Acids and Bases Flashcards

1
Q

What is a bronstead acid?

A

A bronstead acid is a molecule that can donate a proton to a base e.g CH3COO- + H+

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2
Q

What is a bronstead base?

A
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3
Q

What is a base?

A

A molecule that can pick up a proton

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4
Q

What is an acid?

A

Any molecule that contains H joined to a more electronegative atom

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5
Q

What is the pH equation?

A

pH= -log [H3O+]

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6
Q

What is the equation for [H3O+]?

A

[H3O+] = 10-pH

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7
Q

What is the Ka equation?

A

Ka = [A-][H3O+] / [HA]

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8
Q

What does a high pKa mean?

A

A high pKa means that it is a weak acid. A weak acid has a strong conjugate base. A pKa can go into negative digits.

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9
Q

What makes a strong acid?

A
  1. More positive or less negative charge
  2. Charge stabilisation by;
    • Inductive effects
    • Delocalisation
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10
Q

What does the following tell us?

  1. pH < pKa
  2. pH = pKa
  3. pH > pKa
A

When pH is less than pKa there is more acid then base with pH equals pKa they are equal when pH is greater than pKa there is more conjugate base then acid

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11
Q

What is speciation?

A

Speciation is the amount of each species in solution when they are at different forms. This occurs different pH levels depending on the pKa of each acid and conjugate base

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12
Q

What is interesting about amino acids at pH 7?

A

The form a zwitterion which is whern the CHOO- group has lost an H but the NH3+ has an extra charge so the whole molecule has no net charge however both of the side chains are charged

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13
Q

What changes on an amino acid between pH 7 and pH 1?

A

At pH 7 there is a zwitterion where as pH 1 the COO- group has an H = COOH therefore the whole amino acid is +ve charged

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14
Q

What changes on an amino acid between pH 7 and pH 12?

A

At pH 7 a zwitterion forms however at pH 12 the NH3 group has lost an H and is no longer +ve this means that the whole molecule is now has a -ve charge

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15
Q

What is one assumption we make when a strong acid reacts with water?

A

Only the strong acids contributes to the H30+ concentration this is not true when the calculated pH is > 6

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16
Q

What is one assumption we make when a strong base reacts with water?

A

We make the assumption that only strong bases contribute to the OH- concentration this is not true when the pH < 8.

It is important to remember that pH = 14 - pOH

17
Q

What is an amphoteric species? what is the equation?

A

An amphoteric species can be both a weak acid and a weak base.

pH =0.5 (pKa1 = pKa2)

18
Q

What is a buffer?

A

The buffer is when a weak acid and its congee get bass exist in water this resists changes to pH when other acids or bases added.

19
Q

What is the difference between a pH buffered solution and an unbuffered solution

A

A buffered solution will not be affected by dilution however an Unbuffered solution Will be affected by dilution

20
Q

What is important about the Half- equivalence point?

A

It is where pH = pKa

21
Q

what is the equivalence point?

A

Where the reaction is 100% complete and there is only conjugate acid present

22
Q

What are indicators?

A

Acids and bases