cgier 34 Flashcards

1
Q

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

A

limestone caverns in featuring statlactics and stalagmites

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2
Q

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

A
  • biological process
  • important for absorption of nutrients
  • important for mineralisation
  • application in drug silvery and diagnostic process
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3
Q

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 —

A
  • staturated
  • undissolved solids
  • ions
  • dissolutions equals the rate of precipitation
  • constant
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4
Q

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 —

A
  • dissolves to from hydrated cations ca2+ and fe- anions
  • increases , increases
    -dissolution
  • precipitation
  • saturated
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5
Q

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

A
  • solubility product constant ( ksp)
  • ksp= dissolved ions only aka the product and no solids
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6
Q

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 —

A
  • greater , greater
  • solids
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7
Q

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

A

one value

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8
Q

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

A
  • infinite
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9
Q

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

A

molar solubility

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10
Q

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

A
  • solubility product constant ( ksp ) and stoichometric coefficient
  • mol/L
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11
Q

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

A

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

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12
Q

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

A
  • ksp
  • larger
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13
Q

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

A
  • different
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14
Q

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

A
  • lowered
  • common ion effect
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15
Q

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

A
  • solubility
  • decreases , increase of 0H , left
  • increases , decrease of OH , right
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16
Q

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)

A

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

17
Q

application of solubility:

A
  • drugs development by having low ksp
  • dental health
18
Q

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

A
  • heavy metal
  • contrast agent for x rays
  • having low solubility
  • won’t get absorbed by the patient
19
Q

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

A
  • acids , decreases the ph
  • low ph
20
Q

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

A

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

21
Q

fluoridation of water

A

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)

22
Q

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

A
  • 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.
23
Q

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

A

-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

24
Q

Doxycycline.HCl – common ion effect

A

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

25
Q

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-

A

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