11 chem, week 13 - Acid with some Sweet Base

Hey y'all, it's Liam again.  Let's go straight into it!

These poor guys.  They're probably gonna get fired now.

Starting the next module, I found it was on something we'd already touched on in the course: acids and bases.  However, we went more in-depth this time, talking about strong and weak acids and bases.  For example, a strong acids is very willing to give up its electrons (maybe too willing; what's it hiding?), whereas a weak acid likes its electrons, and will only part with a few.  The same applies to bases, except that with bases the strong ones like to take a lot of electrons, and the weak ones only take a few.  In addition, concentration was discussed in the following way: "If you were given the choice between drinking a solution of 0.1% hydrochloric acid [the main part of gastric acid, or our digestive fluids] (a strong acid) to 70% acetic acid [the main acid in vinegar] (a weak acid), which would you choose and why?"  Coming on a bit strong there, forcing me to drink acid, but the module also raised an interesting question: what does 70% acetic acid mean?  As it likely doesn't mean the strength of it (it had to be mentioned that acetic acid was weak), I concluded that the percentage referred to concentration (I did watch the provided video but, alas, I was still confused). Essentially, it means that only 70% of the solution is actually acetic acid.

After this fun thought experiment (which, by the way, was prefaced with DO NOT ACTUALLY DRINK ACIDS) I was presented with a PhET applet, and as per usual it was fun to go through.  It was about strong and weak acids and bases, and I learned two main things from it:

• Weak acids/bases will never be as strong as their stronger acid/base counterpart
• Both strong acids AND strong bases are very good conductors, presumably because of the higher number amount of ions floating around

The next section comprises notes taken on five separate videos.  The first two were about the differences between weak and strong acids, and weak and strong bases, respectively:

• Strong acid: ionizes extremely well.  Most, if not all, acid molecules are ionized
• HCl (aq) + H2O (L)  → Cl- (aq) + H3O+ (aq)
• H2SO4 (aq) + 2H2O (L)  → SO42- (aq) + 2H3O+ (aq)
• Weak acid: ionizes poorly.  Most acid molecules are not ionized
• HC2H3O2 (aq) + H2O (L)  → C2H3O2 (aq) + H3O+ (aq)
• Most of the acid remains in the protonated (HC2H3O2) form; only a small amount becomes acetate ions

Overall, strong acids have lower pH levels, are better conductors, and ionize far more than weak acids

• Strong bases: dissociates 100% in aqueous solution
• Typically contain a group 1 cation and hydroxide ions
• NaOH (s)  → Na+ (aq) + OH- (aq)
• Weak base: does NOT dissociate 100% in aqueous solution
• Either insoluble hydroxide compounds that dissociate very little (as mentioned below) or other compounds that ionize (react with) water to produce more hydroxide ions

Could be due to solubility (as in the example of Ca(OH)2)

The next video discussed the Bronsted-Lowry theory. This lovely hypothesis defines acids and bases based on what they do, not what they are (pretty inspiring stuff, right?):

Acids are proton (H+) donors (in the equation HCL + H2O → H3O+ + Cl-, HCl donates the proton)

Bases are proton (H+) acceptors (in the equation NH3 + H2O → NH4+ + OH-, NH3 accepts the proton)

In EACH REACTION there is both an ACID and a BASE

• HCl + H2O  → Cl- + H3O+
• Acid is HCl, base is H2O (HCl gives it away, H2O takes it)
• Backwards, Cl- is conjugate base (accepts the proton) and H3O+ is conjugate acid (gives away proton)

Water is both amphiprotic (it can donate or accept H+ ions) and/or amphoteric (can act as acid or base)

Another amphiprotic/amphoteric ion is the bicarbonate ion (HCO3- (aq))

The last video was all about neutralization reactions. These types of reactions are between an acid and a base, and they always produce water and some sort of salt.

Thank you for reading, hopefully you found some joy with this nice peak into my chemistrical life (Is that a word?  I don't think it's a word) and I hope to keep providing said entertainment until we finish our little journey together!

 - L