cgier 34

Question 1

the dissolution and precipitation of limestone ( CaC03) is responsible for the formation of

Answer 1

limestone caverns in featuring statlactics and stalagmites

Question 2

the solubility phenomena is important as: nail –> na + cl because its important for — like:

Answer 2

• biological process
• important for absorption of nutrients
• important for mineralisation
• application in drug silvery and diagnostic process

Question 3

solubility equilibria is in — solutions where dynamic equilibrium exists between — and — and the rate of the —- is — to the rate of —- and the concentration of ions will be —

Answer 3

• staturated
• undissolved solids
• ions
• dissolutions equals the rate of precipitation
• constant

Question 4

solids dissolving to form aqouse solutions as:
- ionic solid ( CaF2) — to form completely separate — and —
- as dissolution proceeds the ca2+ and f- will —-
- which will lead to – probability of ions colliding to —
- second competing process is going the opposite directions
- going right is: — and going left is —
- at equilibrium the solution is said to be —

Answer 4

• dissolves to from hydrated cations ca2+ and fe- anions
• increases , increases
  -dissolution
• precipitation
• saturated

Question 5

— is the constant for the equilibrium between solid solutes and ions in saturated solutions

Answer 5

• solubility product constant ( ksp)
• ksp= dissolved ions only aka the product and no solids

Question 6

why there’s no solids in ksp?
more solid leads to – in surface area which — the solubility which gives greater chance for ions to reform into —

Answer 6

• greater , greater
• solids

Question 7

solubility product has only — value for a given solid at a particular temp

Answer 7

one value

Question 8

solubility product has – number of values at a given temp depending on their condition( as ph, common ion ) that impacts the solubityy

Answer 8

• infinite

Question 9

– is the number of moles of substance that can be dissolved in 1 litter for solution reaching saturation

Answer 9

molar solubility

Question 10

the molar solubility can be calculated from — and — and the units are —-

Answer 10

• solubility product constant ( ksp ) and stoichometric coefficient
• mol/L

Question 11

example: calculate the ksp for CaF2 if the molar solubility of CaF2 is 3.4 x 10-4 mol/l
formula: caf2 –> ca2+ + 2f-

Answer 11

ksp = dissolved ions
= [3.4 x 10-4 ] x [2 x 3.4 x 10-4]power 2
= [ 4 x 3.4 x 10-4 ] power 3

Question 12

— are direct indicators for solubility for different salts if the salts produce the same number of ions
larger the KSP – the solubity

Answer 12

• ksp
• larger

Question 13

ksp can’t be used as a direct comparison of solubility for salts that produce — number of ions in a solution

Answer 13

• different

Question 14

solubility is – when in the presence of a second sole which is known as —- effect

Answer 14

• lowered
• common ion effect

Question 15

ph affects the —
as we increase the ph —–
as we decrease the ph

Answer 15

• solubility
• decreases , increase of 0H , left
• increases , decrease of OH , right

Question 16

the impact of ph in the following equation:
Ag3PO4 (s) —> <— 3Ag+ (aq) + PO43- (aq)
( PO4 3- is a weak base which will create H+ to from HPO4 -2)

Answer 16

increase of the ph decreases the solubility and decrease in PO3
here the solubility will increase bc of the po4that’ll drive the equilibrium to the right

Question 17

application of solubility:

Answer 17

• drugs development by having low ksp
• dental health

Question 18

barium sulphate is a – metal and is used for — adminstered as suspension. Its toxic but by —- it won’t get —

Answer 18

• heavy metal
• contrast agent for x rays
• having low solubility
• won’t get absorbed by the patient

Question 19

tooth decay occurs due to bacteria producing — that – the ph.
the main component of the teeth is hydrocypetate and is more soluble at —

Answer 19

• acids , decreases the ph
• low ph

Question 20

formula of tooth decay is — and the reverse is called —- cavities can develop when its slower than — of hydroxyapatite

Answer 20

-Ca5OH(PO4)3 (s) –> <– 5Ca2+ (aq) + 3(PO43-) (aq) + OH- (aq)
- reminerlasion
- slower than dissolution

Question 21

fluoridation of water

Answer 21

For decades many countries have been adding CaF2 to drinking water.
CaF2 increases the concentration of F- in the saliva.
During remineralisation fluorapatite, Ca5F(PO4)3, can be formed in the enamel of teeth and at a faster rate than hydroxyapatite reforms.
Fluorapatite is less soluble at acidic pH values compared to hydroxyapatite and therefore reduces probability of developing tooth decay.
Ca5F(PO4)3 (s)–> <– 5Ca2+ (aq) + 3(PO43-) (aq) + F- (aq)

Question 22

solubility of drugs can be significantly modified by forming — the solubility will — but certain counter ions — the solubility

Answer 22

• salts ( which impacts the choice of salts )
• increase , decrease
• information:
  Erythromycin is unstable at low pH. Erythromycin stearate is less soluble and therefore less susceptible to degradation. The salt dissociates in the intestine and can be absorbed.

Question 23

Formulations developed for oral administration need to take into account the high concentrations —

Answer 23

-cl- ions in the stomach
-Poorly soluble salts containing a Cl- counter ion may precipitate and therefore become less available for absorption due to the common ion effect of the Cl- ions

Question 24

Doxycycline.HCl – common ion effect

Answer 24

4 times more soluble in pure water compared to 0.1 M HCl
More soluble in 0.1 M methylsulphonic acid compared to HCl
Specificity for Cl- ions, i.e. common ion effect

Question 25

calculate:
Lead(II) iodide, PbI2, has a Ksp of 7.1 x 10-9 at 25 o C. Calculate the molar solubility of PbI2 in water at 25 o.
PbI2 –> ,<– Pb2+ + 2I-

Answer 25

Ksp = [Pb2+] [I-]2 = (s)(2s)2 = 7.1 x 10-9
4s3 = 7.1 x 10-9
s3 = 1.8 x 10-9
s = (1.8 x 10-9)1/3 = 1.2 x 10-3