Raoult's law: Difference between revisions
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'''Raoult's law''' states that the [[vapour pressure]] of an [[ideal solution]] of two components is: | '''Raoult's law''' states that the [[vapour pressure]] of an [[ideal solution]] of two components is: | ||
:<math>P_v = X_A P^*_{v,A} + X_B P^*_{v,B}</math> | :<math>P_v = X_A P^*_{v,A} + X_B P^*_{v,B}</math> | ||
where <math>X_i</math> is the [[molar fraction]] of component i, and <math>P^*_{v,i}</math> is the vapour pressure of pure i. | where <math>X_i</math> is the [[molar fraction]] of component <math>i</math>, and <math>P^*_{v,i}</math> is the vapour pressure of pure <math>i</math>. | ||
More generally, Raoult's law describes the [[partial pressure]] of component <math>A</math> in the vapour coexisting with a liquid mixture as: | |||
More generally, | |||
:<math> P_A = X_A P^*_{v,A} </math>. | :<math> P_A = X_A P^*_{v,A} </math>. | ||
This law is obeyed for all components of an ideal solution, and is also obeyed for the solvent of an [[ideal dilute solution]]. The solute's partial pressure of such solutions then obey [[ Henry's law]]. Ideal dilute solutions describe the limiting | This law is obeyed for all components of an ideal solution, and is also obeyed for the solvent of an [[ideal dilute solution]]. The solute's partial pressure of such solutions then obey [[ Henry's law]]. Ideal dilute solutions describe the limiting behaviour of a mixture of infinite dilution. Therefore, all solutions in the limit of infinite dilution obey Raoult's law, i.e.: | ||
:<math> \lim_{X_A \rightarrow 1} P_A = X_A P^*_{v,A} </math>. | :<math> \lim_{X_A \rightarrow 1} P_A = X_A P^*_{v,A} </math>. | ||
==References== | |||
[[category: classical thermodynamics]] | [[category: classical thermodynamics]] | ||
Revision as of 10:12, 19 February 2009
Raoult's law states that the vapour pressure of an ideal solution of two components is:
- Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle P_v = X_A P^*_{v,A} + X_B P^*_{v,B}}
where Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle X_i} is the molar fraction of component Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle i} , and Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle P^*_{v,i}} is the vapour pressure of pure Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle i} . More generally, Raoult's law describes the partial pressure of component Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle A} in the vapour coexisting with a liquid mixture as:
- Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle P_A = X_A P^*_{v,A} } .
This law is obeyed for all components of an ideal solution, and is also obeyed for the solvent of an ideal dilute solution. The solute's partial pressure of such solutions then obey Henry's law. Ideal dilute solutions describe the limiting behaviour of a mixture of infinite dilution. Therefore, all solutions in the limit of infinite dilution obey Raoult's law, i.e.:
- Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \lim_{X_A \rightarrow 1} P_A = X_A P^*_{v,A} } .