Chemistry 5070 · O Level · Formulae, functional groups and terminology

Formulae, functional groups and terminology — practice question

Plants are composed of many different kinds of carbon compounds.
(a)[3]

Photosynthesis is how plants produce carbon compounds. Write the overall equation for photosynthesis and state the conditions needed for this process.

(b(i))[1]

Starch is a polymer in plants, and it can be hydrolysed. Give the name of the substance formed when starch is hydrolysed.

(b(ii))[2]

State the reagent and the conditions required to hydrolyse starch.

(c(i))[2]

Ethanoic acid reacts with calcium hydroxide to produce a salt and water. Give the name and formula of the salt formed.

(c(ii))[1]

One ester in the distillate has the molecular formula $\text{C}_4\text{H}_8\text{O}_2$. Draw the structure of an ester with this formula, showing all the atoms and all the bonds.

(c(iii))[2]

The distillate also contains a compound with the following composition. Carbon 37.5%, hydrogen 12.5%, oxygen 50.0%. Deduce the empirical formula of this compound.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

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