Study the flow chart and answer the questions. Identify gases P and T and state conditions for fermentation.

b) Study the flow chart below and answer the questions that follow.

i) State the conditions necessary for fermentation of glucose to take place.
The conditions necessary for fermentation of glucose are:

• Presence of yeast (which contains enzymes like zymase).
• Anaerobic conditions (absence of oxygen).
• A suitable temperature, typically around $37^\circ\text{C}$.

ii) State one reagent that can be used to carry out process S.
Process S is the oxidation of ethanol to ethanoic acid.
One reagent that can be used is acidified potassium dichromate(VI) ($\text{K}_2\text{Cr}_2\text{O}_7/\text{H}^+$) or acidified potassium permanganate(VII) ($\text{KMnO}_4/\text{H}^+$).

iii) Identify gases P and T.

• Gas P is formed from ethanol using concentrated $\text{H}_2\text{SO}_4$, which is a dehydrating agent. Ethanol dehydrates to form ethene ($\text{CH}_2=\text{CH}_2$).
• Gas T is formed from sodium ethanoate using dry sodium hydroxide. This is a decarboxylation reaction, producing an alkane with one less carbon atom. Sodium ethanoate produces methane ($\text{CH}_4$). Therefore, Gas P is $\boxed{\text{Ethene}}$ and Gas T is $\boxed{\text{Methane}}$.

iv) How is sodium hydroxide kept dry during reaction?
Sodium hydroxide is kept dry by mixing it with calcium oxide ($\text{CaO}$) to form soda lime. Calcium oxide acts as a drying agent.