(a) A compound X reacts with excess HNO(_{3(aq)}) to give carbon (IV) oxide and another compound Y. A solution of Y reacts with NaOH(_{(aq)}) to form a white precipitate which is insoluble in excess NaOH(_{(aq)}). Identify X and Y.
(b) (i) Write a balanced equation to illustrate the reducing property of ammonia in its reaction with CuO.
(ii) Explain why it is not advisable to heat ammonium dioxonitrate (III) directly.
(iii) Give two uses nitrogen.
(c) Give the reason why (i) dilute H(_{2})SO(_{4}) is not suitable for the preparation of CO(_{2(g)}) from CaCO(_{3(s)}) (ii) concentrated H(_{2})SO(_{4}) cannot be used to dry ammonia gas.
(d) State two: (i) physical properties; (ii) chemical properties of metals.
(e) What is the oxidation number of: (i) chlorine in I. Cl(_{2}). II. ClO(_{-(3)})
(ii) vanadium in V(_{2})O(_{5})
(f)(i) Explain the term half-life. (ii) Two radioactive elements, P and Q have half-life of 1200 seconds and 3600 seconds respectively.
I. Which of the elements is more stable? II. Give a reason for your answer.
Explanation
(a) X — CaCO(_3) Y — Ca(NO(_3))(_2)
(b)i) 2NH(_{3(g)}) + 3CuO(_{(s)}) (to) 3Cu(_{(s)}) + 3H(_2)O(_{(g)}) + N(_{2(g)})
(ii) *Explosion may occur. *Because ammonium dioxonitrate (Ill) is unstable and decomposes exothermically.
(iii) *Manufacture of NH(_3) etc *liquid nitrogen as cooling agent * gas carrier in gas chromatography * as preventive against oxidation.
(c)(i) Dilute H(_2)SO(_4) reacts with CaCO(_{3(s)}) to form our insoluble salt CaSO(_4), which covers the CaCO(_3), thus preventing further reaction or production of CO(_{2(g)}) , after a short time. (ii) Conc. H(_2)SO(_4) reacts with ammonia to form a salt (NHq)(_2)SO(_4)
(d)i) Physical Properties of Metals * / ductility *Good conductor of heat / electricity *Sonorous *relatively high density * high melting / boiling points
(ii) Chemical Properties of Metals * Ionize by electron loss / reducing agent *Form basic oxides *(some) displace hydrogen from dilute oxide *A more reactive metal displaces or loss reactive metal from a solution cf its salt.
(e)(i) (I) Oxidation no of CI = 0
(II) Oxidation no of CI = + 5
(ii) Oxidation no of V = + 5
(f)(i) Half – life is the time taken for half of the total number of atoms in a given sample of the element to decay.
(ii)(I) Q is more stable
(II) Stability is dependent on half life, the longer it takes substance to decay the more stable it is.