Suppose you have a hypothetical reaction of A + B = C + D and this reaction is a

Question

Suppose you have a hypothetical reaction of A + B = C + D and this reaction is a second-order reaction with a reaction rate constant of 0.734 1/(h[M]). What is the instantaneous rate of reaction in molar/h if the concentration of A is 0.105 M, B is 0.300 M, C is 0.100 M and D is 0.350 M? The units are M/h. Answer is 0.03303 Show your work.

Calculate the change in enthalpy (in MJ) resulting from a 25 pound white phosphorus artillery shell reacting with the oxygen in the atmosphere to form P4O10(s) . The enthalpy of formation can be found in the appendix of your text book. The units are megajoules (MJ). Answer is -269. Show your work.

Thank you

Explanation / Answer

a) The relation between conversion X and initial concentation of A (CAO) is given by

ln((M-XA)/M(1-XA)=CAO*(M-1)Kt

M= CBO/CAO = 0.300/0.105 =2.857

CAO = 0.30M

K=0.7341(hM)

A value of t is assumed and XA is calculated

t=15 minutes

ln[(2.857-XA)/(2.857(1-XA)]= 0.105*(2.857-1)*0.734*15/60

Conversion XA= 0.0525

CA= CAO*(1-XA) = .105*(1-0.0525) =0.09948

dcA/dt = 0.105-0.09948)/(15/60) =0.022

CA=CAO*(1-XA)= 0.105*(1-0.3835) =0.064 moles

Rate = (0.105-0.064)/15/60=0.16

b) Moles of phosphorous = 25*0.4535 =11.3375kg/31=0.365 moles

P4(s) + 5O2(g) -> P4O10(g) ?H= -713.2 Kcal/mol =2852.8*103 KJ/Kgmol

Hence Enthalpy of formation= -2967.3*0.365 =-108.335*10^3Kj

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