Effect of temperature on gasphase chemical equilibria

Assume that the reaction entropy and enthalpy changes (AS° and AH°) appearing in the last term in Eq (9.21) are independent of temperature. Taking the logarithms of the first and last terms, and differentiating with respect to temperature yields:

This useful relation is known as the Van'tHoffequation. It can be shown to be valid even if AHo and ASo are temperature-dependent (see Problem 9.17). However, the discussions in Sects. 9.2 and 9.3 suggested that these reaction properties vary little with temperature, and in most cases can be treated as constants. According to Eq (9.25), a plot of experimental measurements in the form of lnKP Vs 1/T should be a straight line with a slope equal to -AHo/R.

Equation (9.25) is also the source of the following useful rules shown in Fig. 9.3.

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Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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