Home >
Community >
Why does potassium hydroxide seem to be better at being a base compared to sodium hydroxide when both are strong bases? (I might be wrong saying that it seems better)
Upvote
16
Downvote
+ Hydroxides
+ Sodium hydroxide
+ Sodium
+ Chemistry
Posted by
Adrian Poaca
Why does potassium hydroxide seem to be better at being a base compared to sodium hydroxide when both are strong bases? (I might be wrong saying that it seems better)
K+ of KOH is bigger than Na+ of NaOH, BIGGER CATION POLARIZES LESS AND MORE IONIC!!
So, KOH is more IONIC and dissolves better releasing more OH- . Hence, it is a better base!
Both are strong bases in aqeous solution but (NOT IN ORGANIC MEDIA) the betterness of KOH is evident, in the following reactions:-
1.Liquid soap/ more soluble soaps/ soft soaps are made with KOH and not with NaOH.. meaning that KOH is better at being a base!
2.More Noble METAL Pt is READILY attacked by fused KOH. NaOH reacts very slowly!
3. Some elimination reactions are worked out by KOH/ alcoholic solutions not by NaOH!
Burn a large quantity of wood. Add water to the ashes and filter out the insoluble material. Evaporate the solution down until crystals start to appear: these are potassium carbonate (potash). When cold, ass enough water to the solution to re-dissolve the crystals.
Burn some limestone (calcium carbonate) in a very hot fire contained within a furnace with plenty of ventilation at the bottom. This will make calcium oxide (quicklime). Allow to cool and add water very slowly. The lime will absorb it, swell and break up. You now have calcium hydroxide (slaked lime).
Add the slaked lime slurry to the solution of potash. Filter. Your clear solution contains potassium hydroxide; the insoluble matter is calcium carbonate.
Burn a large quantity of wood. Add water to the ashes and filter out the insoluble material. Evaporate the solution down until crystals start to appear: these are potassium carbonate (potash). When cold, ass enough water to the solution to re-dissolve the crystals.
Burn some limestone (calcium carbonate) in a very hot fire contained within a furnace with plenty of ventilation at the bottom. This will make calcium oxide (quicklime). Allow to cool and add water very slowly. The lime will absorb it, swell and break up. You now have calcium hydroxide (slaked lime).
Add the slaked lime slurry to the solution of potash. Filter. Your clear solution contains potassium hydroxide; the insoluble matter is calcium carbonate.
Potassium hydroxide I.e. KOH is more basic than sodium hydroxide I.e. NaOH. Since the size of alkali metals increases down the group I.e. K has larger size than Na, so the bond strength of KOH is less than NaOH. Hence, it is easier for KOH to remove its OH- group. Hence KOH is more basic than NaOH.
Potassium hydroxide I.e. KOH is more basic than sodium hydroxide I.e. NaOH. Since the size of alkali metals increases down the group I.e. K has larger size than Na, so the bond strength of KOH is less than NaOH. Hence, it is easier for KOH to remove its OH- group. Hence KOH is more basic than NaOH.
In water, both potassium hydroxide and sodium hydroxide are strong bases which completely dissociates to give OH⁻ ion. Therefore, their equi-molar aqueous solutions have the same basic strength.
However, potassium hydroxide is stronger base than sodium hydroxide in non-aqueous solutions, in which potassium hydroxide and sodium hydroxide do not completely dissociate. This is because the inter-ionic distance of potassium hydroxide is greater than that of sodium hydroxide due to the ionic radius of potassium ion is greater than that of sodium ion. This leads to the fact that potassium hydroxide dissociates more readily than sodium hydroxide as the electrostatic attractive force between a pair of opposite ions is inversely proportional to the square of the inter-ionic distance.
In water, both potassium hydroxide and sodium hydroxide are strong bases which completely dissociates to give OH⁻ ion. Therefore, their equi-molar aqueous solutions have the same basic strength.
However, potassium hydroxide is stronger base than sodium hydroxide in non-aqueous solutions, in which potassium hydroxide and sodium hydroxide do not completely dissociate. This is because the inter-ionic distance of potassium hydroxide is greater than that of sodium hydroxide due to the ionic radius of potassium ion is greater than that of sodium ion. This leads to the fact that potassium hydroxide dissociates more readily than sodium hydroxide as the electrostatic attractive force between a pair of opposite ions is inversely proportional to the square of the inter-ionic distance.
