Help With Chemistry!!!!

dancqu · Feb 28, 2005

Kirk Keyes said:
There is a continuum of pHs there that can be made, ...

R. Suzuki suggests sodium carbonate and the bicarbonate
for that purpose.

I believe most developing agents are acid and if the ratio
of the agent and other components is low it can pull the ph
quite low. I worked with an 8 and 80 gram D23. The sulfite
would not pull the ph above 7.8 +/- .1 and I've seen
sulfite peged at a ph of 9.8 by a supplier. Dan

Kirk Keyes · Feb 28, 2005

dancqu said:
I've got news for you and Mr. Qualls. Sodium sulfite has
a GREATER alkalinity than borax. One-shoters don't need
borax. The borax is there to absorb OH ions produced
by the oxidation of hydroquinone; ph maintanance.

The ph of bicarbonate and borax are nearly the same;
9 plus a tenth or two depending on the data you read.
The ph of sulfite runs above those two, up to
several tenths, also depending. While on the
subject of depending, who have you two
been reading? Maybe A & T? Dan

I just checked the pH of a 5g/100ml soultion of sodium bicarbonate, and I got pH 8.0. A freshly made solution of sodium sulfite at 5g/100ml was pH 10.0.

I've never tried to titrate sodium sulfite solutions, so I'm not sure about the claim made here about it having a higher alkalinity than borax.

Maine-iac · Mar 2, 2005

jim appleyard said:
Could you share this D-23C formula with us?

I'll sort through my box of formulas later tonight and try to find it.

dancqu · Mar 2, 2005

Kirk Keyes said:
I just checked the pH of a 5g/100ml soultion of sodium bicarbonate,
and I got pH 8.0. A freshly made solution of sodium sulfite at
5g/100ml was pH 10.0.

I've never tried to titrate sodium sulfite solutions, so I'm not sure
about the claim made here about it having a higher alkalinity
than borax.

Not sure? You say the sulfite measured ph 10.0. I've measured
borax 1% at 9 and I see via the WWW 9.18 mentioned.

I've measured bicarboate, also 1%, at 9 but think that may be
atypical or an error on my part; 8.2 is indicated. Dan

Kirk Keyes · Mar 2, 2005

dancqu said:
Not sure? You say the sulfite measured ph 10.0. I've measured
borax 1% at 9 and I see via the WWW 9.18 mentioned.

I've measured bicarboate, also 1%, at 9 but think that may be
atypical or an error on my part; 8.2 is indicated. Dan

Perhaps your bicarbonate was either not high quality (i.e. it may have had some carbonate in it), or, as you say, was an error on your part. Can't really speculate without more info.

A 50/50 solution of carbonate/bicarbonate should have a pH of 8.3, as I said below. That fact is routinely used to calculate the concentration of each componant of a solution containing carbonate species. If you have a pH below 8.3, you have more bicarbonate, if the pH is above 8.3, you have more carbonate.

See "Standard Methods for the Examination of Water and Wastewater", any edition, Method 2320, Parts A and B. It's a nationally approved method for determining the alkalinity of a solution.

dancqu · Mar 3, 2005

A 50/50 solution at what concentration? Water and Wastewater,
that could parts per million and not very many parts. A 1% solution
is 10,000 parts per million. That's not milligrams per liter that's grams
per liter.

Bicarbonate of soda is a weak alkali and 8.2 IS weak. Dan

Maine-iac · Mar 3, 2005

jim appleyard said:
Could you share this D-23C formula with us?

Jim,

Here's the D-23C recipe I experimented with years ago. The first version is just ordinary D-23 with Vitamin C added.

D-23C

Water--1 liter
Metol-- 7.5g or 2 1/8 tsp.
Sulfite-- 100g or 4tsp. + 1tsp.
Ascorbic acid-- 1 g or 1/4 tsp.

In those days, before tabular grain films, I was mostly using HP5+ and FP4+. Try a starting time around 7 minutes at 70 degrees. You'll have to adjust that no doubt to find what's right for your film choice.

I found that the addition of the Vitamin C just made the developer more active.

Later, I experimented with decreasing the amount of sulfite to about 20g and it still worked fine, perhaps with some adjustment to times, though I don't remember clearly, and in those days of my omniscient youth, I didn't always need to write down notes to myself.

