What is the work done by a system when it absorbs 47 J of heat and gains 12 J of energy? How much heat is released by a system when 45 J of work is done on it to decrease its energy to 23 J? For a constant-pressure expansion of a gas, the work done by the system (-w) is equal to the pressure P multiplied by the change in volume (ΔV) of a gas. Calculate the work done by the gas when its volume expands from 3.0 L to 8.0 L under atmospheric pressure. How much heat did it absorb if its energy did not change? Note: 1L atm = 101.325 J

Another reaction that is used to propel rockets is N2O4(l)+2N2H4(l)3N2(g)+4H2O(g) This reaction has the advantage that neither product is toxic, so no dangerous pollution is released. When the reaction consumes 10.0 g liquid N2O4, it releases 124 kJ of heat. (a) Is the sign of the enthalpy change positive or negative? (b) What is the value of H for the chemical equation if it is understood to be written in molar quantities?

9.41 Under what conditions does the enthalpy change equal the heat of a process?

White phosphorus, P4, ignites in air to produce P4O10. When 3.56 g P4 is burned, 85.8 kJ of thermal energy is evolved at constant pressure. Calculate the combustion enthalpy of P4.

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.

Given the following thermochemical equations: 4B(s)+3O2(g)2B2O3(s)H=2543.8kJ H2(g)+12 O2(g)H2O(g)H=241.8kJ B2H6(s)+3O2B2O3(s)+3H2O(g)H=2032.9kJ Calculate H for the decomposition of B2H6 into its elements.

Explain the difference between heat capacity and specific heat of a substance.

The head of a strike anywhere match contains tetraphosphorus trisulfide, P4S3. In an experiment, a student burned this compound in an excess of oxygen and found that it evolved 3651 kJ of heat per mole of P4S3 at a constant pressure of 1 atm. She wrote the following thermochemical equation: P4S3(s)+8O2(g)P4O10(s)+3SO2(g);H=3651kJ Calculate the standard enthalpy of formation of P4S3, using this students result and the following standard enthalpies of formation: P4O10(s), 3009.9 kJ/mol; SO2(g), 296.8 kJ/mol. How does this value compare with the value given in Appendix C?

The thermochemical equation for the burning of methane, the main component of natural gas, is CH4(g)+2O2(g)CO2(g)+2H2O(l)H=890kJ (a) Is this reaction endothermic or exothermic? (b) What quantities of reactants and products are assumed if H = 890 kJ? (c) What is the enthalpy change when 1.00 g methane burns in an excess of oxygen?

A 10.00-g sample of acetic acid, HC2H3O2, was burned in a bomb calorimeter in an excess of oxygen. HC2H3O2(l)+2O2(g)2CO2(g)+2H2O(l) The temperature of the calorimeter rose from 25.00C to 35.84C. If the heat capacity of the calorimeter and its contents is 13.43 kJ/C, what is the enthalpy change for the reaction?