It is better in several ways that usually do not matter. It is more soluble than NaOH at higher concentrations (1.2 kg/L versus 1 kg/L). It is also used in some manufacturing situations. Why is not clear. Read the Wikipedia page for these situations.
The one and most important property that makes NaOH better, it is much cheaper than KOH.
It is better in several ways that usually do not matter. It is more soluble than NaOH at higher concentrations (1.2 kg/L versus 1 kg/L). It is also used in some manufacturing situations. Why is not clear. Read the Wikipedia page for these situations.
The one and most important property that makes NaOH better, it is much cheaper than KOH.
All metal hydroxides other than those of the alkali Li, Na, K, Rb, Cs, and of the heavier alkaline earth metals Ca, Sr and Ba, are insoluble, and therefore, do not release OH(-) ions to water solutions, therefore not altering the pH. Remember hydroxides such as Mg(OH)2 an alkaline earth metal hydroxide, or Al(OHO)3 only dissolve in acidic media and can be used as antacids for the relief of stomach aches.
It is interesting that you pay attention to two chemical equations:
2H2O = OH(-) + H3O(+)
water self equilibrium, the amount of OH (-) ions are counterbalanced by H3O(+), and the result is a neutral solution, ph around 7.
MOH(s) → M(+)(aq) + OH(-)(aq)
as the dissolution of an alkali metal hydroxide M. Note that the amount of OH(-) release will upset the original balance OH(-) + H3O(+), increasing the OH(-) content, making the solution alkaline, therefore very corrosive, and with values oh pH well above 7. But this property is exclusive of the hydroxides of the Group 1 metals, and of those heavy Group 2 metals, as said before. It is a nice example of how things that dissolve in water can alter drastically its chemical properties. On the other hand, dissolving things like table salt, or sugar in water will not alter the water chemistry, and the solution will either taste sweet or salty and will have other different physical properties, but the equilibrium 2H2O = OH(-) + H3O(+) will be maintained.
(In the last case you could write
NaCl → Na(+)(aq) + Cl(-)(aq)
to show that dissolution of table salt does not disrupt the original self equilibrium of water)
All metal hydroxides other than those of the alkali Li, Na, K, Rb, Cs, and of the heavier alkaline earth metals Ca, Sr and Ba, are insoluble, and therefore, do not release OH(-) ions to water solutions, therefore not altering the pH. Remember hydroxides such as Mg(OH)2 an alkaline earth metal hydroxide, or Al(OHO)3 only dissolve in acidic media and can be used as antacids for the relief of stomach aches.
It is interesting that you pay attention to two chemical equations:
2H2O = OH(-) + H3O(+)
water self equilibrium, the amount of OH (-) ions are counterbalanced by H3O(+), and the result is a neutral solution, ph around 7.
MOH(s) → M(+)(aq) + OH(-)(aq)
as the dissolution of an alkali metal hydroxide M. Note that the amount of OH(-) release will upset the original balance OH(-) + H3O(+), increasing the OH(-) content, making the solution alkaline, therefore very corrosive, and with values oh pH well above 7. But this property is exclusive of the hydroxides of the Group 1 metals, and of those heavy Group 2 metals, as said before. It is a nice example of how things that dissolve in water can alter drastically its chemical properties. On the other hand, dissolving things like table salt, or sugar in water will not alter the water chemistry, and the solution will either taste sweet or salty and will have other different physical properties, but the equilibrium 2H2O = OH(-) + H3O(+) will be maintained.
(In the last case you could write
NaCl → Na(+)(aq) + Cl(-)(aq)
to show that dissolution of table salt does not disrupt the original self equilibrium of water)
Both sodium hydroxide and its potassium cousin are strong bases meaning they are fully ionized in an aqueous solution to the metal cation and hydroxide ion. Therefor, since pH (a measure of acidity or basicity) is commonly thought of as the negative log of the hydrogen ion concentration, the pH should be the same for equimolar solutions of either compound.
And at low concentrations, that’s pretty much true.
But the measured value of pH is actually the negative log of not the hydrogen ion concentration, but rather of the hydrogen ion activity which is the product of the activity coefficient and the concentration. In dilute environments, these are the same, but not at high concentrations, where they diverge. In those regions of divergence, the mean activity coefficients for aqueous potassium hydroxide are greater than for aqueous sodium hydroxide of equimolar concentration.
Hence, the potassium hydroxide solution will measure as more basic.
