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

55. Does the standard enthalpy of formation of H2O(g) differ from ΔH° for the reaction 2H2(g)+O2(g)⟶2H2O(g)?

1. Methanol CH3OH is a potential source of fuel. An experiment was conducted to determine the enthalpy of combustion of methanol. 2.00 g of methanol was used to heat 150 g of water. The temperature of the water increased from 25°C to 87 °C. (Given that the specific heat capacity of water is 4.18 J K-1 g-1) Define the term standard enthalpy of combustion with reference to methanol. Use the data above to determine the enthalpy of combustion of methanol (show solutions).   2. Calculate the e.m.f of the following cell in the image (show solutions).

Substance SiO,(s) SICLO H,O) HCIE) AH°, (kJ/mol) -910.7 -687.0 -285.83 -92.307 Calculate the standard enthalpy change for the following reaction: SICI4(1) + 2H20(1) → SIO2 (s) + 4HCI (g)

PCI5(s) can be prepared by the reaction PCI3(1) + Cl2(g) - PCI5(s). Calculate the enthalpy change (in kJ) that accompanies the production of 100.0 g of PCI5(s) by the above reaction, given the following data. P4(s) + 6 Cl2(g) - 4 PC|3(1) AH° = -1280 kJ per mole of P4(s) %3D P4(s) + 10 Cl2(g) – 4 PCI5(s) ΔΗ AH° = -1774 kJ per mole of P4(s) +59.3 -59.3 +124 -124 -258

(b) The standard enthalpy change for the following reaction is -697 kJ at 298 K.2 Zn(s) + O2(g)2 ZnO(s)What is the standard heat of formation of ZnO(s)

1 If the standard enthalpy of cembustion of gaseous cyclopropane, C3H6, is -2091.2 kJ mol- at 25 C, calculate the standard enthalpy of formation of the compound at 298 K. (The standard enthalpy of combustion is the heat of combustion of one mole of a compound to the most stable combustion products, which are CO2(g) and H20(1) in the case of hydrocarbons. The standard enthalpy of formation is the enthalpy of formation of one mole of a compound from its constituent elements, the compound and its constituent elements in their standard states.)

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° = ?

（1）Consider the reaction: 2A (g) + 3 B (g) → 2 C (g)     ΔHrxn = +254.3 kJ What will be the enthalpy change (in kJ) if 0.471 mol B reacts in excess A?   （2）Consider the reaction: C (s) + O2 (g) → CO2 (g)     ΔHrxn = -393.5 kJ What mass of carbon (in g) must be reacted via this mechanism to release 581.2 kJ of heat?