Food Science 101

Hi coffeebean,

A mole of a chemical compound is its molecular weight in grams.

Table salt is NaCl - one atom of sodium (MW = 23.0 g/mole) and one atom of chlorine (MW = 35.5 g/mole). Therefore, the molecular weight of NaCl is 58.5 g/mole.

If there is 10 millimoles (0.01 moles) of sodium per liter, there is 0.01 x 23.0 = 0.23 g/L of sodium.

To represent NaCl concentration, divide the sodium concentration by the weight fraction of sodium in the molecule.

The weight fraction of sodium in the molecule = 23.0 g/mole/58.5 g/mole = 0.393. Then 0.23g Sodium divided by 0.393 = 0.585 g NaCl per Liter.

(Somebody check my work, I'm a little rusty)

Mike

Much obligued, Mikerho.

Your previous correspondent is correct. Another way of looking at it is by considering the balanced chemical equation.

Na⁺ + Cl^- = NaCl

This says that 1 mole of Sodium ions could in theory combine with 1 mole of Chloride ions to give 1 mole of Sodium Chloride.

So in 1 litre you have 10 mmole of Sodium ions which could in theory combine with 10 mmole of Chloride ions to give 10 mmoles Sodium Chloride.

Atomic Weight Sodium = 23 Atomic Weight Chlorine = 35.5

Molecular Weight NaCl = 23 + 35.5 = 58.5

So 10 mmoles NaCl = 10 x 58.5 = 585 mg NaCl in 1 litre.

Coffeebean,

When you get time, you may want to look up "sugars" in wikipedia. Crystal sugar or table sugar is named sucrose, and is a dimer of glucose and fructose. You lose a water molecule when they form the dimer (2C₆H₁₂O₆ = C₁₂H₂₂O₁₁ + H₂O). Within the accuracy of your question, then, 20g/L of glucose is nearly the same as 20g/L of sucrose. The human body perceives the sweetness of sugars differently, but my memory is that glucose and sucrose are fairly close while fructose is a noticeably "sweeter".

--JMM

Thanks. Now I get it.

Hi jmueller,

Right you are and GA. After I had posted, I realized I had not answered the second question. I meant to later, but got er sidetracked!

Mike

As Sucrose hydrolyzed to form glucose and fructose in the body (we don't utilize sucrose in our bodies) you could calculate the glucose equivalency. The only thing would be to figure out the glucose equivalency for fructose. For every mole of sucrose you have 1 mole glucose and 1 mole fructose. For the glucose the molar weight is 180 grams per mole. Since Fructose has a much lower glycemic index (19), the glucose equivalence in the human body in this aspect differs substantially, in other aspects it would also differ based on the metabolic process it is involved in. You would have to specify the metabolic process it is being considered as equivalent for glucose.

My original question on sodium and glucose deals with attempting to come up with a economical, canteen-made isotonic drink targeted for work crews toiling on sugar cane fields on 35-38°C and 80% RH whether. The key word is isotonic, not just any commercial hidrating concoction. My understanding is that Powerade or Gatorade are not isotonic in the strict sense of the term and besides they´d be too expensive to use. I´ve able to learn more on the issues through your contribution and the web. So thanks very much to all of you who have pitched in on this post.

Coffeebean,

My parents were a chemist and a nutrition/diet-therapist. I remember well my mother's complaining about the researchers at the university in Florida patenting their research into fluid/electrolyte replacement drinks. It seems that this was funded by money from government grants. It was an early example of public monies being converted to private gain. I don't know if their research data are available in any easily-accessed form today. I strongly suspect that the formulae they experimented are much cheaper than the market price for the product that was patented and sold.

--JMM