A baker adds 4.5 g of glucose to a dough…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A baker adds g of glucose to a dough. The yeast ferments all of it by . The molar mass of glucose is g per mol. The dough is at and the pressure is atm.
- How many moles of glucose are fermented?
- How many moles of carbon dioxide are made?
- What volume does this gas fill? Use K.
Need a reminder? The key ideaShow
Lactic acid bacteria (Lactobacillus) ferment lactose to lactic acid and set milk as curd. Baker's yeast, Saccharomyces cerevisiae, ferments sugar to ethanol and carbon dioxide: . Swiss cheese has holes from the carbon dioxide of Propionibacterium. Roquefort cheese is ripened by a fungus. A bacterium that divides every minutes doubles its number times in each hour. For a gas, with L atm per mol per K.
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. Glucose: g. Molar mass: g per mol. K, atm.
Plan. Find the moles of glucose, then of carbon dioxide, then use the gas law.
Step 1. Glucose. mol.
Step 2. Carbon dioxide. The equation gives mol for each mole of glucose. mol.
Step 3. Volume. L.
Answer: mol; mol; L.
Check. At room temperature one mole of gas fills about L, so mol fills about L.
What if? At ( K) the same gas fills L. The ethanol made is g, which mostly evaporates in the oven.
Watch out. In a real dough some of the gas dissolves in the water of the dough, and only part of the sugar is fermented, so the dough rises less than this.
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