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What is the pH of refined white sugar?

C

Cawchy87

Diamond Member
If you put sugar in lemon juice it makes it sweet and pleasent to the taste. But is this a chemical reaction? Is sugar a base? What is going on at the molecular level when this reaction occurs?
 
*thinks back reallllllly hard*

If I remember clearly, sugar is a non-polar compound which does not dissolve into ions when put into water. Thus, sugar is neither a base or an acid. Beyond that, I have no clue if there's a chemical reaction happening. I would guess that sugar is playing some trick on your taste buds.
 
SUgar doesn't counteract the acid, it just softens the taste.

Take soft drinks for example, tonnes of sugar in them, but they're still highly acidic (or so my dentist says).
 
Even if it did decrease the acidity, that wouldn't necessarily mean it's a base... it could also be acting as a buffer in the solution.
 
Originally posted by: DrPizza
Even if it did decrease the acidity, that wouldn't necessarily mean it's a base... it could also be acting as a buffer in the solution.
Click to expand...

I wish you were my teacher, you seem to have an answer to all my questions! Also, could you expand on the idea of a buffer? (I going into gr. 12)
 
A buffer is a substance (or mixture of substances) that resist a change in pH.

For example, pure water has H+ and OH- ions in balance and has a pH of 7. Let's say that you have a beaker of pure water and add a few drops of dilute hydrochoric acid to make a solution with a pH of 5.

This solution will be very susceptible to pH changes - a few more drops of acid and the pH will drop down to 4. A few drops of strong alkali solution and it will be back at 7.

A buffered solution changes pH much more slowly as acid or alkali is added. E.g. Adding the same amount of acid as in the experiment above, the pH may only move from 5 to 4.9
 
Originally posted by: Cawchy87
Originally posted by: DrPizza
Even if it did decrease the acidity, that wouldn't necessarily mean it's a base... it could also be acting as a buffer in the solution.
Click to expand...

I wish you were my teacher, you seem to have an answer to all my questions! Also, could you expand on the idea of a buffer? (I going into gr. 12)
Click to expand...

What about my answer? Sugar is non-polar and will not dissolve into ions in polar liquids. That is why sugar is not a base or an acid.
 
What about my answer? Sugar is non-polar and will not dissolve into ions in polar liquids. That is why sugar is not a base or an acid.[/quote]


No no... pH is the concentration of dissolved H+ ions taken as a negative logarithm. ie. Pure water has a balanced concentration of H+ and OH- ions of 10^-7 each. The pH will be -log(10^-7) making it 7. Sugar is definitely polar because it is a 6-ring organic compound containing C, H and O. O (oxygen) is highly electronegative and causes polarity in the compound.

It is not the fact that sugar will not dissolve into ions, it is just the fact that sugar tends not to release H or OH groups when it is dissolved in water; which takes away acid or base properties.

If you really want to get specific, any ion will can be considered an acid or base, but if they make no significant contribution to the pH, they won't be considered an acid, which eliminates compounds that don't donate H+ or OH- ions to solution.
 
Originally posted by: thelordemperor
SUgar doesn't counteract the acid, it just softens the taste.

Take soft drinks for example, tonnes of sugar in them, but they're still highly acidic (or so my dentist says).
Click to expand...

Yes Cola is very acidic and is strong enough to be used to clean and degrease engines if you really wanted to.
 
Originally posted by: mickles

No no... pH is the concentration of dissolved H+ ions taken as a negative logarithm. ie. Pure water has a balanced concentration of H+ and OH- ions of 10^-7 each. The pH will be -log(10^-7) making it 7. Sugar is definitely polar because it is a 6-ring organic compound containing C, H and O. O (oxygen) is highly electronegative and causes polarity in the compound.

It is not the fact that sugar will not dissolve into ions, it is just the fact that sugar tends not to release H or OH groups when it is dissolved in water; which takes away acid or base properties.

If you really want to get specific, any ion will can be considered an acid or base, but if they make no significant contribution to the pH, they won't be considered an acid, which eliminates compounds that don't donate H+ or OH- ions to solution.
Click to expand...

