Protons and their impact Flashcards by Helen Jordan | Brainscape

Q

In low pH, an acid is…

A

…not ionised

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Q

In high pH, an acid is…

A

…completely ionised

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Q

Ka =

A

[H+][A-]/[HA]

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Q

pKa =

A

-log10[Ka]

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Q

Why in low pH is an acid not ionised?

A

Because H+ concentration is high

Equilibrium lies to the left

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Q

Why in high pH does an acid ionise?

A

Because H+ concentration is low

Equilibrium lies to the right

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Q

pKa, pH and ionisation are linked by what?

A

Henderson-Hasselbach equation

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Q

What is the Henderson-Hasselbach equation?

A

% compound ionised = 100/1 + 10 (charge(pH-pKa))

where charge is -1 for acids and 1 for bases

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Q

pH =

A

pKa + log([A-]/[HA])

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Q

What is the deprotonated acid called?

A

The conjugate base of the acid

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Q

Strong acids give…

A

…weak conjugate bases

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Q

What bonds can bases form?

A

Bases can form covalent bonds with H+ ions

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Q

What changes the pKa of protein side chains?

A

The exposure to water

Less water means ionisation is more likely

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Q

How many pKa values does a protein have?

A

Many

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Q

What is the isoelectric point?

A

The pH at which the net charge of the protein is 0

There is an equal number of + and - charged groups

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