Achieve Week 10 - Question 1

[Shiley_David_1D]

Hello all!

I am slightly confused about how to identify strong and weak acids. The solution to the question refers to a list of strong acids being used to determine acid strength, but we will likely not have that list on the Final, so I was wondering how we are supposed to determine strength without it? For instance, the solution discusses how strong bases typically contain a metal cation and OH, and weak bases tend to contain nitrogen, so is there any similar general rules like that for acids?

Thank you for your help!

[Anna Furton]

Strong acids typically contain a halogen (but not F) and an H, so that includes: HCl, HBr, and HI.

Other strong acids consist of a negatively charged molecule that contains an O bonding with an H (oxyacids), so that includes: H2SO4, HNO3, HClO4, and HClO3.

While there are these patterns as I stated above, honestly the easiest way to learn them is probably just to memorize the list of strong acids. The ones we need to know are the ones stated above, and if the acid is not one of these seven, we would consider it a weak acid.

[loganchun]

Hi, you would have to memorize these strong acids. To memorize, use the mnemonic SO I BRought NO CLean CLOthes where the capital letters in each word represent a strong acid. SO corresponds to H2SO4, I corresponds to HI, BR corresponds to HBr, NO corresponds to HNO3, CL corresponds to HCl, and CLO corresponds to HClO3 and HClO4. Weak acids are anything else other than the strong acids and typically start with H or ends in -COOH.