Oooh... true true, the lack of symmetry creates a slight polarity in sugar. I forgot about that. Regardless, determining the acidity/basic properties of a substance based on the contribution of H or OH ions is only half the story. What I was trying to allude to was in regards to salts. Some salts when dissolved do not 'contribute' OH or H ions, but result in an acidic/basic pH level. Sorry if I wasn't clear.
 
Originally posted by: TuxDave



Oooh... true true, the lack of symmetry creates a slight polarity in sugar. I forgot about that. Regardless, determining the acidity/basic properties of a substance based on the contribution of H or OH ions is only half the story. What I was trying to allude to was in regards to salts. Some salts when dissolved do not 'contribute' OH or H ions, but result in an acidic/basic pH level. Sorry if I wasn't clear.
Click to expand...


Yeah. That's what I was trying to get to with respect to the properties of ions that will affect pH, but they are negligible. Cl- ions are considered weak bases, but the effect they have is next to zero.
 
Originally posted by: mickles
However, I'm 99% sure there are compounds that exhibit behaviors as you describe.
Click to expand...

Yeah, you baking soda is probably the most typical example if I recall correctly.
 
Yes, baking soda is sodium bicarbonate. It falls in the buffer area and considered a weak base.

Carbonic acid, H2CO3 will dissolve in solution to make H+ and HCO3-. Since H+ is a strong acid, HCO3- must be a weak conjugate base; unless my memory fails me completely 🙂
 
Originally posted by: mickles
Originally posted by: thelordemperor
SUgar doesn't counteract the acid, it just softens the taste.

Take soft drinks for example, tonnes of sugar in them, but they're still highly acidic (or so my dentist says).
Click to expand...

Yes Cola is very acidic and is strong enough to be used to clean and degrease engines if you really wanted to.
Click to expand...

In fact cola is a great degreaser. It is also a great way of cleaning stickers off glass and plastics. Just as effective and cheaper than industrial alternatives
 
If sugar was a base, wouldn't it produce carbon dioxide when added to an acidic solution, as does baking soda when added to vinegar?
 
Adding a base to acid will give you water and some sort of salt.

(H+ A-) + (B+ OH-) --> H2O + AB

AB is your resultant salt.

It gets a little complicated with buffer solutions... And I don't care much to recall, I just remember it involves a free ion salt presence in the first place.
 
Originally posted by: mickles
Yes, baking soda is sodium bicarbonate. It falls in the buffer area and considered a weak base.

Carbonic acid, H2CO3 will dissolve in solution to make H+ and HCO3-. Since H+ is a strong acid, HCO3- must be a weak conjugate base; unless my memory fails me completely 🙂
Click to expand...

HCO3- is an anion of a weak acid. The Na+ is a cation of a strong base. So dissolving it in water makes it basic. I forgot why, but that's the rule.
 
sugar is neutral. So pH of sugar water should just be 7. The sweet taste is your nerve ending sensing the sugar on its receptor and is not pH related. There are multiple types of taste buds on your tongue, distributed by location. The sweet buds are on the anterior portion of the tongue, there by evolutionary design.

Sugar however can be converted to organic acid by multiple step oxidation, when the ring structure is broken. Prior to oxidation to acid, sugar can be oxidized to alcohol -- how wine comes to be.
 
Soda is acidic because of the carbon dioxide disolved into the water, as well as the citric acid for the tartness. BTW, ketchup works wonders for copper heatsink bases.



-Steve
 
Originally posted by: Mark R
A buffer is a substance (or mixture of substances) that resist a change in pH.
Click to expand...

usually a weak acid (or weak base), when it is "overpowered" by a stronger acid it acts like a base and brings the solution back to a given pH, when you add base it acts like any other acid and neutralizes it. Basically (hah) it just hovers around a given pH level. Vital in biochemical reactions.

Originally posted by: George Powell

In fact cola is a great degreaser. It is also a great way of cleaning stickers off glass and plastics. Just as effective and cheaper than industrial alternatives
Click to expand...

yeah, but then it leaves the surface as sticky as the theater floor...😉
 
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