(a)(i) State the two types of hardness in water. (ii) Name a salt that causes each type of hardness. (ii) Write a balanced equation for the removal of each type of hardness. (iv) State one effect of hard water on soap.
(b)(i) State whether the pH of each of the following is less than, equal to, or greater than 7. I. Glucose solution II. Chlroine water III. Lime water IV. Sour milk (ii) Give the difference between the following compounds: I. an acidic oxide and an amphoteric oxide; II. concentrated acid and a dilute acid; Ill. a normal salt and an acid salt
(c)(i) Iron reacts with H\(_2\)SO\(_4\) according to the equation: Fe\(_{(s)}\) + H\(_2\)SO\(_{4(aq)}\) ---> FeSO\(_{4(aq)}\) + H\(_{2(g)}\) Calculate the mass of FeSO\(_4\) that would be produced by 0.5 mole of Fe. [H = 1, S = 32, Fe = 56] (ii) List two allotropes of sulphur
(d)(i) State what would La observed when a damp starch-iodide paper is dropped into a gas jar of chloride (ii) Explain your ansv.er in (d)(i) above. (iii) State the products formed when ammonia reacts with excess chlorine.
Explanation
(a) i) Temporary hardness and permanent hardness. (ii) Temporary hardness — Calcium hydrogen rioxocarbonate IV or magnesium hydrogentrioxocarbonate(IV). Permanent hardness — Calcium etraoxosulphate (VI) or magnesium tetraoxosulphate (VI). Temporary hardness: iii) Ca(HCO\(_3\))\(_2\) + Ca(OH)\(_2\) \(\to\) 2CaCO\(_3\) + H\(_2\)O OR Ca(HCO\(_3\))\(_2\) \(\to\) CaCO\(_3\) + H\(_2\)O + CO\(_2\) Permanent hardness: CaSO\(_4\) + Na\(_2\)CO\(_3\) \(\to\) CaCO\(_3\) + Na\(_2\)SO\(_4\) (iv) It forms precipitate of calcium salt or ;cum with soap that waste soap.
(b)(i) 1. Glucose solution —Equal to 7 II. Chlorine water — Less than 7 II. Lime water — Greater than 7 IV. Sour milk — Less than milk. (ii) I. An acidic oxide reacts with only alkali to form salt and water only while amphoteric oxide react with both acids and alkalis to form salt and water only. II. A dilute acid contains more water than a concentrated acid. III. An acid salt contains replacement iydrcgen while a normal salt does not.
(c)(i) Fe\(_{(S)}\) + H\(_2\)SO\(_{4(aq)}\) \(\to\) FeSO\(_{4(aq)}\) + H\(_{2(g)}\) ; Molar mass of FeSO\(_4\) 56 + 32 + 64 = 152 1 mole of Fe produces 152 mass of FeSO\(_4\) ; 0.5 mole of Fe will produce \(\frac{0.5 \times 152}{1}\) = 76g ii) Monoclinic and rhombic sulphur
(d)(i) When a piece of damp starch - iodide paper is plunged in a gas ar of chlorine, the paper turns from white to blue or blue black. (ii) Chlorine displaces iodine from starch odide. The iodine reacts with starch to form a blue black complex. (iii) Products formed are hydrogen Chloride and nitrogen.
