, such as lead, silver, barium and calcium, the use of sulphuric acid may be a problem, due to formation of a precipitate of the metal salt. When sulphuric acid needs to be diluted, always add acid to water slowly, while constantly stirring, never pour water on the acid.
For many experiments, a relatively safe and suitable alternative for dilute sulphuric acid is sodium bisulfate, NaHSO4. The sodium ions and extra sulfate ions do not interfere in most experiments. It is strongly advised to buy a pound or two of this compound, which is available as pH-minus for swimming pools. It can also be ordered and shipped from many photography raw chemical suppliers.
With bases, the situation is more simple. Either sodium hydroxide or potassium hydroxide is suitable. Both of these give the strong base OH –. The cations Na+ or K+ generally do not interfere. Both bases are soluble in water very well. For the majority of the chemical experiments, requiring a strong base, the drain openers, based on 98 - 99% NaOH are a suitable and cheap source of a strong base.
Many interesting experiments involve the oxidation of one or more compounds. It is best to have a set of oxidizers, ranging from mildly oxidizing to strongly oxidizing. It is best if both the oxidizer and the reduced species are colorless in aqueous solution, otherwise the color of the oxidizer or its reduced species may mask the results of the experiment or at least the color will interfere. Oxidizers like potassium permanganate and potassium dichromate, which are quite common, are not suitable as the main oxidizers for a home lab, due to their strong colors. The following compounds constitute a reasonable set of suitable oxidizers:
In a starting home lab, it is sufficient to have these oxidizers. Potassium nitrate and potassium perchlorate are not suitable as oxidizers in aqueous chemistry, due to the very low speed of the reactions of these compounds at any pH larger than 0. For dry chemical experiments or pyrotechnics experiments, these oxidizers, however can be quite useful.
For reductors, it also is best if they are colorless and the reaction product also is colorless. In aqueous chemistry, the number of strong soluble and colorless reductors is quite limited. Most reductors, mentioned here, are only mild reductors. The only strong reductor is zinc, which however is not colorless and soluble, but which does have a colorless and soluble reaction product.
Besides the reductors, mentioned above, there are a few more, such as magnesium and aluminium. Especially magnesium is too reactive to be useful as aqueous reductor. In acidic media it quickly reacts with the acid, forming hydrogen gas, such that only a small amount of reductive power is made available for the reaction with any compound in the water. Other strong reductors, such as photographic developers also are not suitable. The reaction products often are intensely colored polymeric species, which also are strongly coordinating to most metal ions.
There is a strong reductor, suitable for aqueous chemistry at high pH. This is sodium borohydride. This compound, however, is quite expensive and not without risk. This is not a compound to start with, but for the more experienced home chemist, this may be a valuable addition to the home lab. It is available from a few raw chemical photography suppliers.
The halogens chlorine, bromine and iodine are an interesting group of elements to experiment with. These elements form interesting colorful gaseous compounds at low to medium temperatures and are quite reactive. With an oxidizer like bleach or hydrogen peroxide, halogens can be prepared easily at the home.
Interesting compounds of the halogens are:
Elementary chlorine and bromine can be prepared, but should not be stored. Iodine can be stored well, but it is wise to store this in a small tightly capped container, wrapped in tissue paper, which is placed in a larger tightly capped container. The problem with iodine is its volatility. Iodine vapor stains everything with a strong brown color. Hence the need to store this in a double container with tissue paper around the smaller container.
Iodine and its compounds are quite expensive. However, you only need at most a few tens of grams of these compounds. Bromides are fairly cheap and chlorine compounds also are quite cheap.
Transition metals and some ligands
The transition metals are among the most interesting for the amateur chemist. These metals form many colorful compounds and can be used in a large number of interesting experiments. Even up to now, there still is a lot to discover about the chemistry of these metals, also for the home chemist. For a starting home chemist, the following compounds are definitely worth the cost:
All compounds, mentioned above, can be obtained fairly easily in most parts of the world. For the more advanced home chemist, the following can be added to this list.
The transition metals have an interesting coordination chemistry and redox chemistry. Interesting ligands to start with for the transition metals are:
An interesting aspect of coordination chemistry is the relation between pH and the complexes formed. With the set of chemicals, mentioned in this section on transition metals, there is a really endless variation of possibilities, which can be explored deeply.
Finally, there are some chemicals, which are a nice addition to the home lab at low cost. These can be used for precipitation reactions, redox reactions and sometimes also in coordination reactions. When starting a home lab, it is suggested to have these chemicals available soon.