Question

1. Briana has agreed to bring beets to the physics department's party. Uunfortunately she was engaged in an experiment in the lab and lost track of time. she needs to run home and cook the beets but by the time they cook, the party will almost be over. Briana decides that she needs to use her pressure cooker to decrease her cooking time. explain using the ideal gas law how this pressure cooker will allow her to cook the beets faster than a conventional pot on the stove.

2. Denver, CO is called the Mile High City due to its exactly 5,280 foot elevation. Using the ideal gas law, explain any modifications that would have to be made to cook the beets without using a pressure cooker. Explain what physically changes to necessitate the changes in cooking methods

Answer 1

1. At atmospheric pressure the water boils a 100 °C (212 °F). Once this temperature is reached, water in the dish starts boiling and the excess heat is converts the water into steam. But according to ideal gass law(PV = nRT), as temperature is directly proportional to pressure this means that the boiling point of water inside a pressure cooker is now greater than 100 °C (212 °F). That means we need higher temperature to boil the water inside the pressure cooker. So as the temperature increases, the pressure thus increases that results in a superheated water. For example, the pressure inside the cooker can be 100 times that of atmospheric pressure. As we know we need boiling water(not steam) to cook the beets. Thus high pressure boiling water has more heat which cooks the beet faster

2. As from the previous answer we now now that pressure and temperature are directly proportional, when we go up the altitude we have less atmosphereic pressure and the boiling point of water decreases. We also know that adding salt or any solute in water increases the boiling point of water. So without pressure cooker we can add more salt to cook the beets faster