2012 Chemistry Neco Theory Questions

(a) A carbohydrate P contains 40% carbon. 6.67% hydrogen. If P has a relative molecular mass of 60, determine its;

i. Empirical formula

ii. Molecular formula [H=1, C= 12, O=16]

(b) An alkanoic acid Q has a relative molecular mass of 74;

i. what type of reaction is involved when Q is converted to an alkanoate?

ii. write the structural formula of Q

iii. Write an equation for the reaction between Q and sodium

iv. If P in (a) above boils at 188 and belongs to the homologous series as Q, state with reasons whether the boiling point of Q will be equal to, higher or lower than 118.

(c) (i)  State THREE differences between  covalent and electrovalent compounds

(ii) Give THREE chemical properties of   metals

(a)  (i)     What is fermentation

(ii)     Write an equation for the fermentation of starch

(iii)   Explain why a tightly corked glass bottle .       filled to the brim with fresh palm wine  shatters on standing for some time

(iv)   Define the term allotropy

(b)  (i) State Graham’s law of diffusion.

(ii) A given mass of gas occupies 850cm³ at    320K and 0.92×10⁵Nm^-2 pressure. Calculate the volume of the gas at standard temperature and pressure. [Pressure at s.t.p = 101325Nm^-2]

(iii) Give the natural sources of the following organic acids

–  Lactic acid

–  Ascorbic acid

– Amino acid

(c)  (i)   What is an acid?

(ii)  Give THREE general methods of prep. salt

(i) What is an anhydride?

(ii)           Give ONE example in b(i) above

(iii)          Give THREE chemical properties of hydrochloric acid

b. (i) State THREE physical properties of chlorine

(ii) Write an equation for the rxn btwn. Chlorine      and:

a. Iron (II) Chloride

b. Hydrogen Sulphide

c. If a certain mass of hydrogen gas collected over water at 27 and 727mmHg has a volume of 1729cm³ . Calculate the volume of the dry gas at S.T.P. (S.V.P of water at 27C=27mmHg)

d. (i) Give THREE uses of sodium trioxocarbonate (IV)

(ii) Give the IUPAC names of the following salts: AgNO₃ , Pb(NO₃)₂, CoCl₂ and Mg(No₃)₂

(a) (i) State LeChatelier’s principle.

(ii) State THREE conditions that affects equillibrium

(iii) Mention TWO characteristics of catalyst

(iv) When a radioactive element emits alpha   particle , state what happens to its

i. Mass number

ii. Atomic number

(v) List TWO uses of radioisotopes

(b) (i) Mention THREE types of iron

(ii) Define rusting

(iii) Mention ONE way of preventing rusting of iron.

(c) (i) Define the term hygroscopy

(ii) Mention TWO examples of efflorescent substances

(iii) Calculate the oxidation number of N in       Mg (NO₃)₂

(a) (i) Define the following terms:

i. Ion

ii. Electrolyte

(ii) State the TWO laws of electrolysis.

(iii) Calculate the volume of oxygen evolved at 294 K if a current of 3.5 A is passed through acidified water for 1.8 minutes [molar volume of a gas  is 22.40dm³, 1 Faraday = 96500C]

(b) (i) Define a standard solution.

(ii) Give ONE difference between a compound and a mixture

(iii)  Classify each of the following as a compound or a mixture

i.  Sugar

ii.  Blood

iii.  Salt Water

State the law of conservation of mass

a. (i) What is a hydrocarbon?

(ii) Mention any THREE classes of hydrocarbons giving a named example in each case.

b. (i) Write the IUPAC name of the following compounds.

I. [(Cu(NH₃)₄]²⁺

II. [(Fe(CN)₆]^3-

III. Cr₂O

(ii) Solution A is 0.10mol dm^-3 HCl. B is a solution of sodium trioxocarbonate (IV), 25cm³ of B is titrated against A using methyl orange as indicator. 23.5 cm ³ of A is used in titration.

Calculate the mass of sodium trioxocarbonate (IV) present in one dm³ of the solution B.         [Na = 23,  C=12,  O=16 ]

c. (i) What is an isotope

(ii) Consider the following compounds: CaO, CaCO₃, Ca(OH)₂ and NaOH. Which of them is

i. Used in the manufacture of cement

ii. Used to detect the presence of carbon(IV)oxide?

iii. Used to liberate carbon(IV)oxide when dilute acid is added to it?

iv. Hygroscopic

v. Deliquescent