(i) Draw and label an energy profile diagram of an endothermic reaction. Indicate on your diagram the I. activation energy II. heat change, \(\Delta\)H.
(ii) Explain how the rate of reaction is affected by I. addition of a catalyst, II. increase in temperature.
(b)(i) Write an equation for the thermal decomposition of calcium trioxocarbonate (IV)
(ii) Determine the volume of carbon (IV) oxide measured at s.t.p. that would he produced by the thermal decomposition of 10g calcium trioxocarbonate (IV). [ Ca = 40; O = 16; C = 12 ]
(c)(i) Give one use cf each of the following forms of carbon: I. coal; II. wood charcoal; Ill. carbon (IV) oxide.
(ii) Write a balanced chemical equation to show what happens when each of the following compounds is heated strongly: I. NaNO\(_{3(s)}\) II. MgCO\(_{3(s)}\).
(d) Consider the following compounds: CaO, CaCO\(_3\), Ca(OH)\(_2\), 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;
(iv) hygroscopic;
(v) deliquescent?
Explanation
(1) (a)
(ii) I. Catalyst increases the rate of the reaction cy cowering activation energy.
II. The rate of reaction increases with increase in temperature because there will be more effective collisions.
(b)(i) CaCO\(_{3(S)}\) \(\to\) CaO\(_{(s)}\) + CO\(_{2(g)}\)
(ii) Molar mass of CaCO\(_2\) = 40 + 12 + 16 x 3 =100
From the equation in b(i) above,
100g of CaCO\(_{(3)}\) produces 22.4 dm\(_3\) of CO\(_2\) at s.t.p
10g of CaCO\(_3\) will produce \(\frac{10 \times 22.4}{100}\)
= 2.24dm\(^3\) of CO\(_2\)
(c)(i) I. Coal is used as fuel
II. Wood charcoal is used for absorbing poisonous gases
Ill. CO\(_2\) is used in the following:
— in fire extinguishers
—manufacture of washing soda by solvay process
— in carbonated drinks.
(ii) I. 2NaNO\(_{3(s)}\) ---> 2NaNO\(_{2(s)}\) + O\(_2\)
II. MgCO\(_{3(s)}\) \(\to\) MgO\(_{(s)}\) + CO\(_{2(g)}\)
(d)(i) CaCO\(_3\) — cement
Ca(HO)\(_2\) — detection of CO\(_2\)
CaCO\(_3\) — liberates CO\(_{2}\) with addition of acid
CaO — hygroscopic
NaOH — deliquescent.