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Thermodynamics: Pressure-Volume Work

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Wize University Chemistry Textbook > Thermodynamics: Part 1: (0th law, 1st law, Calorimetry, Enthalpy)

The 1st Law of Thermodynamics and Work

5 Activities

A system composed of 4.50 L of N2 in a cylinder expands against an external pressure of 300 kPa until its volume is 6.30 L.
  1. What is the value of w for this process?
  2. What would the value be if the external pressure was 0 kPa?
More The 1st Law of Thermodynamics and Work Questions:
The enthalpy of combustion for ethanol (C2H5OH) is -1370.7 kJ/mol. Calculate q, w, ΔH and ΔU when 45g of ethanol are burned at 1atm and 298K.
Do not write the units when you input your answer.
Thermodynamics: Internal Energy
The enthalpy of combustion for ethanol (C2H5OH) is -1370.7 kJ/mol. Calculate q, w and ΔU when 45.0g of ethanol are burned at 1atm and 298K.
Answers need to be in scientific notation, with proper significant figures. Give all values in kJ.
A steam turbine uses some form of energy to evaporate water, heat the vapour and move a cylinder. We can think of this a constant pressure process, where H2O(l)→H2O(g)H_2O(l) → H_2O(g).
Complete the following sentences about this process by choosing one description per line. Enter the answers separated by a comma in the box below.
This process is exothermic / endothermic.
Thermodynamics: Pressure-Volume Work
Which of these reactions involve pressure-volume work being done on the system?
Thermodynamics
2.3 moles of an ideal gas initially at -12oC and 16 atm underwent a complete expansion against a constant external pressure of 1atm and did 1.1kJ of work. Calculate ΔE, Δ𝐻, 𝑎𝑛𝑑 𝑞 for this process.
A Piston containing an 1.3 moles of an Ideal Gas undergoes a compression from 32 L to 27 L against a constant external pressure of 178 kPa. During this transformation the temperature does not change. Calculate ΔE,q and w\Delta E, q\ and\ wfor this transformation. Report your answers in Joules with no decimal points. You do not have to include the unit in your answer
If an exothermic process releases 555 J of heat to the surroundings when the volume of the system is kept constant, how would the amount of heat released change if the system were allowed to expand instead?
Thermodynamics: Work
The diagram below has 4 identical gas systems at a constant pressure. Assume that the long arrows are all the exact same length and have the exact same energy. Assume that all the short arrows have the exact same length and exact same energy.
q=heat, w=work. Which of the following statements is true?
The enthalpy of combustion for ethanol (C2H5OH) is -1338.9 kJ. Calculate q, w, ΔH and ΔU when ethanol is burned at 1atm and 298K.
Based on signs of q and w, was heat released or gained, work done on or by system?
Thermodynamics: Work
4 moles of neon was confined to a 8L flask initially at room temperature underwent an isothermal expansion into a vacuum at 348K and constant volume. Calculate ∆𝑈, w, 𝑎𝑛𝑑 𝑞 for this process.
The enthalpy of combustion for ethanol (C2H5OH) is -1370.7 kJ/mol. Calculate q, w, ΔH and ΔU when 45g of ethanol are burned at 1atm and 298K.
The enthalpy of combustion for ethanol C2H5OH is -1370.7 kJ/mol. Calculate q, w, ΔH and ΔU when 45 g of ethanol are burned at 1 atm and 298 K.
q
w
Thermodynamics: Review
Fill in the following blanks!
How to fill in this table:
For the first column we have ∆U. Your options are temperature is constant, temperature increases, or temperature decreases