Introduction
Vapor pressure is the pressure of a vapor (gas) at equilibrium; equilibrium occurs when there is no net change between the amount of liquid and the amount of vapor because they balance each other. When the temperature of water becomes extremely low, as it does in this experiment, the rate of vaporization does not matter. The objective of this experiment is to determine the experimental heat of vaporization and compare it to the accepted heat of vaporization of water (40.7 kj/mol). The molar heat of vaporization is the amount of energy required to vaporize one mole of a liquid at one atm and the symbol ∆ Hvap is used. The process by which the molar heat of vaporization is calculated is though the slope of a graph. The volume of …show more content…
The percent error (accepted-experimental/accepted × 100) will determine how close the experimental was to the accepted. The hypothesis for this experiment is that the experimental ∆ Hvap will not be more than 5 kj/mol away from the accepted value. The Clausius-Clepeyron equation describes the relationship between the molar heat of vaporization, the natural logarithm of the vapor pressures, and the temperature. The formula is ln (Pvap) =-∆Hvap/R *(1/Tk) +C. The equation can be modified so it can use two points on the graph and the new equation is ln (Pvap) =-∆Hvap/R × (1/T2-1/T1). The value used for R should be 8.314 × 10-3 …show more content…
This is the only increase in volume observed during the experiment; the remaining volumes gradually decrease as the temperature gets closer to the freezing point of water (0° C or 273 K). Each volume recorded must have 0.2 ml taken off to make up for the volume difference due to the inversion of the graduated cylinder. The barometric pressure was converted from 30.2 in to 1.01 atm; the value is the same for all of the temperatures. Similarly, the value for the moles of air will remain the same for all of the temperatures and the equation n=PV/RT will be used to calculate
Vapor pressure is the pressure of a vapor (gas) at equilibrium; equilibrium occurs when there is no net change between the amount of liquid and the amount of vapor because they balance each other. When the temperature of water becomes extremely low, as it does in this experiment, the rate of vaporization does not matter. The objective of this experiment is to determine the experimental heat of vaporization and compare it to the accepted heat of vaporization of water (40.7 kj/mol). The molar heat of vaporization is the amount of energy required to vaporize one mole of a liquid at one atm and the symbol ∆ Hvap is used. The process by which the molar heat of vaporization is calculated is though the slope of a graph. The volume of …show more content…
The percent error (accepted-experimental/accepted × 100) will determine how close the experimental was to the accepted. The hypothesis for this experiment is that the experimental ∆ Hvap will not be more than 5 kj/mol away from the accepted value. The Clausius-Clepeyron equation describes the relationship between the molar heat of vaporization, the natural logarithm of the vapor pressures, and the temperature. The formula is ln (Pvap) =-∆Hvap/R *(1/Tk) +C. The equation can be modified so it can use two points on the graph and the new equation is ln (Pvap) =-∆Hvap/R × (1/T2-1/T1). The value used for R should be 8.314 × 10-3 …show more content…
This is the only increase in volume observed during the experiment; the remaining volumes gradually decrease as the temperature gets closer to the freezing point of water (0° C or 273 K). Each volume recorded must have 0.2 ml taken off to make up for the volume difference due to the inversion of the graduated cylinder. The barometric pressure was converted from 30.2 in to 1.01 atm; the value is the same for all of the temperatures. Similarly, the value for the moles of air will remain the same for all of the temperatures and the equation n=PV/RT will be used to calculate