But why do the two different compounds have different activity coefficients, I hear you asking. It almost certainly has to do with the difference in hydration (that is, the water molecules surrounding the two cations). After all, potassium ion is bigger than sodium ion and its positive nucleus shielded by more negative elections, to name but two differences. But beyond that, things get murky. A number of papers have appeared over the years with various detailed but differing explanations. A critical review is beyond a Quora answer.
Both sodium hydroxide and its potassium cousin are strong bases meaning they are fully ionized in an aqueous solution to the metal cation and hydroxide ion. Therefor, since pH (a measure of acidity or basicity) is commonly thought of as the negative log of the hydrogen ion concentration, the pH should be the same for equimolar solutions of either compound.
And at low concentrations, that’s pretty much true.
But the measured value of pH is actually the negative log of not the hydrogen ion concentration, but rather of the hydrogen ion activity which is the product of the activity coefficient and the concentration. In dilute environments, these are the same, but not at high concentrations, where they diverge. In those regions of divergence, the mean activity coefficients for aqueous potassium hydroxide are greater than for aqueous sodium hydroxide of equimolar concentration.
Hence, the potassium hydroxide solution will measure as more basic.
But why do the two different compounds have different activity coefficients, I hear you asking. It almost certainly has to do with the difference in hydration (that is, the water molecules surrounding the two cations). After all, potassium ion is bigger than sodium ion and its positive nucleus shielded by more negative elections, to name but two differences. But beyond that, things get murky. A number of papers have appeared over the years with various detailed but differing explanations. A critical review is beyond a Quora answer.
K+ of KOH is bigger than Na+ of NaOH, BIGGER CATION POLARIZES LESS AND MORE IONIC!!
So, KOH is more IONIC and dissolves better releasing more OH- . Hence, it is a better base!
Both are strong bases in aqeous solution but (NOT IN ORGANIC MEDIA) the betterness of KOH is evident, in the following reactions:-
1.Liquid soap/ more soluble soaps/ soft soaps are made with KOH and not with NaOH.. meaning that KOH is better at being a base!
2.More Noble METAL Pt is READILY attacked by fused KOH. NaOH reacts very slowly!
3. Some elimination reactions are worked out by KOH/ alcoholic solutions not by NaOH!
K+ of KOH is bigger than Na+ of NaOH, BIGGER CATION POLARIZES LESS AND MORE IONIC!!
So, KOH is more IONIC and dissolves better releasing more OH- . Hence, it is a better base!
Both are strong bases in aqeous solution but (NOT IN ORGANIC MEDIA) the betterness of KOH is evident, in the following reactions:-
1.Liquid soap/ more soluble soaps/ soft soaps are made with KOH and not with NaOH.. meaning that KOH is better at being a base!
2.More Noble METAL Pt is READILY attacked by fused KOH. NaOH reacts very slowly!
3. Some elimination reactions are worked out by KOH/ alcoholic solutions not by NaOH!
More
VOTE
Burn a large quantity of wood. Add water to the ashes and filter out the insoluble material. Evaporate the solution down until crystals start to appear: these are potassium carbonate (potash). When cold, ass enough water to the solution to re-dissolve the crystals.
Burn some limestone (calcium carbonate) in a very hot fire contained within a furnace with plenty of ventilation at the bottom. This will make calcium oxide (quicklime). Allow to cool and add water very slowly. The lime will absorb it, swell and break up. You now have calcium hydroxide (slaked lime).
Add the slaked lime slurry to the solution of potash. Filter. Your clear solution contains potassium hydroxide; the insoluble matter is calcium carbonate.
Burn a large quantity of wood. Add water to the ashes and filter out the insoluble material. Evaporate the solution down until crystals start to appear: these are potassium carbonate (potash). When cold, ass enough water to the solution to re-dissolve the crystals.
Burn some limestone (calcium carbonate) in a very hot fire contained within a furnace with plenty of ventilation at the bottom. This will make calcium oxide (quicklime). Allow to cool and add water very slowly. The lime will absorb it, swell and break up. You now have calcium hydroxide (slaked lime).
Add the slaked lime slurry to the solution of potash. Filter. Your clear solution contains potassium hydroxide; the insoluble matter is calcium carbonate.
More
VOTE
It is combination of Potassium (K) and Hydroxl group OH.
It becomes KOH which is a base due to presence of OH group.
Plz upvote if you find it good information though small.
It is combination of Potassium (K) and Hydroxl group OH.
It becomes KOH which is a base due to presence of OH group.
