6 (a) Write equations, including state symbols, to show the enthalpy change of formation of (i) methylamine, CH3NH2(g) (ii) potassium carbonate, K2CO3(s) (iii) propan-1-ol(1), CH3CH2CH2OH(1). (b) The standard enthalpy change of combustion of C(s), H₂ (g) and CH3 NH2 (g) are -394, -286 and -1085 kJ mol respectively. Calculate the standard enthalpy change of formation of methylamine.

The hydrocarbons acetylene (C2H2) and benzene (C6H6)have the same empirical formula. Benzene is an “aromatic”hydrocarbon, one that is unusually stable because of its structure.(a) By using data in Appendix C, determine the standardenthalpy change for the reaction 3 C2H2(g)-----> C6H6(l).(b) Which has greater enthalpy, 3 mol of acetylene gas or1 mol of liquid benzene? (c) Determine the fuel value, inkJ/g, for acetylene and benzene.

(a) Calculate the standard enthalpy change for the combustion of 1 mol of benzene, C6H6(l), to CO2(g) and H2O(l).(b) Compare the quantity of heat produced by combustion of 1.00 g propane with that produced by 1.00 g benzene.

The enthalpy changes accompanying the dissociation of successive bonds in NH3(g) are 460, 390, and 314 kJ mol-1 , respectively. (a) What is the mean enthalpy of an N-H bond? (b) Do you expect the mean bond internal energy to be larger or smaller than the mean bond enthalpy? (c) Use these values,along with tabulated bond enthalpies for the N-N and H-H bonds to estimate the standard enthalpy of formation of gaseous ammonia, NH3 , at 298 K.

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2. An experiment was carried out to determine the enthalpy change of combustion of propan-1-ol. The experimental set-up was shown below. a beaker water (500.0 cm³) propan-1-ol (a) Write the equation for the complete combustion of propan-1-ol (C;H¬OH). (b) Give a suggestion to the above set-up so as to minimize heat loss to the surroundings. (c) Burning 2.88 g of propan-1-ol caused the temperature of 500.0 cm³ of water to rise by 46.0°C. Calculate the enthalpy change of combustion of propan-1-ol. (Assume that the specific heat capacity and the density of water are 4.2 J g- K-l and 1.0 g cm- respectively.) (Molar mass of propan-1-ol: 60 g) -3 (d) The enthalpy change obtained in (c) cannot be called as 'standard enthalpy change'. Explain why.

(b) An aqueous solution of acetic acid can be prepared by the reaction of ethanol with oxygen : CH3CH2OH (1) + O2 (g) –→ CH3COOH (1) + H2O (1) Write thermochemical equations for enthalpy of formation of the given compounds and calculate AH for the reaction, given the following data. Enthalpy of formation, AHf (kJmol") -277.8 Compound CH;CH2OH (1) CH3COOH (I) H2O (1) -485.0 -286.0

Sucrose, C12 H22011, is common table sugar. The enthalpy change at 25°C and 1 atm for the complete burning of 2 mol of sucrose in oxygen to give CO2(9) and H2O(1) is - 1.128 x 10* k. From this and from data given below: AH (H2O(1) = -285.8 kJ/mol AH (CO2(9)) = -393.5 kJ/mol AH (O2(9) = 0 kJ/mol Calculate the standard enthalpy of formation of sucrose. AH; =| K/mol

2 (a) In this investigation, you will use a polystyrene-cup calorimter to determine the amount of heat released during acid-base neutralization reactions. Find information in your textbook, an encyclopedia, or a web site about calorimetry. Sketch the apparatus for a polystrene-cup calorimeter. (b) For more precise heat of reaction measurnments, chemists use a device called bomb calorimeter. How is a bomb calorimeter similar to and different from a polystyrene-cup calorimeter?

Q.29. Determine, at 298 K, ArH°, the standard enthalpy of the reaction (1) between dinitrogen tetraoxide and hydrazine: (1) N2O4 (g) + 2 N2H4 (1) → 3 N2 (g) +4 H2O (g) Knowing the standard reaction enthalpies, at 298 K. of the following reactions: (2) NH3 (g)→ 1/2 N2 (g) + 3/2 H2 (g) AnH° = + 46,19 kJ . mol (3) N204 (g) → 2 NO2 (g), Ar3H = + 58,04 kJ : mol (4) 2 NH3 (g) → N2H (1) + H2 (g) Ar4H° = (5) 2 NO2 (g) + 4 H2 (g) → N2 (g) + 4 H2O (g) ArsH° = – 1 033,66 kJ. mol 142,80 kJ .mol- %3D