# Experiments and Error Analysis: Ideal Gas Law and the Molar Enthalpy of Vaporization

By bworb
Dec 03, 2013
467 Words

Discussion Section

In the experiment the main concepts were the ideal gas law, the molar enthalpy of vaporization (, and the.

Using the equation and the plotted graph we know that the slope is equal to , with the intercept C. With the plotted points of lnP and 1/T we can find the value. We also know that is independent of temperature as long as the temperature range is limited and the pressure is about 1 atm, which in our situation both are true.

A simple but key procedure that was made in the experiment was when the 10 ml beaker was inverted and put into the 1000ml beaker. This is important because this is when the air bubble was made sure to have the same pressure as the room and satisfy the equation.

When the 1000ml beaker containing the inverted 10 ml graduated cylinder with the air bubble was heated to about 80 degrees Celsius, the air bubble expanded due to the additional water vapor and the expansion of gas at higher temperatures.

Cooling the water in the 1000 ml beaker to about 5 degrees Celsius made it possible to find the number of moles of present air because the water vapor is negligible at this low of a temperature. Once the temperature of the water inside the 10 ml graduated cylinder has equilibrated with the water inside the 1000 ml beaker, the temperature and volume of the air bubble, along with the pressure in the air bubble which is equal to the pressure in the room of the can be used with the ideal gas law to find .

Error Analysis

The standard deviation of the slope of the best fit line was 116.83 of the -4747.76 slope value. The standard deviation of the y-intercept was 0.3458 of the 12.716 y-intercept value. The standard deviation the ΔHvap(water) was 0.9714 of the 39.475 ΔHvap(water) value. The percent deviation of the ΔHvap(water) from the reported literature value of 40.66kJ/mol was 4.0826%.

The 10ml graduated cylinder used had an uncertainty of +/-0.1ml. In the original measurement of water in the graduated cylinder of 8.75ml there would be a 1.14% uncertainty. The yellow digital thermometer had an uncertainty of +/-0.1 degrees Celsius. The thermometer is taking temperatures from 79.5 degrees Celsius to 3.1 degrees Celsius so the percent uncertainty would be anywhere from 0.126% to 3.23%.

In this experiment there were minimal experimental errors and uncertainties. Small errors and uncertainties like the 10 ml graduated cylinder not being flat on the bottom of the 1000ml beaker, leads to a slight misread of the volume but this is such a minimal error that the results would not be too skewed because of it.

The largest sources of error come from the standard deviation for the slope, y-intercept, and ΔHvap(water). Also from the equipment uncertainty of the 10ml graduated cylinder and the yellow digital thermometer. I hate chemistry.

In the experiment the main concepts were the ideal gas law, the molar enthalpy of vaporization (, and the.

Using the equation and the plotted graph we know that the slope is equal to , with the intercept C. With the plotted points of lnP and 1/T we can find the value. We also know that is independent of temperature as long as the temperature range is limited and the pressure is about 1 atm, which in our situation both are true.

A simple but key procedure that was made in the experiment was when the 10 ml beaker was inverted and put into the 1000ml beaker. This is important because this is when the air bubble was made sure to have the same pressure as the room and satisfy the equation.

When the 1000ml beaker containing the inverted 10 ml graduated cylinder with the air bubble was heated to about 80 degrees Celsius, the air bubble expanded due to the additional water vapor and the expansion of gas at higher temperatures.

Cooling the water in the 1000 ml beaker to about 5 degrees Celsius made it possible to find the number of moles of present air because the water vapor is negligible at this low of a temperature. Once the temperature of the water inside the 10 ml graduated cylinder has equilibrated with the water inside the 1000 ml beaker, the temperature and volume of the air bubble, along with the pressure in the air bubble which is equal to the pressure in the room of the can be used with the ideal gas law to find .

Error Analysis

The standard deviation of the slope of the best fit line was 116.83 of the -4747.76 slope value. The standard deviation of the y-intercept was 0.3458 of the 12.716 y-intercept value. The standard deviation the ΔHvap(water) was 0.9714 of the 39.475 ΔHvap(water) value. The percent deviation of the ΔHvap(water) from the reported literature value of 40.66kJ/mol was 4.0826%.

The 10ml graduated cylinder used had an uncertainty of +/-0.1ml. In the original measurement of water in the graduated cylinder of 8.75ml there would be a 1.14% uncertainty. The yellow digital thermometer had an uncertainty of +/-0.1 degrees Celsius. The thermometer is taking temperatures from 79.5 degrees Celsius to 3.1 degrees Celsius so the percent uncertainty would be anywhere from 0.126% to 3.23%.

In this experiment there were minimal experimental errors and uncertainties. Small errors and uncertainties like the 10 ml graduated cylinder not being flat on the bottom of the 1000ml beaker, leads to a slight misread of the volume but this is such a minimal error that the results would not be too skewed because of it.

The largest sources of error come from the standard deviation for the slope, y-intercept, and ΔHvap(water). Also from the equipment uncertainty of the 10ml graduated cylinder and the yellow digital thermometer. I hate chemistry.