Chem lab 2 Heat of Vaporization of Water

heat of vaporization of water

40.79

Guy- Lussac Law

Pair=kTair

T or F: Guy Lussac's law states that at a constant volume, the P of an ideal gas is directly proportional to the T. If a plot for a given set of data for gas is at a constant volume you always get a constant slope

True; V is directly proportional to 1/P and P is directly proportional to T

Percent Error Formula

actual-experimental/actual

ln(P₁/P₂)=-(∆Hvap/R)(1/T₁ - 1/T₂)

for two different vapor pressures and two different temperatures to determine the molar heat of vaporization

Boyle's Law

pressure and volume of a gas have an inverse relationship when the temperature is held constant; constant is k

-∆Hvap/R

slope of line

Determine vapor pressure of water using partial pressure of air

use given data (temp in C then convert to K, and recorded pressure) to find k value using the equation k=Pair/T (T is in Kelvin) k unit will be kPa(or gas unit)∙K⁻¹ Pair=kTair ; plug in k to find Pair ; subtract Pair from Ptotal (given) to find Pwater

Graph for determination of Heat of Vaporization of Water

y axis=lnP x-axis= 1/T (K⁻¹) negative slope

to calculate ∆Hvap of water

∆Hvap=-(slope)(R) R= 8.314 J/mol∙K slope unit is K ∆Hvap unit is kJ