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Lorrainelovesplants	working out ABV Okay... having a maths argument with John. How to calculate ABV... If I have 20L of 10.92% and 20L of 8.3% and I mix them together, what is the ABV of the 40L? I make it 9.17%, but he insists that this is wrong as I have to work out the average differently..... anyone?
Rob R	I make it to be 9.61%
joanne	I make it 9.61% as well - add the two together & divide by 2 to get the ABV
sean	What they said. How did you get to your answer?
dpack	20l at 10.92=218.4gm 20 at 8.3=116gm so 384.4gm in 40l=9.61 % MAYBE?
dpack	tis a wt/volume calculation
Lorrainelovesplants	okay, Ill suggest its 9.61%, so as its quite high I could dilute down to around 6% by adding 20L water/juice? This would make a total volume of 80L... (yes, my maths is shite)
Bodger	Did you put sugar in with the apple juice before fermentation to get such a high reading?
Lorrainelovesplants	nope - all pure apple. My local small cider professional says to dilute half water and half juice, but Ill need to pasteurise it all or it will start again. and Ive just been given some redundant plastic 20L polypins, so I need to see how I can use these....
Bodger	We've found that cider of no more than 5% sells the best. Anything more than that and the majority of punters tend to look at it a bit suspiciously. That reading of 10% is hellishly high for a cider that hasn't had sugar added to it.
dpack	it might be interesting to try some
Lorrainelovesplants	The two pressings we did - first one (a mix of apples, mainly eaters) 1063 second one (ciders with loads of Cornish Aromatic) 1083. Remember weve had a really good hot summer. Bodger, the plastic cap/bung things on the top of a beer polypin (a plastic one, not a bag in box) what is it called? The bit that the pub screws into?
Bodger	If you mean poly barrel, I only know it as a top or cap.
Lorrainelovesplants	Just found out - its a keystone bung and they are not going to be good for storing finished cider, but could use for fermenting in small quantities.
fungi2bwith	Re: working out ABV Okay... having a maths argument with John. How to calculate ABV... If I have 20L of 10.92% and 20L of 8.3% and I mix them together, what is the ABV of the 40L? I make it 9.17%, but he insists that this is wrong as I have to work out the average differently..... anyone?

To get the exact answer, it should be pointed out that the question makes an incorrect assumption. Mixing two lots 20 litre liquids together which have different alcohol contents will not result in exactly 40 litres of liquid. Therefore, a simple average (mean) of the percentages will not give the correct result.
However, the difference will be minor and very difficult to calculate.

Lorrainelovesplants

Its fine - just a working calculation. Ill be getting it professionally tested. Smile

Bodger

Send me a sample, I'll put it through our fractometer. free of charge.

Nick

Re: working out ABV

Okay...
having a maths argument with John.

How to calculate ABV...

If I have 20L of 10.92% and 20L of 8.3% and I mix them together, what is the ABV of the 40L?
I make it 9.17%, but he insists that this is wrong as I have to work out the average differently.....

anyone?

I think for all practical purposes it does, but because of the sizes of the particles there is a teeny, tiny loss of volume. Like adding marbles to tennis balls.

http://chemistry.about.com/od/lecturenotesl3/a/miscibility.htm Nick

Right. gardening-girl

We have just bottled 38 pts of homebrew,10.10% on the hydrometer.
How do I work out the ABV please. sean

You need to know what the SG was at the start of fermentation as well as at the end, gardening-girl

Will see if the brewer made a note!

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