Exam Pratice Three Flashcards
What is the poH of a sodium with (OH-) ?
120um = 120 x10-6
pOH=-log (120x10-6) =3.9
pH=14-3.9=10.1
What is the pH of the solution of 0.125M?
poH=-log(0H)
poH -log (0.125)=0.90
pH=14-0.9=13.1
Calculate the PH and the H+ concentration of following solution .
pOH = - log (0.02) = 1.7
pH = 14 -1.7 = 12.3 (using pH + pOH = 14)
(b) 12.3 = - log [H+]
antilog (-12.3) = 10-12.3 = [H+] in M
[H+] = 5 × 10-13 M = 500 × 10-15 M = 500 fM
What is the Solution of (H+) 5 mM ?
H+=5mM
ph=-log(5x10-3)=2.3
pOH=14-2.3=11.7-H+
What is the pOH of a solution with (OH-) ?
20mM?
- H+=20mM
pH= -log (20x10-3)=1.69-1.7
PoH=14-1.7=12.3
What is the pH of a solution with H + 20nm ?
20x10-9 M= 20x10-8
pH=-log (H+)
-log (2x10-8)
7.7
What is the pH of a solution with H+ 10nm ?
10x10-9=10x10-8
-log(H+)
-log(1x10”8)
=8
A number which is greater than 10 moves which direction ?
Left
A number less than 10 moves which direction ?
Right
What does 4230?
4.23x10”3
What does 150000 ?
1.5x10”5
What is acid ?
Acid is defined as a substance which gives up a hydrogen proton
What is a base ?
Accepts a proton .
Is a H+ ion a proton ?
Yes because if hydrogen ion looses its electron all that’s left is proton which comprises nucleus
How do hydrogen atoms turn into an ion ?
Due to bonding with two water molecules h20 . The hydrogen atoms leave the electron behind and becomes H+ . (Hydrogen ion) as a single proton which a change o 1 +.
However, the water molecules has lost a proton becoming OH- having a charge of 1 - .It then binds to other molecules becoming hydronium ion (h30) producing a chemical reaction .
2h20 reversible reactions h30 OH-
What happens during the reaction ?2h20 reversible reactions h30 OH-
Water molecule donates h20 one molecule donating a H+ serves an acid . It reverse reaction the OH- accepts the proton and becomes a base .Base means a compound carrying OH-
Does H + exists on its own ?
No because is used to represent t H30 + but does not exists on its own always associates with water molecules in order to form H30 +
Reaction reversed ? What happens the other way ?
2h20 reversible reactions h30 OH-
It reaches a state of equibirum, when they dissociate at the same rate they are being reformed from H+ and OH-.During the equibirum state known as self association of water proceeds in both directions .
What happens to pure water
The pure water is extremely rapid happens in very y small proportion of water molecules .The concenration of water greatly exceeds the concentration of H+ and of OH- are equal in water
What disrupts the balance?
By acids and bases
What does acid donate when its dissolved in water ?
It donates H + to the soliution ,However, an acid increases the hydrogen ions
HC1-H+ + C1- Acidic Solution
What is a substances which reduced hydrogen ions ?
Base how do they do this by reducing H + concentration by accepting hydrogen ions .
What does a single arrow show ?
It can break up easily .These compounds dissociate completely when mixed with water , so hydrocholic aicd called syrong acid and sodium hydroxide called srong base . Na+ + OH+
What are weak acids ?
They are acids which release reversibly .
What is acid base which is conjugate ?
are compounds that differ by the presence of one proton, or H+. All acids have a conjugate base, which is formed when their proton has been donated; likewise, all bases have a conjugate acid, formed after they have accepted a proton.
What is Buffer ?
Its a substance which tries minimise changes in concentration of H+ and OH- in a solution .It does by accepting hydrogen ions from the solution when its decreased .
What do Buffers help with ?
Buffers helps allows biological fluids to maintain a constants pH despite the addition of acids/bases.
Consists of weak acids or its conjugate base /weak base and conjugate acid .
Carbonic acid How is it formed ?
Its formed when Co2 reacts with water in blood plasma. Carbonic acids dissociates to yield a bicarbonate ion .Both these process causes pH to drop following the addition of acid than if acid has been added to pure water .
What happens during this reaction ? H2C02 reversible H30 + Hco3
The excess H+ is neutralised and the pH will drop due t the acid being added .
OH- neutralised and the pH will increase due to less adding of alkali than if acid had been added .pH is minimised changed in pH solution .
What are the three catartogies ?
Neutral : There’s equal amounts of OH-/H - substances
Acids : Greater amounts of H + substances
Base : greater amounts of OH-
What does PKA determine ?
Determined the acids strength
The lower the pKa the stronger the acid .
Stronger acids deprotonate completely this is because of transfer of every acidic proton to solvent etc. .
Weak acids : Partially due to generating some conjugate acids and partially due to weak
HA -H+ +A -
Strong acid conjugate base
Strong acids will readily loose a proton meaning its conjugate base is very stable weak base it doesn’t want a proton
high concentration of H+
HA - H+ + A -
Weak acid , Strong base
The acid does not want to loose the proton it will have a strong conjugate base in which it will easily gain an proton .
