LEY DE CHARLES V - T

Observa la tabla y responde ¿Qué ocurre con el volumen al aumentar la temperatura? AUMENTA

¿Qué ocurre con el volumen al disminuir la temperatura? November 2004 ¿Qué ocurre con el volumen al disminuir la temperatura?

LEY DE CHARLES ¿Qué ocurre con el volumen que ocupa el gas al aumentar la temperatura, si la presión se mantiene constante? AUMENTA

¿Qué imagen representa lo que ocurre con el gas cuando se aumenta la temperatura? (Suponga n y P constante)

RESPUESTA: D

Ley de Charles A medida que aumenta la temperatura, el volumen aumenta. Por el contrario, cuando la temperatura disminuye, disminuye el volumen.

Volumen vs. Temperatura en kelvin de un Gas a Presión constante Trial Temperature (T) Volume (V) oC K mL 10.0 283 100 50.0 323 114 100.0 373 132 200.0 473 167 180 160 140 120 100 80 60 40 20 180 160 140 120 100 80 60 40 20 Volume (mL) Trial Ratio: V / T 0.35 mL / K The pressure for this data was NOT at 1 atm. Practice with this data: (where Pressure = 1 atmosphere) Volume Temp (oC) (K) V/T 63.4 L 500 773 0.0821 55.2 400 673 0.0821 47.0 300 573 0.0821 38.8 200 473 0.0821 Hot air rises and gases expand when heated. Charles carried out experiments to quantify the relationship between the temperature and volume of a gas and showed that a plot of the volume of a given sample of gas versus temperature (in ºC) at constant pressure is a straight line. Gay-Lussac showed that a plot of V versus T was a straight line that could be extrapolated to –273.15ºC at zero volume, a theoretical state. The slope of the plot of V versus T varies for the same gas at different pressures, but the intercept remains constant at –273.15ºC. Plots of V versus T for different amounts of varied gases are straight lines with different slopes but the same intercept on the T axis. Significance of the invariant T intercept in plots of V versus T was recognized by Thomson (Lord Kelvin), who postulated that –273.15ºC was the lowest possible temperature that could theoretically be achieved, and he called it absolute zero (0 K). Charles’s and Gay-Lussac’s findings can be stated as: At constant pressure, the volume of a fixed amount of a gas is directly proportional to its absolute temperature (in K). This relationship is referred to as Charles’s law and is stated mathematically as V = (constant) [T (in K)] or V  T (in K, at constant P). origin (0,0 point) 0 100 200 300 400 500 Temperature (K) -273 -200 100 0 100 200 Temperature (oC)

Ley de Charles y su relación con la Temperatura

V vs. T (Kelvin) He 6 5 CH4 4 H2O V (L) 3 H2 2 N2O 1 73 173 273 373 473 573 T (K)

V1 V2 = T1 T2 Ley Matemática de Charles: ¿ Y si cambian las condiciones? V/T = k V1 V2 T1 T2 =

Ejemplo 1: Un gas gas tiene un volumen de 3. 0 L a 127°C Ejemplo 1: Un gas gas tiene un volumen de 3.0 L a 127°C. ¿ Qué volumen ocupará a 227 °C?

Escribir las variables: T1 = 127°C + 273 = 400K V1 = 3.0 L T2 = 227°C + 273 = 5ooK V2 = ? Determine la ley T y V = Ley de Charles

4) Conecte las variables: 3.0L V2 400K 500K = 5) Multiplique cruzado (500K)(3.0L) = V2 (400K) V2 = 3.8L