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Specific weight of dextrose?

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gregsky

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I have a 5lb bag of dextros I want to use to prime, but I dont have a scale and I dont know how to measure out 4-5oz. Is there a known ratio between the volume in cups to the weight in lbs?
 

Jesse17

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Here's your google welfare check...

There is 28.35 g in one oz (weight), so if you want 4 oz then you would want 113.4 g. (4 oz x 28.35 = 113.4 g.)

According to wikpedia, dextrose/glucose weighs 1.54 g cm³.

There's 29.57 cm³ per oz. (volume) so to if you multiply 1.54 g x 29.57 you get 45.54. This means that dextrose weighs 45.54 g. per oz (volume).

Therefor, if you want 4 oz (weight) which equals 113.4 g. then you would divide your (desired amount of dextrose in g.) by the (weight in g. per oz. in volume) to find how many oz (volume) of dextrose to use. (113.4 / 45.54 = 2.49 oz. (volume))

8 oz. (volume) per cup means that 2.49 oz. = 0.311 cups which is about 1/3 C. of dextrose = 4 oz (weight)

Or 141.75 / 45.54 = 3.112 oz. (volume) = 0.389 cups dextrose = 5 oz (weight).

I don't know what size batch you're doing, but you usually use 3/4 C dextrose for a 5 gal. batch. So one of three things is happening here. 1. I messed up on my math, 2. You're doing a 2.5 - 3 gal. batch, or 3. 4-5 oz. dextrose isn't enough priming sugar.

Hope this helps ya out.
 

Jesse17

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Just measured the 4.5 oz "priming sugar" pack from AHB which I'm assuming is dextrose, and it was 3/4 C.

So my math or sources must be messed up somewhere on my previous post.
 

Scimmia

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Jesse, it's probably because your calculations may be correct for a solid block of dextrose. There's going to be quite a bit of air in what we use.

Ironically, that also means that 3/4 cup of one form of dextrose won't be the same as 3/4 cup of another. I've seen some that's almost as course as table sugar, and some that's more like powered sugar.
 

bradsul

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You can't really measure a compactable material by volume unless you know the density of the packed material you're measuring. Just go to a dollar store and get a cheap scale, close is good enough for priming sugar.

A scale is one of those really handy things in brewing, you might want to spend $20 or so and get a half decent one.
 

TexLaw

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bradsul said:
You can't really measure a compactable material by volume unless you know the density of the packed material you're measuring. Just go to a dollar store and get a cheap scale, close is good enough for priming sugar.

A scale is one of those really handy things in brewing, you might want to spend $20 or so and get a half decent one.
+1!


TL
 

BeerCanuck

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I remember weighing out 1 KG of dextrose for an extract recipe. I poured the 1 KG of dextrose into a measure jar ~ 1.5 litres . Knowing that 1.5 litres of dextrose is ~1 KG 750 ml should be ~1/2 KG. Same general principal for measuring should apply with dry malt extract as well (weigh once / find volume / do math :)

Cheers
BeerCanuck
 

Joker

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Jesse17 said:
Here's your google welfare check...

There is 28.35 g in one oz (weight), so if you want 4 oz then you would want 113.4 g. (4 oz x 28.35 = 113.4 g.)

According to wikpedia, dextrose/glucose weighs 1.54 g cm³.

There's 29.57 cm³ per oz. (volume) so to if you multiply 1.54 g x 29.57 you get 45.54. This means that dextrose weighs 45.54 g. per oz (volume).

Therefor, if you want 4 oz (weight) which equals 113.4 g. then you would divide your (desired amount of dextrose in g.) by the (weight in g. per oz. in volume) to find how many oz (volume) of dextrose to use. (113.4 / 45.54 = 2.49 oz. (volume))

8 oz. (volume) per cup means that 2.49 oz. = 0.311 cups which is about 1/3 C. of dextrose = 4 oz (weight)

Or 141.75 / 45.54 = 3.112 oz. (volume) = 0.389 cups dextrose = 5 oz (weight).

I don't know what size batch you're doing, but you usually use 3/4 C dextrose for a 5 gal. batch. So one of three things is happening here. 1. I messed up on my math, 2. You're doing a 2.5 - 3 gal. batch, or 3. 4-5 oz. dextrose isn't enough priming sugar.

Hope this helps ya out.

 

homebrewer_99

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bradsul said:
You can't really measure a compactable material by volume unless you know the density of the packed material you're measuring. Just go to a dollar store and get a cheap scale, close is good enough for priming sugar.

A scale is one of those really handy things in brewing, you might want to spend $20 or so and get a half decent one.
You're right Brad. I wasn't taking into account that some people compact when measuring...I'm not a compacter...:D
 

JarsOPorter

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You know, if you're really averse to buying a scale, you could measure length, width, height of your 5lb bag of dextrose and get a rough estimate of that particular bag's specific density. It'd be (rho) = (80oz)/(LxWxH).

Or you could get more precise, transfer your dextrose to an airtight canister, and fill the empty bag with something non-compressible (water, if the bag is plastic), and measure that. (rho) = (80oz)/(water volume).

It's way more trouble than buying a scale, though...
 

unionrdr

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To split hairs, you'd also have to take into account moisture content of the dextrose. This can alter the weight & thus volume. I got a digital scale in the Walmart kitchen needs isle for 20 bucks. makes life easier with grains, hops, sugars, extracts, etc...
 

Nubiwan

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To split hairs, you'd also have to take into account moisture content of the dextrose. This can alter the weight & thus volume. I got a digital scale in the Walmart kitchen needs isle for 20 bucks. makes life easier with grains, hops, sugars, extracts, etc...
Would we then need to factor for moisture weight? Runs for the hills........ :ban:
 
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