Naked Science Forum
On the Lighter Side => Science Experiments => Topic started by: kyleglanville on 09/09/2012 22:34:04

Hi, (sorry for posting twice: I thought my first one may be in the wrong section!)
A slightly different type of question I would assume!
If I mix 500ml of 37.5% vol vodka (which I believe weighs 1220g) with 200g of pick n mix sweets so that all of the sweets dissolved completely into the vodka, what would the new alcoholic content of the vodka be?
In my head I have it that:
1220g of vodka (@ 37.5% vol)
+
200g of sweets (@ 0%vol)
=
1420g of mixed vodka and sweets
Therefore: 1220 / 1420 = 0.859 (3 s.f.)
0.859 * 37.5 = 32.2 (3 s.f.)
New concentration of mixed vodka and sweets = 32.2% vol (3 s.f.)
Is this correct please? Thank you!

Keep in mind that you are doing percent volume, rather than percent weight.
Here you are assuming that 1 gram of anything = 1 ml.
That is close...
However, the density of Ethanol is .789 g/cc, rather than 1 g/cc.
Hmmm
500ml of vodka will have to weigh less than 500ml of water, so it would have to weigh less than 500g. Somewhere the 1220g must be wrong. Did you weigh the bottle?
Anyway, the first thing to do is to figure out how much water, and how much alcohol you have.
500ml * 0.625 = 312.5 ml (g) water.
500ml * 0.375 = 187.5 ml alcohol
187.5 ml * .789 g/ml = 147.9 g ethanol.
Total: 312.5 g water + 147.9 g ethanol = 460.4 g solution.
Add 200g > 660.4 g solution.
WEIGHT Percent Ethanol = 147.9 g / 660.4 g = 22.4%
If you wanted to calculate volume percent, you would need to know the volume of the sweets in the solution.
The density of sugar is about 1.59 g/cm³. However, my guess is that the density in solution is closer to 2 g/cm³.
So, let's put in 100cm³ = 200g of sweets in solution as an estimate
From above:
312.5 ml (g) water
187.5 ml alcohol
500 ml solution.
Add 100 ml sugar (approx).
600 ml final solution (approx).
Volume Percent Ethanol 187.5 ml / 600ml = 31.2% (approx).

Spot on answer Clifford. I decided not to post my own reply after yours.

Spot on answer Clifford. I decided not to post my own reply after yours.
Nearly half a year after.

Spot on answer Clifford. I decided not to post my own reply after yours.
Nearly half a year after.
lol...