Wolfram|Alpha is a great resource for learning about chemical reactions. We recently rolled out a brand new interface that allows you to easily search through our large database of reactions and explore classes of chemical reactions (such as combustion or oxidation reactions). And we also introduced new Step-by-step functionality to illustrate how to balance chemical reactions.
To demonstrate how Wolfram|Alpha may benefit you, imagine a chemistry lab where the experiment is to combust ethanol, creating a spectacular fireball. While this is certainly an exciting application of chemistry, it brings up several important questions: What does it mean to combust ethanol? What exactly is ethanol? And how much energy was actually released in that fireball? Wolfram|Alpha to the rescue.
Our revised chemical reaction interface can answer these questions and many more. When you query combustion of ethanol, Wolfram|Alpha’s database of combustion reactions is searched with ethanol as a reactant. (In the chemical reaction hydrogen + oxygen -> water, the reactants are hydrogen and oxygen, while the product is water.) Now let’s do some chemistry!
In this case, there is only one reaction, and it is indeed the one we’re looking for. Clicking the “Sample reactions” box takes you to a page where you can view the reagents through their formulas, structure diagrams, or chemical names, along with the reaction thermodynamics (from which you can calculate the energy released by the ethanol fireball).
The Step-by-step button teaches Wolfram|Alpha Pro users how to balance any chemical reaction, no matter how complicated (if you want a challenge, try balancing CaSO4 + CH4 + CO2 -> CaCO3 + S + H2O without peeking). Note that Wolfram|Alpha will balance both the atoms and the charge on both sides of a reaction—so telling us that H+ -> H2 is not being balanced does not count (since it actually cannot be balanced). But here’s a secret: We allow you to write the formula of any molecule with no restriction, so you can go wild with your queries.
If you query a balanceable chemical reaction (using the form “reactant1 + reactant2 + … -> product1 + product2 + …”), you will obtain the reaction’s page that shows you its balanced equation, chemical structures, chemical names, thermodynamics, equilibrium constant, and chemical properties. If you type in an unbalanceable reaction by either specifying only reactants (“reactant1 + reactant2 + … ->”), specifying only products (“->product1 + product2 + …”), or specifying both reactants and products that are unbalanceable, you are searching Wolfram|Alpha’s database for all reactions that contain reactant1, reactant2… as reactants and product1, product2… as products.
Let’s return to the combustion of ethanol example. If you know that the combustion of ethanol must be of the form C2H5OH + O2 -> H2O+ CO2, you can type this in directly and get the reaction’s page. However, the power of our new interface comes from being able to search for a reaction without knowing the exact reactants and products. For example, suppose you know that iron turns to rust, but not how this happens, or for that matter what the chemical formula for rust is. Querying iron -> rust will lead you to your desired reaction while teaching you that rust is iron oxide.
(Alternatively, you could have queried oxidation of iron and gotten the same result. Knowing some basic chemistry never hurts!)
A word of warning: If you type chemical reactions using chemical names (hydrogen + oxygen ->) rather than chemical formulas (H2 + O2 ->), there is some ambiguity. For example, “hydrogen” may refer to the chemical compound H2, the element H, or the ion H+. Inside of chemical reactions, Wolfram|Alpha will by default assume the most common form found in nature (in this case, H2), though you can always correct this interpretation using the “Assuming” section at the top of the result. This functionality may lead to seemingly incorrect search results if you specifically want ions.
For example, searching for hydrogen -> hydronium will not find any chemical reactions, even though H+(hydrogen) + H2O (water) -> H3O+ (hydronium) is a reaction in our database. To find it, you can either choose “Assuming ‘hydrogen’ is an ion,” enter the query hydrogen (ion) -> hydronium, or enter the unambiguous chemical formula H+ -> H3O+. Further, note that some chemical formulas may represent multiple chemicals (for example, C6H6 has several isomers); in such cases we again assume the most prevalent molecule found in nature. Thus, C6H6 -> defaults to the reactant benzene.
In addition to narrowing your search using reactants and products, another new feature is the ability to search through chemical reaction classes. As previously mentioned, combustion of ethanol and oxidation of iron search for the reactant ethanol in our combustion reaction database and for the reactant iron in our oxidation reaction database, respectively. Wolfram|Alpha has many types of chemical reactions, and the full list can be viewed using the query chemical reaction classes.
Even chemistry whizzes may not remember each of these types of chemical reactions. To refresh your memory, you can click any of these reaction classes to bring up a list of sample reactions—for example, you can look up some redox reactions.
Now suppose you want to make sodium acetate, also known as hot ice (also known as the coolest material ever… just wait and see). Querying -> sodium acetate shows a list of potential reactions. In case you’re not familiar with some of these chemicals, there is a helpful “Show formulas” button that shows both the chemical formulas and the names.
The third entry looks particularly enticing, since you probably have all of these ingredients in your home already. Acetic acid is the main component in vinegar (aside from water), while sodium bicarbonate is baking soda. Let’s do some science! Adding the two in a beaker and heating it up will yield the sodium acetate and water, along with carbon dioxide gas. Since the gas will float away, you can then boil off the water and obtain sodium acetate. That was quite helpful, but the fun does not end there. Place the sodium acetate in a refrigerator to chill for a while.
Returning from your hardcore lab experience, click the third sodium acetate reaction to bring up a slew of information about it. At the bottom, Wolfram|Alpha gives details about the reactants and products. For example, we find that sodium acetate is a solid at room temperature.
A refrigerator (which usually has a temperature less then 10°C) is certainly cooler then STP (standard temperature and pressure, or 20°C). But if you perform the experiment above, you will find that the sodium acetate mixture in the refrigerator is still a liquid; thus, you have actually supercooled liquid sodium acetate to below its freezing point! Aside from being super cool, this mixture has the remarkable property that it will solidify when disturbed. Poking the mixture will quickly turn it into ice, while pouring the mixture creates some fantastic sculptures. To top it all off, this crystallization from liquid to ice is an exothermic process, so that the resulting sodium acetate ice block will be warm!
We encourage you to explore the new interface. Or if you want to learn more on how to balance even the trickiest chemical reactions, try the latest addition to our ever expanding Step-by-step functionality. And yes, if you burn with the desire to do so, you can learn more about the combustion of ethanol!