# Acids, bases and buffers

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• Created by: r98
• Created on: 20-03-16 13:22
What's the definiton of a Bronsted-Lowwry acid?
A substance that can donate a proton (H+ ion).
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What's the definition of a Bronsted-Lowry base?
A substance that can accept a proton (H+ ion).
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What is the only way that acids and bases can react?
In pairs - one acid and one base.
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What are water-soluble bases called? What ions are produced?
Alkalis. They produce OH- ions in aqueous solution.
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What is the name of the H3O+ ion?
The oxonium ion, but can also be called hydronium ion or hydroxonium ion.
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What sub-atomic particles does the H+ ion contain?
Just one proton. NO ELECTRONS!
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What is Kw called?
The ionic product of water.
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What's the formula for Kw?
Kw = Kc x [H2O(l)] or Kw = [H+(aq)]eqm [OH-(aq)]eqm
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What is the value of Kw at 298K?
1.0 x 10-14 mol2 dm-6.
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What does the acidity of a solution depend on? What's it measured on?
It depends on the concentration of H+(aq), and is measured on the pH scale.
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What's the definition of pH?
-log10[H+(aq)].
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To how many decimal places should be pH values be given to?
To 2 dp.
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When is a solution neutral?
When [H+] = [OH-]
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What does Ka stand for and what is its equation?
Ka is the acid dissociation constant and is used for weak acids. Ka ={[H+(aq)] [A-(aq)]}/[HA(aq)]
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What does the value of Ka tell you about the strength of the acid?
The larger the value of Ka, the further the equilibrium is to the right, the more acid is dissociated and the stronger it is.
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How is pKa defined?
pKa = -log10Ka
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In a titration, what is the equivalence point?
The point at which sufficient base has been added to just neutralise the acid (or vice-versa).
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What is an indicator used for?
To find the concentration of a solution of an acid or alkali.
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What is the half-neutralisation point?
The point half-way between the zero and the equivalence point.
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What are buffers?
Solutions that can resist changes of acidity or alkalinity. When small amounts of acid or alkali are added to them, their pH remains almost constant.
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What are buffers designed for?
To keep the concentration of hydrogen ions aand hydroxide ions almost unchanged.
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How do buffers work?
They're based on an equilibrium reaction which will move in the direction to remove either additional hydrogen ions or hydroxide ions if these are added.
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## Other cards in this set

### Card 2

#### Front

What's the definition of a Bronsted-Lowry base?

#### Back

A substance that can accept a proton (H+ ion).

### Card 3

#### Front

What is the only way that acids and bases can react?

### Card 4

#### Front

What are water-soluble bases called? What ions are produced?

### Card 5

#### Front

What is the name of the H3O+ ion?