Chemistry sets from brands like Thames Kosmos, Scientific Explorer and Powertech provide children with hours of educational entertainment. The great thing about these sets is they provide all the chemicals and materials required to conduct the experiments. But what do you do when the chemicals have all been used?

Walmart seems to have just about everything but have you ever found the chemicals aisle? Not only are chemicals hard to find but who even knows what to buy? This article explains the difference between 3 grades of chemicals so you can know the right chemicals for your next school experiment, homework assignment or science fair project.

Chemistry sets can awaken an interest in chemistry and the physical world, setting children on a path to a future career. Even the most basic chemistry sets are filled with experiments that will peak and keep the interest of children who already have a basic scientific interest or knowledge, or those who are absolute beginners. Chemistry experiments are designed to teach things like air pressure and water tension, and how everyday things function. Some of the experiments work with benign objects, while others require chemicals.

Not all the experiments found in chemistry sets like the Thames Kosmos series require the use of chemicals. For those that do, it’s good to know what you’re working with, and what your choices are when you need to purchase chemicals.

Most chemicals are graded, the grade representing the purity of the chemical. A chemical with a higher grade has fewer impurities, or other chemicals, such as metals and water, than those with a lower grade. The cost of chemicals is in keeping with its grade: a higher grade is more expensive than lower grades.

Although there are several different protocols for grading chemicals, there are three basic grades that are the most common and most likely to be used. They are, from highest to lowest, reagent grade, laboratory grade, and technical grade.

Reagent grade, also known as ACS, is the highest chemical grade there is, meaning it is the most pure. It meets or exceeds American Chemical Society standards. Chemicals graded as reagent grade can be used in all situations, from scientific to manufacturing. It is the only chemical grade that can be used in biological experiments.

Laboratory grade chemicals, which may also be referred to as lab, are less pure than reagent grade chemicals, but are still of a fairly high purity. These chemicals would not be pure enough to use in medical or food products, but they are usually more than adequate for science fair projects.

Technical grade chemicals are also called industrial grade, and are the least pure chemicals. Chemicals of this grade are typically used in industrial or commercial applications, but may be adequate for some science fair projects. These chemicals are not acceptable for use in food or medicinal purposes.

If your experiment has stringent requirements for chemical purity, your best bet would be purchasing from a chemical supply house where you can be assured of the grade of chemical you are purchasing. If you are unsure of what grade is needed for a particular experiment, laboratory grade is a safe choice.

So now that you have a handle on that, where do you go to find the chemicals you need? You don’t have to buy chemistry sets to get more chemicals. You can actually purchase just the chemicals at various stores (hardware store, drug store, even the grocery store) rather than a chemical supply house. However, before you get excited about that, there is a problem. When you buy from these types of stores, the chemicals are unlikely to be graded and may contain an unacceptable level of impurities for the experiment being performed.

Now you can buy the right chemical with confidence that it will get the job done. Having the proper chemicals allows you to successfully conduct experiments. It also allows you to replenish the supply of chemicals in your old Thames Kosmos chemistry sets so you can blow the dust off of the set and put it back to good use.

Joe Kanooga is a father of two kids, a successful business owner and the author of numerous articles about Thames Kosmos. Visit learningthings.com to learn more.