Grape juice has 180 g of sugar in each litre…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Grape juice has g of sugar in each litre. Yeast ferments all of the sugar and gives of the best possible yield.
- What mass of ethanol is made in each litre?
- What volume of ethanol is this?
- What is the strength of the wine, as the per cent of its volume that is ethanol? Take the wine as mL.
Need a reminder? The key ideaShow
Yeast ferments sugar to ethanol. The best possible yield is g of ethanol from g of glucose, and the density of ethanol is g per mL. Wine and beer are not distilled. Whisky, brandy and rum are. Citric acid: Aspergillus niger. Acetic acid: Acetobacter aceti. Butyric acid: Clostridium butylicum. Lactic acid: Lactobacillus.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Sugar: g in each litre. Yield: g of ethanol from g of sugar, at . Density of ethanol: g per mL.
Plan. Find the mass of ethanol, change it to a volume, then take the share of one litre.
Step 1. Mass. g.
Step 2. Volume. mL.
Step 3. Strength. by volume.
Answer: g; mL; .
Check. Table wines are about to per cent ethanol, so is a believable value.
Watch out. Mixing ethanol and water shrinks the volume a little, so a laboratory would measure a slightly different strength.
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