Since then, Pat Gainer has demonstrated that in Phenidone/C developers, sulfite is totally unnecessary. I don't know whether this holds true with Metol-based developers or not. Pat might want to chime in here and set us straight.

I also modified the replenisher D-25R by the addition of 1/4 tsp. Vitamin C as well and replenished as the D-23 instructions recommend. That worked well too.

I haven't used this for years, since I've switched to Phenidone/C exclusively now, but I remember being very satisfied with the quality of the negs I got.

The main principle, of course, is that Vitamin C is superaddititive with Metol (or vice versa) just as it is with Phenidone.

Larry

Jordan · Mar 3, 2005

dancqu said:
A 50/50 solution at what concentration? Water and Wastewater,
that could parts per million and not very many parts. A 1% solution
is 10,000 parts per million. That's not milligrams per liter that's grams
per liter.

Bicarbonate of soda is a weak alkali and 8.2 IS weak. Dan

Kirk is referring to a carbonate buffer system in which equal concentrations (in molar terms) of carbonate and bicarbonate give a pH of 8.3. It does not matter what the concentration of the two species are, as long as they are equal. This is one of the properties of buffer systems. They can be diluted and maintain their pH (although not their buffering "capacity").

Incidentally, I believe that the carbonate-bicarbonate system is what the body uses to regulate the pH of blood. It is intimately tied to the regulation of CO2 in the blood, etc.

gainer · Mar 3, 2005

Maine-iac said:
Jim,

Here's the D-23C recipe I experimented with years ago. The first version is just ordinary D-23 with Vitamin C added.

D-23C

Water--1 liter
Metol-- 7.5g or 2 1/8 tsp.
Sulfite-- 100g or 4tsp. + 1tsp.
Ascorbic acid-- 1 g or 1/4 tsp.

In those days, before tabular grain films, I was mostly using HP5+ and FP4+. Try a starting time around 7 minutes at 70 degrees. You'll have to adjust that no doubt to find what's right for your film choice.

I found that the addition of the Vitamin C just made the developer more active.

Later, I experimented with decreasing the amount of sulfite to about 20g and it still worked fine, perhaps with some adjustment to times, though I don't remember clearly, and in those days of my omniscient youth, I didn't always need to write down notes to myself.

Since then, Pat Gainer has demonstrated that in Phenidone/C developers, sulfite is totally unnecessary. I don't know whether this holds true with Metol-based developers or not. Pat might want to chime in here and set us straight.

I also modified the replenisher D-25R by the addition of 1/4 tsp. Vitamin C as well and replenished as the D-23 instructions recommend. That worked well too.

I haven't used this for years, since I've switched to Phenidone/C exclusively now, but I remember being very satisfied with the quality of the negs I got.

The main principle, of course, is that Vitamin C is superaddititive with Metol (or vice versa) just as it is with Phenidone.

Larry

No need for sulfite in PC or MC. You may feel a need for it for some other reason, but I doubt you'll find any significant improvement in grain. Now, with PQ or MQ, you need a little sulfite for maximum synergism. Without it, PQ or MQ make staining developers somewhat akin to catechol but different color.

The amount you need with hydroquinone is only about the same weight as the hydroquinone. Not enough to have any effect on grain.

Kirk Keyes · Mar 3, 2005

dancqu said:
A 50/50 solution at what concentration? Water and Wastewater,
that could parts per million and not very many parts. A 1% solution
is 10,000 parts per million. That's not milligrams per liter that's grams
per liter.

Bicarbonate of soda is a weak alkali and 8.2 IS weak. Dan

Sorry Dan, I was talking about a ratio of 50/50, not some actual, particular concentration.

Water and wastewater does range from very low parts per million to percentage concentrations. The same principles apply to both situation.

"Bicarbonate of soda is a weak alkali and 8.2 IS weak."

Weak what - alkalinity? pH?

You seems to not understand some fundemental concepts of pH and alkalinity with that statement. It all depends on the concentrations.

The alkalinity of a water is an meaurement of the acid-neutralizing capacity of the water. You can easily make a solution that has a pH of 6 that has thousands of times more alkalinity and is a much stronger buffer than a solution that has pH of 13.

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