Problem 31
Write the equation that states the first law of thermodynamics. In your own words, what does this statement mean in terms of energy exchanges between a system and its surroundings?
Problem 32
How are heat and work defined?
Problem 34
Why are heat and work not state functions?
Problem 37
How is enthalpy defined?
Problem 38
What is the sign of \(\Delta H\) for an endothermic change?
Problem 40
If a system containing gases expands and pushes back a piston against a constant opposing pressure, what equation describes the work done on the system?
Problem 42
What distinguishes a thermochemical equation from an ordinary chemical equation?
Problem 43
Why are fractional coefficients permitted in a balanced thermochemical equation? If a formula in a thermochemical equation has a coefficient of \(\frac{1}{2}\), what does it signify?
Problem 44
What fundamental fact about \(\Delta H\) makes Hess's law possible?
Problem 45
What two conditions must be met by a thermochemical equation so that its standard enthalpy change can be given the symbol \(\Delta H_{\mathrm{f}}^{\circ}\) ?
