Which system does more work: (a) ΔE = –436 J, q = 400 J; or (b) ΔE = 317 J, q = 347 J? In which case is heat added to the system: (a) ΔE = –43 J, w = 40 J; or (b) ΔE = 31 J, w = 34 J?

5.00 × 10−2 mol KOH and an excess of hydrochloric acid are combined in 100.0 mL of water initially at 25.0 °C, leading to a final measured temperature of 31.1 °C. (a) What is the heat flow for the water in the calorimeter, qH2O, in Joules? (b) Assuming the calorimeter constant Ccal = 50.0 J °C , what is the heat flow for the calorimeter, qcal, in Joules? (c) What is the amount of heat given off by the reaction, qrxn, in Joules? (d) What is the molar enthalpy of the neutralization reaction (shown below) as measured in the calorimeter, ∆H◦ rxn in kilojoules per mole? H3O + (aq) + OH– (aq) → 2H2O (l)

Given the standard enthalpy changes for the following two reactions: (1) 4C(s) + 5H₂(g) C4H10(9) (2) C₂H4(g) →→2C(s) + 2H₂(g) (3) 2C₂H4(g) + H₂(g) C4H10 (9) ΔΗ° = -125.6 kJ what is the standard enthalpy change for the reaction: KJ AHO = -52.3 kJ ΔΗ° = ?

If a system has 225 kcal of work done to it, and releases 5.00 x 102 kJ of heat into its surroundings, what is the change in internal energy (AE or AU) of the system? ΔΕ- kJ