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Acids

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Acid Strength. Strength determined by how easy it is to remove the proton from an acid or add ... Strength Analogy. Another way to think about the strength of ... – PowerPoint PPT presentation

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Title: Acids


1
Acids Bases
  • What is a Buffer?
  • Why is it important?

2
Acids Bases
  • What is an Acid?
  • Chemical species that can donate a proton (H)
  • Ex. HNO3, H2SO4
  • What is a Base?
  • Chemical species that can accept a proton.
  • Ex. NaOH, Ba(OH)2

3
Acid Strength
  • Strength determined by how easy it is to remove
    the proton from an acid or add the proton to a
    base
  • The easier to remove the proton the stronger the
    acid is

4
Conjugate Base
  • An acid can donate a proton
  • When it donates the proton it leaves behind a
    base
  • That base is known as conjugate base
  • HA ? H A-
  • HA is the acid
  • A- is its conjugate base

5
Acid Strength Analogy
  • Another way to think about the strength of an
    acid is to think of a SeeSaw
  • The more tilted the see-saw is the more likely
    the acid (left hand side) is to slide to the
    conjugate base (right side)

6
Equilibrium Weak acids
  • The tilt in the see-saw for a weak acid is not
    big. Therefore it reaches equilibrium after
    some time.
  • HA ? H A-

7
Conjugate Base Properties
  • The Conjugate Base (A-) of a strong acid is a
    WEAK base
  • Similarly the CB of a weak acid is a STRONG base.

8
What is a Buffer?
  • Dictionary Something that serves as a protective
    barrier
  • It can be thought of as a cushion.

9
Buffers and Acids
  • A substance capable neutralizing both acids and
    bases and thereby maintaining the original
    acidity of the solution
  • There are different types of buffers

10
How can we build a buffer?
  • A buffer is made by combining similar amounts of
    a weak acid and its conjugate base
  • Ex. HC2H3O2 ? H C2H3O2-
  • In this case we will add acetic acid to a
    solution and then add sodium acetate salt
  • The buffer capacity depends in the amount of acid
    and base we have in solution

11
Why are Buffers important to ME?
  • Many biological process in the human body rely on
    buffers.
  • One of the most important buffer systems in our
    body is the H2CO3/HCO3- system
  • Most of the food we eat when metabolized produces
    acidic species.
  • This buffer converts takes the acid (H) and
    produces CO2 which is then exhaled.
  • H(aq) HCO3-(aq) ?H2CO3(aq)?H2O(l) CO2(g)
  • The blood is kept pH7.3, if lt 6.8 death may
    occur.

12
Buffers in real life
  • Imagine two lakes.
  • One lake has high amounts of limestone (CaCO3)
  • The other has no limestone present.
  • Acid rain will cause the lake without limestone
    to become acidic, preventing fishes from
    inhabiting it, the other will stay neutral.

CaCO3(s) ? Ca2(aq) CO3-2(aq)
CO32-(aq) H(aq) ? HCO3-(aq)
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