Plz upvote if you find it good information though small.
More
VOTE
Maybe you are better at answering your own question. In what way does it seem to be better? Is it in fact a stronger base? Does it ionise better?
Maybe you are better at answering your own question. In what way does it seem to be better? Is it in fact a stronger base? Does it ionise better?
More
VOTE
The decreasing order of the basic strength of the hydroxides of alkali metals is :
CsOH > RbOH > KOH >NaOH > LiOH.
Therefore, KOH is a stronger base and hence, a better base than NaOH.
The decreasing order of the basic strength of the hydroxides of alkali metals is :
CsOH > RbOH > KOH >NaOH > LiOH.
Therefore, KOH is a stronger base and hence, a better base than NaOH.
More
VOTE
Potassium hydroxide I.e. KOH is more basic than sodium hydroxide I.e. NaOH. Since the size of alkali metals increases down the group I.e. K has larger size than Na, so the bond strength of KOH is less than NaOH. Hence, it is easier for KOH to remove its OH- group. Hence KOH is more basic than NaOH.
Potassium hydroxide I.e. KOH is more basic than sodium hydroxide I.e. NaOH. Since the size of alkali metals increases down the group I.e. K has larger size than Na, so the bond strength of KOH is less than NaOH. Hence, it is easier for KOH to remove its OH- group. Hence KOH is more basic than NaOH.
More
VOTE
In water, both potassium hydroxide and sodium hydroxide are strong bases which completely dissociates to give OH⁻ ion. Therefore, their equi-molar aqueous solutions have the same basic strength.
However, potassium hydroxide is stronger base than sodium hydroxide in non-aqueous solutions, in which potassium hydroxide and sodium hydroxide do not completely dissociate. This is because the inter-ionic distance of potassium hydroxide is greater than that of sodium hydroxide due to the ionic radius of potassium ion is greater than that of sodium ion. This leads to the fact that potassium hydroxide dissociates more readily than sodium hydroxide as the electrostatic attractive force between a pair of opposite ions is inversely proportional to the square of the inter-ionic distance.
In water, both potassium hydroxide and sodium hydroxide are strong bases which completely dissociates to give OH⁻ ion. Therefore, their equi-molar aqueous solutions have the same basic strength.
However, potassium hydroxide is stronger base than sodium hydroxide in non-aqueous solutions, in which potassium hydroxide and sodium hydroxide do not completely dissociate. This is because the inter-ionic distance of potassium hydroxide is greater than that of sodium hydroxide due to the ionic radius of potassium ion is greater than that of sodium ion. This leads to the fact that potassium hydroxide dissociates more readily than sodium hydroxide as the electrostatic attractive force between a pair of opposite ions is inversely proportional to the square of the inter-ionic distance.
More
VOTE
It is better in several ways that usually do not matter. It is more soluble than NaOH at higher concentrations (1.2 kg/L versus 1 kg/L). It is also used in some manufacturing situations. Why is not clear. Read the Wikipedia page for these situations.
The one and most important property that makes NaOH better, it is much cheaper than KOH.
It is better in several ways that usually do not matter. It is more soluble than NaOH at higher concentrations (1.2 kg/L versus 1 kg/L). It is also used in some manufacturing situations. Why is not clear. Read the Wikipedia page for these situations.
The one and most important property that makes NaOH better, it is much cheaper than KOH.
More
VOTE
All metal hydroxides other than those of the alkali Li, Na, K, Rb, Cs, and of the heavier alkaline earth metals Ca, Sr and Ba, are insoluble, and therefore, do not release OH(-) ions to water solutions, therefore not altering the pH. Remember hydroxides such as Mg(OH)2 an alkaline earth metal hydroxide, or Al(OHO)3 only dissolve in acidic media and can be used as antacids for the relief of stomach aches.
It is interesting that you pay attention to two chemical equations:
2H2O = OH(-) + H3O(+)
water self equilibrium, the amount of OH (-) ions are counterbalanced by H3O(+), and the result is a neutral solution, ph around 7.
MOH(s) → M(+)(aq) + OH(-)(aq)
as the dissolution of an alkali metal hydroxide M. Note that the amount of OH(-) release will upset the original balance OH(-) + H3O(+), increasing the OH(-) content, making the solution alkaline, therefore very corrosive, and with values oh pH well above 7. But this property is exclusive of the hydroxides of the Group 1 metals, and of those heavy Group 2 metals, as said before. It is a nice example of how things that dissolve in water can alter drastically its chemical properties. On the other hand, dissolving things like table salt, or sugar in water will not alter the water chemistry, and the solution will either taste sweet or salty and will have other different physical properties, but the equilibrium 2H2O = OH(-) + H3O(+) will be maintained.
