Question 1
Study the information given below and use it to answer the questions that follow;Red dye is more soluble than green dye, green is more soluble than yellow whereas blue dye is the least soluble.
i) Represent the three dyes on a round paper chromatography
ii) Name one industrial application of chromatography
Answer
i)
ii) Detecting/identifying poisonous substances present in food substances// purifying natural pigments
ii) Detecting/identifying poisonous substances present in food substances// purifying natural pigments
Question 2
a) What is a fuel
b) Calculate the heat value of ethanol if its molar enthalpy of combustion is-1360kjmol-1(C=12.0, O=16.0, H=1.0)
Answer
a) A substance that produces a substantial amount of energy when burnt
b)
b)
Question 3
Study the set up below and use it to answer the questions that follow
a) What physical property of calcium metal is demonstrated in the diagram above
b) What would be observed if water was replaced with dilute Sulphuric (VI) acid
Answer
a) Denser than water
b) Effervescence/gas bubbles which stops immediately // white precipitate with evolution of gas bubbles/effervescencesCalcium reacts with sulphuric acid to form an insoluble calcium sulphate and hydrogen gas
b) Effervescence/gas bubbles which stops immediately // white precipitate with evolution of gas bubbles/effervescencesCalcium reacts with sulphuric acid to form an insoluble calcium sulphate and hydrogen gas
Question 4
A hydrocarbon decolorizes chlorine gas in presence of ultra violet light but does not decolorize acidified potassium manganate (VII) solution.
i) Name the homologous series to which the hydrocarbon belongs
ii) Draw the structural formula and name the fourth member of the homologous series to which the hydrocarbon belongs?
Answer
i) Alkanes
ii)
ii)
Question 5
Explain why a solution of hydrogen chloride in water turns blue litmus paper red but a solution of hydrogen chloride in methylbenzene has no effect on litmus papers
Answer
HCL(g) ionizes in water to form acidic solution while in methylbenzene, HCl(g) gas remains molecular hence neutral