For the experiment of Investigating Entropy Trail 1: NaOH: 2.037g, H2O: 50.038mL, inital temperature: 21.4°C, and final temperature: 29.2°C Trail 2: NaOH: 2.074g, H2O: 50.017mL, inital temperature: 23.1°C, and final temperature: 30.9°C Trail 3: NaOH: 2.028g, H2O: 50.012mL, inital temperature: 22.9°C, and final temperature: 32.0°C a. Find q system (remember q system =-q sumoundings) b. Find ∆H = Asystem moles salt dissolved

An ideal gas expands isothermally (at constant temperature). The internal energy of an ideal gas remains constant during an isothermal change. If q is 76 J, what are U and w?

Natural gas is mostly CH4. When it burns, the chemical reaction is CH4 g 2O2 g CO2 g 2H2O g The H of combustion of one mole of CH4 at 25.0 C is -890.9 kJ. Calculate q, w, and U under these conditions, assuming an external pressure of 1.07 atm.

The enthalpy of vaporization for water is 40.65 kJ mol-1. As a design engineer for a project in a desert climate, you are exploring the option of using evaporative cooling. (a) If the air has an average volumetric heat capacity of 0.00130 J cm-3 K-1, what is the minimum mass of water that would need to evaporate in order to cool a 5 m? 5 m room with a 3 m ceiling by 5°F using this method? (b) Is this a spontaneous or nonspontaneous process?

A 220-ft3 sample of gas at standard temperature and pressure is compressed into a cylinder, where it exerts pressure of 2000 psi. Calculate the work (in J) performed when this gas expands isothermally against an opposing pressure of 1.0 atm. (The amount of work that can be done is equivalent to the destructive force of about 1/4 lb of dynamite, giving you an idea of how potentially destructive compressed gas cylinders can be if improperly handled!)

What is the sign of the standard Gibbs free-energy change at low temperatures and at high temperatures for the formation of hydrogen sulfide from the elements? H2(g)+18S8(s)H2S(g)

2. Which of the following is true for a spontaneous process but not for a nonspontaneous process? Energy in the universe is concentrated conserved dispersed not conserved

Appendix J lists standard molar entropies S, not standard entropies of formation rS. Why is this possible forentropy but not for internal energy, enthalpy, or Gibbsfree energy?

The standard molar entropy of methanol vapor, CH3OH(g), is 239.8 J K1 mol-1. (a) Calculate the entropy change for the vaporization of 1 mol methanol (use data from Table 16.1 or Appendix J). (b) Calculate the enthalpy of vaporization of methanol, assuming that rS doesnt depend on temperature and taking the boiling point of methanol to be 64.6C.

Explain why the statement No process is 100 efficient is not the best statement of the second law of thermodynamics.