Naming Acids Tutorial

1. Naming Acids Tutorial Acids are a group of compounds that, when dissolved in water, all have very similar properties. They all have low pH values; they all react with metals; they all dissolve carbonate compounds… And they all taste sour! Here is a list of some common acids: HCl, H2SO4, HNO3, HC2H3O2, H2CO3, HF, H3PO4. What do you notice about all these compounds? Hopefully you noticed that they all start with “H.” In solution, these H’s break off as H+ ions, and it is these hydrogen ions that are responsible for making the solution behave as an acid.

2. Naming Acids Tutorial • But how are acids named? • Actually, the process is quite simple… if you already know how to name regular ionic compounds. • All you do is make two easy changes to the name: • Drop the word “hydrogen” in the beginning and replace it with the word “acid” at the end. • Change the suffix (ending) of the negative ion: • If it ends in “–ate,” change it to “-ic.” • If it ends in “–ite,” change it to “-ous.” • If it ends in “–ide,” change it to “hydro- -ic.” • That’s it! (Write these steps down in your notes right now, so you will have them to refer to for the next slides.)

3. Naming Acids Tutorial Let’s try a few examples: What would be the regular ionic name for HNO3? Hopefully you knew the answer is: Now change the “hydrogen” in the beginning to “acid” at the end. Then change the “-ate” ending to “-ic.” Thus the correct acid name is “nitric acid.” Nitric acid is a very strong, corrosive acid that is capable of dissolving copper! acid hydrogen nitric nitrate

4. Naming Acids Tutorial Let’s try a few examples: What would be the regular ionic name for HClO4? Hopefully you knew the answer is: Change the “hydrogen” in the beginning to “acid” at the end. Then change the “-ate” ending to “-ic.” Thus the correct acid name is “perchloric acid.” Perchloric acid is even stronger than nitric acid, and it is used in the production of rocket fuel. hydrogen acid perchlorate perchloric

5. Naming Acids Tutorial Let’s try another example: What would be the regular ionic name for HBrO2? Hopefully you knew the answer: Change the “hydrogen” in the beginning to “acid” at the end. Then change the “-ite” ending to “-ous.” Thus the correct acid name is “bromous acid.” Although we can name this acid, chemists have never been able to actually isolate bromous acid. It is just too unstable to exist! hydrogen acid bromite bromous

6. Naming Acids Tutorial Let’s try another example: What would be the regular ionic name for HClO? Hopefully you knew the answer: Change the “hydrogen” in the beginning to “acid” at the end. Then change the “-ite” ending to “-ous.” Thus the correct acid name is “hypochlorous acid.” Because it is so effective at killing bacteria, hypochlorous acid is used as a disinfectant in swimming pools. acid hypochlorous hydrogen hypochlorite

7. Naming Acids Tutorial Let’s try another example: What would be the regular ionic name for HF? Hopefully you knew the answer: Change the “hydrogen” in the beginning to “acid” at the end. Then change the “-ide” ending to “hydro- -ic.” Thus the correct acid name is “hydrofluoric acid.” HF is capable of dissolving glass – or etching it: Designs like the one at right are made by placing tape over portions of the glass, then dipping it in a solution of hydrofluoric acid. The exposed areas get that frosted look, while the taped-over parts remain clear. acid hydrofluoric hydrogen fluoride

8. Naming Acids Tutorial • Now it’s your turn. Try naming the following acids: • “(aq)” stands for aqueous, and it means that these compounds are dissolved in water. • HBrO4(aq) • HBr(aq) • HC2H3O2(aq) • HNO2(aq) • HIO(aq) • H2CO3(aq) • HCN(aq) • H2Cr2O7(aq) • H3PO3(aq) • H2SO4(aq)

9. Naming Acids Tutorial • In case you were having difficulty, here are their regular ionic names: • HBrO4(aq) • HBr(aq) • HC2H3O2(aq) • HNO2(aq) • HIO(aq) • H2CO3(aq) • HCN(aq) • H2Cr2O7(aq) • H3PO3(aq) • H2SO4(aq) hydrogen perbromate hydrogen bromide hydrogen acetate hydrogen nitrite hydrogen hypoiodite hydrogen carbonate hydrogen cyanide hydrogen dichromate hydrogen phosphite hydrogen sulfate

10. Naming Acids Tutorial • And so these would be the correct acid names: • HBrO4(aq) • HBr(aq) • HC2H3O2(aq) • HNO2(aq) • HIO(aq) • H2CO3(aq) • HCN(aq) • H2Cr2O7(aq) • H3PO3(aq) • H2SO4(aq) perbromic acid hydrobromic acid acetic acid (AKA: vinegar!) nitrous acid hypoiodous acid carbonic acid hydrocyanic acid dichromic acid phosphorous acid sulfuric acid About the last two acids: You probably thought they would be “phosphous acid” and “sulfic acid,” but they are not. Perhaps for example SO42- used to be called “sulfurate,” and then it got shortened to “sulfate,” but the acid name stayed “sulfuric” – who knows???

11. Naming Acids Tutorial • Now try going the other way: Write the correct formulas for the following five acids • Chromic acid • Hydroiodic acid • Boric acid • Citric acid (citrate = C6H5O73-) • Permanganic acid

12. Naming Acids Tutorial • These are the answers you should have come up with: • Chromic acid • Hydroiodic acid • Boric acid • Citric acid • Permanganic acid • These are the answers you should have come up with: • Chromic acid H2CrO4 • Hydroiodic acid HI (it’s a friendly acid!) • Boric acid H3BO3 • Citric acid H3C6H5O7 • Permanganic acid HMnO4 Notice that it’s not only important to write down the correct formula for the ions, but it’s also important to balance the charges. For example, because H1+ has a 1+ charge and CrO42- has a 2- charge, it took 2 H’s to balance the charge on the one CrO4. Hence: H2CrO4