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What’s an ACID and what’s a BASE? How can you tell them apart?

What’s an ACID and what’s a BASE? How can you tell them apart? Time to take out some paper, take a few notes, tomorrow we will venture to the back and “play” chemistry with goggles on. We’ll also find out what happens when we mix them together!.

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What’s an ACID and what’s a BASE? How can you tell them apart?

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  1. What’s an ACID and what’s a BASE? How can you tell them apart? Time to take out some paper, take a few notes, tomorrow we will venture to the back and “play” chemistry with goggles on. We’ll also find out what happens when we mix them together!

  2. According to Svante Arrhenius, the man who won the Noble Prize for explaining what acids and bases are, and how they work… Acids are solutions that have excess hydrogen ions in them, which come from compounds with hydrogen in them, like: HCl, H2SO4, and HNO3. Even though these are molecular compounds, and they ARE NOT ionic, when these kinds of compounds go into water, the hydrogens ionize like salts do, this way: HCl + H2O H+1(AQ) and Cl-1 (AQ) H2SO4+ H2O H+1(AQ) + H+1(AQ) and SO4-2(AQ) HNO3+ H2O H+1(AQ) and NO3-1(AQ)

  3. Arrhenius said: when a solution has lots of Hydrogen Ions (H+1) in solution it is acidic, or it is an ACID. The more hydrogen ions in solution, the stronger the acid is. Some acids are weak, like acetic acid. We eat Acetic Acid, it’s called vinegar. It DOES NOT have a lot of hydrogen ions, it’s an acid, but because it’s weak it cannot hurt our skin. In fact, it feels sort of “snappy” in our mouths. Hydrochloric acid is MUCH STRONGER, and although chemically it’s the same as acetic acid if we put it onto our salad greens & tomatoes, they might dissolve.

  4. Acids are strong or weak depending upon how many Hydrogen Ions are in solution. There are 2 reasons to have lots, or few. • Some acids, like HCl, go into water and almost every single molecule dissociates into ions like this: • HCl + H2O H+1(AQ) and Cl-1 (AQ) • A million HCl Molecules would probably do this: • 1,000,000 HCl + H2O 999,999 H+1(AQ) + 999,999 Cl-1 (AQ) + 1 HCl(AQ) Almost every single molecule comes apart, making another H+1 ion. It dissociates very well.

  5. Some, like vinegar (acetic acid) don’t really come apart too well. So if you put say 1,000,000 molecules into water, this is what happens: • 1,000,000 HC2H3O2 + H2O • 100,000 H+1 + 100,000 C2H3O2-1(AQ) + 900,000 HC2H3O2(AQ) molecules in solution • Most of these molecules DO NOT DISSOCIATE, so there are much LESS H+1 ions in solution.

  6. Strong Acids dissociate well, and have LOTS of H+1 ions in solution. Weak Acids DO NOT dissociate well, they have LESS H+1 ions in solution. Strong acids can be concentrated (super lots of H+1 ions, dangerous to skin) or they can be dilute (almost all molecules dissociate but not many molecules so not many H+1 ions. Weak acids can be concentrated but will not be strong anyway because they just do not dissociate well. There will be lots of dissolved molecules that DO NOT come apart. Weak acids can be dilute too, which means few molecules go into the water and very few come apart to form H+1.

  7. BASES are the chemical opposites of acids. They have lots of HYDROXIDE ions in solution, which are OH-1 ions. Examples include Sodium hydroxide + potassium hydroxide, These are all salts, and in water they dissociate very well.

  8. NaOH + H2O Na+1(AQ) + OH-1(AQ) KOH + H2O K+1(AQ)+ OH-1(AQ) Almost ALL of these compounds dissociate totally, they are like the strong acids. The more hydroxide ions in solution, the stronger the base. The less hydroxide ions in solution, the weaker the base.

  9. How strong is your acid? We use something called the pH scale (NOT the PH or Ph scale, OK?) The pH scale stands sort of for “proportion of H+1 ions in solution, using a logarithm scale which is a negative power of ten – don’t worry!) The scale runs from ZERO to FOURTEEN Zero means super duper lots of H+1 ions, a super strong acid. Half way, pH of 7 means equal neither acid or base, but NEUTRAL Over 7 is a base, and pH of 14 is super strong base.

  10. Strong acids weaker acids neutralweaker bases Strong bases 0 1 2 3 4 5 6 7 8 9 10 11 12 13 1 4 pH 0 = LOTS of H+1 ions, almost no OH-1 ions pH 4 = many H+1 ions, some OH-1 ions pH 7 = EQUAL number of both ions, H+1 = OH-1 ions pH 11 = fewer H+1 ions, many OH-1ions pH 14 = LOTS of OH-1ions, almost no H+1 ions

  11. Homework for Tuesday night, due Wednesday, no excuses… Questions: What do all acids have lots of in solutions? What makes bases be bases? What is the name of the scale that we use to measure the strength of acids and bases? What is the name of the man who won the Noble Prize for Chemistry for explaining how about 99% of all acids and bases work? If you put HCl and NaOH solutions together, they will react “sort of like a double replacement reaction, the +ions switch their negative ions. Balance the reaction of putting HCl + NaOH → together Can acids be weak? How is that possible? What does dissociate mean? Table K and L list many acids and bases. Choose another acid and another base, write the name and formula of one you have not seen in this power point presentation. Name four acids and bases that you either eat, or use in your real life at home. There is no question number ten. If you hand in your homework Wednesday you get a free point, otherwise you can only score a 9/10.

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