Heat Of Vaporization Lab

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In this lab, we found the Heat of Vaporization of liquid nitrogen, supported by the data we obtained. First, we calculated the amount of heat absorbed by the 60.00 g of liquid nitrogen we received. To do so, we had to add the liquid nitrogen to a Styrofoam cup containing hot water at 54.3 °C. We took the temperature of the water and nitrogen until it got to its lowest point, 20.2 °C. The water decreased by 31.5 °C after the liquid nitrogen vaporized. The mass decreased as well. After, we found the amount of heat the cup and water released to be 11,400 J, and the measured heat of vaporization to be 191 J/g or 45.6 cals./g. After, we compared this new heat of vaporization with the theoretical value of 199.9 J/g and attained a low negative percent error of -4.5%. In conclusion, this lab experiment was a success. We …show more content…

This warm air entering the cup would increase the temperature of the nitrogen. Temperature is the same as the average kinetic energy, therefore when the average kinetic energy of the nitrogen in this lab came in contact with the air, its molecules began to speed up, increasing the rate of vaporization. This means that some amount of liquid nitrogen vaporized, leaving less in the cup with the water. This would in turn, make the water not reach the lowest temperature that it should have reached because the water and the cup didn’t have as much nitrogen energy to consume. This would make the joules of heat released less, as well as the heat of vaporization values I obtained lower than the theoretical ones. Since the measured heat of vaporization was less than the accepted one, it caused my percent error to be negative. My second unique error has to do with the vaporization of the liquid nitrogen. Once the nitrogen leaves the storage vacuum tank, it begins to boil or vaporize. To accurately calculate the results for this lab, all of the liquid nitrogen we assume, stayed within the cup to cool the

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