The strengths and weaknesses of acids and bases - George Zaidan and Charles Morton
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0:07 - 0:09Acids and bases are everywhere.
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0:09 - 0:10They're used to make foods,
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0:10 - 0:12soaps and detergents,
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0:12 - 0:12fertilizers,
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0:12 - 0:13explosives,
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0:13 - 0:14dyes,
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0:14 - 0:15plastics,
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0:15 - 0:15pesticides,
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0:15 - 0:17even paper.
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0:17 - 0:18Our stomachs are very acidic.
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0:18 - 0:20Our blood is slightly basic.
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0:20 - 0:23Our proteins are made up of amino acids,
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0:23 - 0:25and the letters in our genetic code,
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0:25 - 0:27those As, Ts, Cs, and Gs,
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0:27 - 0:29are all bases.
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0:29 - 0:30You were probably taught
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0:30 - 0:31how acids and bases behave
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0:31 - 0:32on the molecular level.
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0:32 - 0:34You were probably never taught
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0:34 - 0:35that a long time ago,
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0:35 - 0:37like ancient Greek ago,
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0:37 - 0:40before anyone knew about atoms or molecules,
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0:40 - 0:41acids and bases were defined
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0:41 - 0:43by how they behaved.
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0:43 - 0:46Acids tasted sour and corroded metal.
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0:46 - 0:48Bases felt slippery
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0:48 - 0:51and could somehow counteract acids.
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0:52 - 0:55When molecules dissolved in water interact,
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0:55 - 0:57they are exchanging two main currencies
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0:57 - 0:58with their surroundings:
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0:58 - 1:01protons, also known as hydrogen ions,
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1:01 - 1:02and electrons.
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1:02 - 1:05Depending on how a molecule is composed or shaped,
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1:05 - 1:08it may be willing to donate or accept
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1:08 - 1:09either protons or electrons
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1:09 - 1:11with some other community member.
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1:11 - 1:14And some molecules are far more aggressive than others
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1:14 - 1:18when it comes to donating or accepting either currency.
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1:18 - 1:20Remember that protons are positively charged
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1:20 - 1:22and electrons are negatively charged.
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1:22 - 1:25So, if a molecule is willing to give up a proton,
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1:25 - 1:26that's not too different
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1:26 - 1:29from it being willing to accept an electron --
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1:29 - 1:32either way it's becoming more negatively charged.
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1:32 - 1:34Other molecules are willing to accept a proton
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1:34 - 1:36or give up an electron.
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1:36 - 1:39These are becoming more positively charged.
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1:39 - 1:41Some substances are so aggressive
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1:41 - 1:43about donating their protons
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1:43 - 1:44that when they get a chance,
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1:44 - 1:46all of the molecules in a sample
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1:46 - 1:47will dump a proton,
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1:47 - 1:48sometimes more than one,
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1:48 - 1:50to the surrounding water molecules.
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1:50 - 1:53We call these strong acids.
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1:53 - 1:55Meanwhile, some compounds are so ready
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1:55 - 1:56to accept a proton
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1:56 - 1:57that they won't wait around,
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1:57 - 1:59they'll just rip one off water,
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1:59 - 2:01which usually has two protons
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2:01 - 2:03but is generous enough to hang out with just one.
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2:03 - 2:06We call these strong bases.
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2:06 - 2:08Other acids and bases are not so strong.
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2:08 - 2:11They may donate just a few of their protons to water
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2:11 - 2:14or accept just a few protons from water,
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2:14 - 2:17but most of their molecules stay exactly the same.
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2:17 - 2:18If left alone in water,
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2:18 - 2:20they'll reach some equilibrium point
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2:20 - 2:22where maybe only one out of a hundred
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2:22 - 2:24or one out of ten thousand of their molecules
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2:24 - 2:26has exchanged currency with water.
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2:26 - 2:28As you might guess,
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2:28 - 2:30we label these acids and bases weak,
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2:30 - 2:31but in the common sense of the word,
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2:31 - 2:33they're not weak.
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2:33 - 2:34The vinegar in your salad dressing
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2:34 - 2:36that you can smell from across the room,
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2:36 - 2:38that is a weak acid.
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2:38 - 2:39The ammonia you spray on glass
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2:39 - 2:41for a streak-free shine,
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2:41 - 2:42that is a weak base.
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2:42 - 2:45So, it doesn't take much to be an active player
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2:45 - 2:47in the chemical economy.
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2:48 - 2:50Most acid-base chemistry takes place in water,
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2:50 - 2:53which can act as either an acid or a base,
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2:53 - 2:55accepting deposits and enabling withdrawals
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2:55 - 2:58like a 24-hour molecular ATM.
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2:58 - 3:00And when a proton-deposit customer,
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3:00 - 3:01that's an acid,
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3:01 - 3:04and a proton-withdrawal customer,
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3:04 - 3:04the base,
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3:04 - 3:06shop at the same time,
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3:06 - 3:08their net effect on water's account
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3:08 - 3:09may cancel out,
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3:09 - 3:12and we call this neutralization.
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3:12 - 3:14Now, certain molecules can behave
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3:14 - 3:16as acids or bases without water,
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3:16 - 3:17but that's another story.
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3:17 - 3:19Let's end by saluting water
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3:19 - 3:21as the resilient and fair banker
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3:21 - 3:23for acids and bases.
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3:23 - 3:24It's always open for business,
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3:24 - 3:25doesn't charge interest,
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3:25 - 3:28and will never foreclose on your molecules,
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3:28 - 3:30which is more than I can say for [bleep].
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3:31 - 3:32Waah-waah.
- Title:
- The strengths and weaknesses of acids and bases - George Zaidan and Charles Morton
- Description:
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View full lesson: http://ed.ted.com/lessons/the-strengths-and-weaknesses-of-acids-and-bases-george-zaidan-and-charles-morton
Vinegar may have a powerful smell, but did you know it's actually a weak acid? In the chemical economy, acids actively give away their protons while bases actively collect them -- but some more aggressively than others. George Zaidan and Charles Morton use the currency of subatomic particles to explain this unseen exchange.
Lesson by George Zaidan and Charles Morton, animation by Karrot Animation
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 03:48
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