Dev chemisty ratios make my head hurt (aka, help with math!)

[f/stopblues]

Okay, I'm tired of trying to wrap my brain around this math problem. I'm diluting HC110 and this is only the second time I've used this stuff. I failed to realize that you have to dilute the concentrate to 1:3 for a stock solution, THEN further dilute for the A, B, C, etc..

So.. As it stands right now I have 1:7 with the concentrate (75ml HC110: 525ml water). I need a final dilution of 1:31 for dilution B, with 600ml total volume.

Help? Thank you! :bang: :bang: :bang:

 

[GeneW]

You're making it more difficult than you need to. Forget about stock solution. Mix directly from syrup as per these amounts from Covington's excellent HC-110 site:


http://www.covingtoninnovations.com/hc110/

Dilution 240 mL 300 mL 480 mL 600 mL
from (1 roll, (1 roll, (2 rolls, (2 rolls,
SYRUP steel plastic steel plastic
tank) tank) tank) tank)

A (1:15) 15 mL 18.8 mL 30 mL 37.5 mL

B (1:31) 7.5 mL 9.4 mL 15 mL 18.8 mL

C (1:19) 12 mL 15 mL 24 mL 30 mL

D (1:39) 6 mL 7.5 mL 12 mL 15 mL

E (1:47) 5 mL 6.3 mL 10 mL 12.5 mL

F (1:79) 3 mL 3.8 mL 6 mL 7.5 mL

G (1:119) 2 mL* 2.5 mL* 4 mL* 5 mL*

H (1:63) 3.8 mL 4.7 mL 7.5 mL 9.4 mL

Gene

 

[f/stopblues]

That's a good reference Gene, thank you. I'll use it in the future. The problem is that I already mixed it 1:7, so I'm trying to figure how to use it without starting from scratch.

 

[paulfitz]

this is one of those questions that I should be able to answer, since I used to get tested on it all the time.

Shouldn't the final be 1:21? If you are supposed to take a 1:3 stock and dilute the 1:3 stock at 1:7 then the final is 1:21 (3 x 7) of the original solution, not 1:31.

I've never used hc-110, but I am pondering your brain teaser. The answer lies probably in doing the reverse - dillute the now "stock" 1:7 at a 1:3 ratio. So you just have to think like you made a bigger batch. if you needed a 1:21 ratio and have 75ml of concentrate you would add 75ml of concentrate to (21 x 75) to 1575 ml of water. So if you bring the total volume of the current solution to 1650ml (75 + 1575) then the HC110 would be at the correct dilution in the larger volume. Then you have to draw off what you need to work with.

Problem is that you probably don't want to make the whole thing a working solution for shelf life reasons.

So I am still pondering. Perhaps another member more familiar with HC-110 can check my math and logic.

 

[paulfitz]

now I recall it - this is the HC-110 dilution B. According to the post by GeneW, it says that dilution b is 1:31 and I checked the data sheet from Kodak and it says 1:31. So if you started with 75ml of syrup you would have had to add it to 2325ml (75 x 31) of water to give a final volume of 2400ml. So if you bring the final volume of your current 600ml to 2400ml then the 75ml will be at the correct dilution. This is also consisten with the 7.5 ml in a total volume of 240 ml.

I believe this is essentially 1:3 of what you have now. 600ml +1800 (3 x 600)ml = 2400ml. So I believe you could take 150ml of the current "wrong stock" and add it to 450ml of water to get 600ml working volume and be at the correct dilution and get what you want.

Another way to look at it is that the 150ml will contain 8 parts (1 HC110 and 7 water) so each part is 18.75ml (150/8). 18.75 x 31 = 581.25. So 18.75 syrup at 1:31 gives 600ml (18.75 + 581.25). This is consistent with GeneW posting.

But somebody should check my math and logic! It's sunday and I have only had two cups of coffee so far!

 

[richard_l]

paulfitz is correct: 150ml of your 1:7 dilution + 450ml water.