You wish to know the enthalpy change for the formation of liquid PCl3 from the elements. P4 (s) + 6 Cl2 (g) -- --> 4 PC13 (1): Change in enthalpy = #kJ? The enthalpy change for the formation of PCI 5 from the elements can be determined experimentally, as can the enthalpy change for the reaction of PCI 3 (/) with more chlorine to give PCl5 (s): P4 (s) + 10 Cl2 (g) - --> 4 PCl5 (s) H = -1774.0 kJ/mol*rxn PC13() + Cl2 (g) --> PCl5 (s) H = -123.8 kJ/mol*rxn Use these data to estimate the change in enthalpy for the first reaction, the formation for PC|3 from its elements. {answer looks like # kJ}

Write reactions for which the enthalpy change will be a. Hf for solid aluminum oxide. b. the standard enthalpy of combustion of liquid ethanol, C2H5OH(l). c. the standard enthalpy of neutralization of sodium hydroxide solution by hydrochloric acid. d. Hf for gaseous vinyl chloride, C2H3Cl(g). e. the enthalpy of combustion of liquid benzene, C6H6(l). f. the enthalpy of solution of solid ammonium bromide.

A 29.1-mL sample of 1.05 M KOH is mixed with 20.9 mL of 1.07 M HBr in a coffee-cup calorimeter (see Section 6.6 of your text for a description of a coffee-cup calorimeter). The enthalpy of the reaction, written with the lowest whole-number coefficients, is 55.8 kJ. Both solutions are at 21.8C prior to mixing and reacting. What is the final temperature of the reaction mixture? When solving this problem, assume that no heat is lost from the calorimeter to the surroundings, the density of all solutions is 1.00 g/mL, and volumes are additive.

Consider the reaction 2HCl(aq)+Ba(OH)2(aq)BaCl2(aq)+2H2O(l)H=118KJ Calculate the heat when 100.0 rnL of 0.500 M HCl is mixed with 300.0 mL of 0.100 M Ba(OH)2 Assuming that the temperature of both solutions was initially 25.0C and that the final mixture has a mass of 400.0 g and a specific heat capacity of 4.18 J/C g, calculate the final temperature of the mixture.

The enthalpy of combustion of diamond is -395.4 kJ/mol. C s, dia O2 g CO2 g Determine the fH of C s, dia.

The enthalpy change for the following reaction is 393.5 kJ. C(s,graphite)+O2(g)CO2(g) (a) Is energy released from or absorbed by the system in this reaction? (b) What quantities of reactants and products are assumed? (c) Predict the enthalpy change observed when 3.00 g carbon burns in an excess of oxygen.

Give the definition of the standard enthalpy of formation for a substance. Write separate reactions for the formation of NaCl, H2O , C6H12O6, and PbSO4 that have H values equal to Hf for each compound.

An industrial process for manufacturing sulfuric acid, H2SO4, uses hydrogen sulfide, H2S, from the purification of natural gas. In the first step of this process, the hydrogen sulfide is burned to obtain sulfur dioxide, SO2. 2H2S(g)+3O2(g)2H2O(l)+2SO2(g);H=1124kJ The density of sulfur dioxide at 25C and 1.00 atm is 2.62 g/L, and the molar heat capacity is 30.2 J/(mol C). (a) How much heat would be evolved in producing 1.00 L of SO2 at 25C and 1.00 atm? (b) Suppose heat from this reaction is used to heat 1.00 L of the SO2 from 25C to 500C for its use in the next step of the process. What percentage of the heat evolved is required for this?

sample of natural gas is analyzed and found to be88.4% methane (CH4) and 11.6% ethane (C2H6) bymass. The standard enthalpy of combustion of methaneto gaseous carbon dioxide (CO2) and liquid water (H2O) is -891 kJ/mol. Write the equation for the combustionof gaseous ethane to carbon dioxide and water.Calculate the standard enthalpy of combustion of ethaneusing standard enthalpies of formation from Table R-11on page 975. Using that result and the standard enthalpyof combustion of methane in Table 15.3, calculate theenergy released by the combustion of 1 kg of natural gas.

Use data from Table 4.2 to calculate the standard combustion enthalpy for conversion of sulfur dioxide, SO2(g), to sulfur trioxide, SO3(g). Table 4.2 Selected Standard Formation Enthalpies, fH, at 25C