Rob Lederer: Now acids are solutions that are kind of molecular like an ionic; ionic in that they dissociate to form ions and solution, molecular like because they look like they have molecular formulas but they all have in them hydrogen, which then ionizes in solution, dissociates breaks down into ions and the H-positive causes the acidity of a solution. Now what are -- that's a definition of an acid, but not certainly a property. So what's the property of an acid? Well, they are electrolytes, they conduct an electrical current, their pH is less than 7.
So if you got a solution that's got a pH less than 7, you have yourself and acid, and it has to be an electrolyte. They turn blue litmus paper red; blue litmus paper in acid turns red; blue, acid, red; BAR. When you go to the bar, you drink acid. I don't know, it's just a way to remember it I guess. So the thing - well, actually if you went to a bar to have coke, you dip a piece of litmus paper into the fizzy substance, that's carbonic acid in there that cause the fizz. That's carbon-dioxide dissolved in water, carbonic acid.
So litmus paper in a coke will turn from blue to red. Now acids also react with active metals to form hydrogen gas. You know in that redox chart, that half reaction that has hydrogen ion, an H-positive, it's a cross from 0.00 volts; it's the standard by which all the others are compared. That hydrogen half reaction in this position here reacting with any metal that is a reducing agent, that is below this hydrogen ion will react spontaneously with that hydrogen ion and the metal will break down and the hydrogen will turn into hydrogen gas. So that's a property of acids as well; they taste sour. So when you take a piece of lemon which has citric acid in it, that's sour, alright. If your autonomic nervous system works pretty well, you're probably just salivating right now thinking about biting into a lemon. So when you do that, you'll find a very sour taste. Anything that tastes sour is because it produces an acid inside your mouth, absolutely. So acids taste sour.
Now here are some examples of acids. There is nitric acid, hydriodic acid, hydrochloric acid, sulfuric acid, that's perchloric acid and hydrobromic acid; six; one, two, three, four, five, six strong acids. Strong acids are strong electrolytes; that's why they are called strong. They'll break down in solution 100% and really light up a light ball, they are highly conductive, but there are weak acids too. For instance, acidic acid which is vinegar, I'm going to drink any lot for you. That acidic acid will actually conduct an electrical current but quiet poorly. So we say it's weak in terms of its conductivity, so we call it a weak acid. Those are the properties of acids.
Bases are solutions that are electrolytes as well but the pH is greater than 7. So red litmus paper turns blue when you put into a base; red litmus paper, base, blue, RBB: rhythm and blues band, because in a rhythm and blues band, when the instruments you play is a base, okay I tried. Now they feel slippery to the touch, that's what a base does. So like salt, salt actually has hydroxide in it and it feels like a base. You know lye, that's salt and that's made from sodium hydroxide. So they also taste bitter. So if you take a little bit of baking soda and then you have a -- okay see that's a base face there, alright. There is acid you saw that before and bases, so those are facial definitions if you will of acids and bases or at least properties. Now examples of bases could be things like sodium hydroxide, potassium hydroxide, then sodium carbonate, sodium bicarbonate, that was the baking soda you just tasted, and then there is potassium sulphate.
Here are some ones that might be tricky in terms of how they look, but don't get them confused with each other, check this out. So look at these formulas; CH3OH, Li2CO3, C6H5COOH, and I say to you, which ones are base? Now some students have learned out, well, when I see that OH, I am thinking base; you got be so careful. CH3OH is actually methanol and we show that before into the molecular compounds, that's not a base, a pH of 7 is what that would have in a solution. That just because have an OH doesn't mean that it's a base, that's an organic type of hydroxyl group that's attached to CH3.
So when you see organic, which is carbon and hydrogen or hydrocarbon with an OH tag at the end, that's an alcohol, don't treat it as a base, it's not. Li2CO3 is actually a base, because carbonate ion is a base, you'll see that later. So not everything that has OH in it is going to be a base and sometimes things that don't have an OH in it are bases, but I'll show you why in a second they are. Now see this one, C6H5COOH is called benzoic acid, because when you see this hydrocarbon formula but then you see COOH, if you see COOH, you got yourself an organic acid. So COOH will tell you acid. Hydroxyl group on a hydrocarbon though, that's molecular and that is actually a base, that's coming up.