Answer to Question #69464 in Physical Chemistry for Tianna

Question

Given the reaction 4PH3--> P + 6H2 , the half life of the reaction is 35.0s at 680°c. Calculate the time required for 95 of the Phosphine (PH4) to decompose.
2) The acid dissociation constant of a weak acid HA has a value of 1.0×10^-5mol/dm^3. What is the pH of a 0.10mol/dm^3 aqueous solution of HA?
3) Calculate the work done when 50g of iron react with excess HCl in a closed vessel of fixed volume. What is the work done in the reaction at 25°c? (Fe=56g/mol)
4)Given the following bond energies of the following molecules in Kj/mol. Be(Cl2)=243, Be(H2)=436, Be(HCl)=431. Calculate the enthalpy of the reaction 2H2 +2Cl2 --> 4HCl