This is question no. 6 with sub questions a,b in this picture. and c,d,e in anot

Question

This is question no. 6 with sub questions a,b in this picture. and c,d,e in another picture

a) A mildly restored 'Knight-Rider' 1989 Pontiac Trans Am GTA powered by a 5.7 litre V8 can do a quarter mile S from rest in a timet of about 15 seconds. Using distance: S-a 2, force: F-ma and work: W-FS, calculate the amount of work (energy) in kJ required to do the standing quarter mile given that the mass (m) of this Trans Am is 3,500 pounds. Assume that the acceleration (a) is constant. (This is not actually a good assumption.) You will need to convert lots of units here. Answer. b) The molecule: iso-octane CsHis is actually a pretty good representative molecule in petrol. When liquid iso-octane burns in a limited supply of oxygen (as in hard acceleration) it produces carbon monoxide CO and water according to the following unbalanced reaction: C8H18 (I) + O2(g) ? CO (g) + H2O (l) First, balance this equation. Now answer the following: How much heat in kJ is evolved in the burning of one mole of CSHis to CO? The enthalpies of formation are: ??/ (CsH 18 (I))--208.5 kJ mol-1, ??/ (CO (g))--110.6 kJ mol-1. ??/ (H20 (I))--284.9 kJ mol-I (Check the text to see why you don't need the enthalpy of oxygen.) Answer (show how you get this answer): CO can oxidize further to carbon dioxide CO2 according to the following reaction: CO(g) + ½ O2 (g) ? CO2 (g) and the amount of heat evolved for one mole of CO burning to form one mole of CO2 is 284 kJ Combine the above two chemical equations in order to determine the amount of heat evolved when one mole of C8His burns completely to form CO2

Explanation / Answer

Ans 6

Part a

Calculate the value of acceleration a

Distance S = 0.25 miles x 1609.344 m/mile = 402.336 m

Time t = 15 s

Acceleration a = 2S/t2

= 2 x 402.336 m / 15*15 s2

= 3.57632 m/s2

Work W = F x S

= m x a x S

= (3500 lb x 1kg/2.205 lb) x (3.57632 m/s2) x (402.336 m)

= 2283940.133 (kg-m/s2)-m x 1N/(kg-m/s2)

= 2283940.133 N-m x 1J/(N-m)

= 2283940.133 J x 1kJ/1000 J

W = 2283.94 kJ

Part b

Balanced equation

C8H18 + 8.5 O2 = 8 CO + 9 H2O

Enthalpy of formation of O2 = 0

At standard states, Enthalpy of formation of elements is zero.

Heat evolved = sum of Enthalpy of formation of products - sum of Enthalpy of formation of reactants

= 8*Hf(CO) + 9*Hf(H2O) - Hf(C8H18) - Hf(O2)

= 8*(-110.6) + 9*(-284.9) - (-208.5) - 0

= - 3240.4 kJ/mol

Negative sign shows that the heat is evolved.

Heat evolved on burning of 1 mol of C8H18 = 3240.4 kJ

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