Calculate ΔE for each of the following. a. q=-47 kJ, w=+88 kJ b. q=+82 kJ, w=+47 kJ

step 1 formula for calculating delta E here is equal to Q plus W. So for A, delta E here is negative 47

Calculate ΔE for each of the following. a. q=-47 kJ,...

Calculate $\Delta E$ for each of the following. $$\begin{array}{l}{\text { a. } q=-47 \mathrm{kJ}, w=+88 \mathrm{kJ}} \\ {\text { b. } q=+82 \mathrm{kJ}, w=+47 \mathrm{kJ}} \\ {\text { c. } q=+47 \mathrm{kJ}, w=0} \\ {\text { d. In which of these cases do the surroundings do }} \\ {\text { work on the system? }}\end{array}$$

Calculate $\Delta E$ for each of the following.
$$\begin{array}{l}{\text { a. } q=-47 \mathrm{kJ}, w=+88 \mathrm{kJ}} \\ {\text { b. } q=+82 \mathrm{kJ}, w=+47 \mathrm{kJ}} \\ {\text { c. } q=+47 \mathrm{kJ}, w=0} \\ {\text { d. In which of these cases do the surroundings do }} \\ {\text { work on the system? }}\end{array}$$

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Key Concepts

Work (w)

Work in thermodynamics is the energy transferred when a force moves the boundary of a system, such as during compression or expansion. It is essential to distinguish between work done on the system (positive) and work done by the system (negative), which directly affects the internal energy change.

First Law of Thermodynamics

This fundamental principle states that the change in a system's internal energy (?E) is equal to the heat added to the system (q) plus the work done on the system (w). It highlights the conservation of energy and provides the basic equation ?E = q + w for analyzing thermodynamic processes.

Heat Transfer (q)

Heat transfer represents the energy exchanged as a result of a temperature difference between the system and its surroundings. The sign of q is positive when heat is absorbed by the system (endothermic process) and negative when heat is released (exothermic process).

Sign Conventions

The proper assignment of positive and negative signs to heat and work is crucial for correctly applying the first law of thermodynamics. Positive work indicates energy being transferred to the system by the surroundings, while negative work indicates the system doing work on the surroundings. This concept helps determine the direction of energy flow in a thermodynamic process.

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