Acids and bases Flashcards
Define acidosis
A process causing increased acidity in the blood and other body tissues. If not further qualified, it usually refers to acidity of the blood plasma.
What is the blood pH below when acidosis occurs?
7.35
Define alkalosis
The result of a process reducing hydrogen ion concentration of arterial blood plasma
What is the blood pH above when alkalosis occurs?
7.45
What is the range of normal physiological pH?
7-7.5
Where is it likely that the pH is outside the normal range?
Stomach- due to the stomach acids
Pancreas- due to pancreatic juice
Write the equation for the dissociation of water.
H2O ⇌ H+ + OH-
What’s the concentration of hydrogen ions in pure water at 25°C?
10^(-7) M
How is pH calculated?
-log10([H+])
Write the equation for Kw.
Kw=[H+][OH-]
Give the value of Kw
10^-14 M^2
This is because [H+] and [OH-] in pure water are both 10^-7
Define the term ‘acid’
A proton donor.
Define the term ‘base’
A proton acceptor
Define the term ‘conjugate base’
The chemical formed when an acid ionises
Define the term ‘conjugate acid’
The acid formed when a base binds to a proton
Write the ionisation equilibrium for a weak acid
HA ⇌ H+ + A-
What is the formula for the equilibrium constant, Ka?
Ka= [H+][A-]/[HA]
What does the size of Ka indicate about the strength of an acid?
The larger the Ka value, the stronger the acid
How is pKa worked out?
pKa= -log10(Ka)
What is the Henderson-Hasselbalch equation?
pH= pKa + log([A-]/[HA])
When does pH=pKa?
When [HA]=[A-] because it means that the log([A-]/[HA]) =0
When is pH smaller than pKa?
When there is more HA in solution
When is pH larger than pKa?
When there is more A- in solution
Define the term ‘buffer’
A substance that resists a change in pH when a small amount of acid or base is added