(In the last case you could write
NaCl → Na(+)(aq) + Cl(-)(aq)
to show that dissolution of table salt does not disrupt the original self equilibrium of water)
All metal hydroxides other than those of the alkali Li, Na, K, Rb, Cs, and of the heavier alkaline earth metals Ca, Sr and Ba, are insoluble, and therefore, do not release OH(-) ions to water solutions, therefore not altering the pH. Remember hydroxides such as Mg(OH)2 an alkaline earth metal hydroxide, or Al(OHO)3 only dissolve in acidic media and can be used as antacids for the relief of stomach aches.
It is interesting that you pay attention to two chemical equations:
2H2O = OH(-) + H3O(+)
water self equilibrium, the amount of OH (-) ions are counterbalanced by H3O(+), and the result is a neutral solution, ph around 7.
MOH(s) → M(+)(aq) + OH(-)(aq)
as the dissolution of an alkali metal hydroxide M. Note that the amount of OH(-) release will upset the original balance OH(-) + H3O(+), increasing the OH(-) content, making the solution alkaline, therefore very corrosive, and with values oh pH well above 7. But this property is exclusive of the hydroxides of the Group 1 metals, and of those heavy Group 2 metals, as said before. It is a nice example of how things that dissolve in water can alter drastically its chemical properties. On the other hand, dissolving things like table salt, or sugar in water will not alter the water chemistry, and the solution will either taste sweet or salty and will have other different physical properties, but the equilibrium 2H2O = OH(-) + H3O(+) will be maintained.
(In the last case you could write
NaCl → Na(+)(aq) + Cl(-)(aq)
to show that dissolution of table salt does not disrupt the original self equilibrium of water)
More
VOTE
The answer to this question is not obvious.
Both sodium hydroxide and its potassium cousin are strong bases meaning they are fully ionized in an aqueous solution to the metal cation and hydroxide ion. Therefor, since pH (a measure of acidity or basicity) is commonly thought of as the negative log of the hydrogen ion concentration, the pH should be the same for equimolar solutions of either compound.
And at low concentrations, that’s pretty much true.
But the measured value of pH is actually the negative log of not the hydrogen ion concentration, but rather of the hydrogen ion activity which is the product of the activity coefficient and the concentration. In dilute environments, these are the same, but not at high concentrations, where they diverge. In those regions of divergence, the mean activity coefficients for aqueous potassium hydroxide are greater than for aqueous sodium hydroxide of equimolar concentration.
Hence, the potassium hydroxide solution will measure as more basic.
But why do the two different compounds have different activity coefficients, I hear you asking. It almost certainly has to do with the difference in hydration (that is, the water molecules surrounding the two cations). After all, potassium ion is bigger than sodium ion and its positive nucleus shielded by more negative elections, to name but two differences. But beyond that, things get murky. A number of papers have appeared over the years with various detailed but differing explanations. A critical review is beyond a Quora answer.
The answer to this question is not obvious.
Both sodium hydroxide and its potassium cousin are strong bases meaning they are fully ionized in an aqueous solution to the metal cation and hydroxide ion. Therefor, since pH (a measure of acidity or basicity) is commonly thought of as the negative log of the hydrogen ion concentration, the pH should be the same for equimolar solutions of either compound.
And at low concentrations, that’s pretty much true.
But the measured value of pH is actually the negative log of not the hydrogen ion concentration, but rather of the hydrogen ion activity which is the product of the activity coefficient and the concentration. In dilute environments, these are the same, but not at high concentrations, where they diverge. In those regions of divergence, the mean activity coefficients for aqueous potassium hydroxide are greater than for aqueous sodium hydroxide of equimolar concentration.
Hence, the potassium hydroxide solution will measure as more basic.
But why do the two different compounds have different activity coefficients, I hear you asking. It almost certainly has to do with the difference in hydration (that is, the water molecules surrounding the two cations). After all, potassium ion is bigger than sodium ion and its positive nucleus shielded by more negative elections, to name but two differences. But beyond that, things get murky. A number of papers have appeared over the years with various detailed but differing explanations. A critical review is beyond a Quora answer.
More
VOTE