Oceans(O) Flashcards
Define acid and base
Acid=substance which donates H+ in a chemical reaction
Base=substance which accepts H+ in a chemical reaction
What is the equation for the dissociation of an acid?
HA—–>H+ and A-
What is a conjugate base or acid?
A conjugate base means it is able to accept H+ after the reaction has occured
What is pH?
A measurement of hydrogen ions (H+) in a substance
Why is done this way
How is the pH of a strong acid calculated?
-log(H+)
The amount of moles pf H+ ions is equal to the amount of acid (HA) put into solution
Which equation(s) is used to the pH of a weak acid?
Ka=[H+] [A-]/[HA]
What assumptions are used to calculate the pH of a weak acid?
- [H+]=[A-]
- amount/moles of [HA] at eqm is equal to the amount/moles of [HA] put in
How does pH affect pKa
Why is pKa used and what is the equation?
pKA is used when the Ka values is very small
pKa=-log(Ka)
Weaker the acid the higher the pKa value
What equation is used to calculate the pH of a strong base?
[H+]= Kw(1x10(-14)) x [OH-]
-log(H+)
Define buffer
Solutions that can resist changes in pH, despite the addition of small quantities of acid or alkali
How do buffers work?
They remove the majority of any acid or alkali added to the solution
Two types
What are buffers usually made up of?
- A weak acid and one of its salts
- A weak base and one of its salts
What are the two assumptions that the action of buffers is based on?
- All the anions come from the salt
- Almost all the acid molecules put into the buffer remain unchanged
How do you calculate the pH of a base?
[H+]=Ka x acid/salt
Define lattice enthalpy
The enthalpy change when 1 mole of an ionic lattice is formed from its gaseous ions under standard conditions
It is always negative~because bonds are fomed
Define enthalpy of hydration
The enthalpy change for the formation of a solution of ions
Define charge density
A measure of ionic radius and ion’s charge. This depends on two factors:ionic charge and ionic radii
How do you convert solubility in g dm-3 into mol dm-3?
Divide by the molar mass
What is Ksp and give its formula?
Solubility product
This is the sum of the products
What is the difference between strong acids and weak acids?
Strong acids dissociate almost completely in water~nearly all hydrogen ions are released
Weak acids only partially dissociate in water~Eqm is set up which iswell over to the left
What happens to equilibrium when you add more acid or base to an acid-base reaction?
Eqm moves to the right
What equation is used to calculate the pH of a strong base?
Kw=[H+][OH-]
How is pKa calculated?
-log(Ka)
Define a buffer solution
A solution a change in pH when small quantities of acid or base are added
How are acidic buffers made?
A weak acid and one of its salts
Why are buffers important in human cells?
Enzymes work at optimum pH if there is a signifcant change in pH it may lead to bonds within the enzyme breaking. Preventing the enzymes from working
What happens to the position of equilibrium when an acid is added to a buffer?
H+ concentration increases
Majority of H+ combines with an ion from the acid’s salt
Eqm shifts to the left=Reduces H+ concentration
How is the pH of a buffer solution calculated?
Ka=[H+][Salt]/[Acid]
[H+]=Ka x [Salt]/[Acid]
