Name _____________________________________
Date ___________
Phase Changes and How a Refrigerator Works Webquest
Directions: Use the link indicated to answer the questions below. This counts as a quiz grade.
http://www.howstuffworks.com/refrigerator.htm Go to the website at left then navigate through
the website by using the “next page” button to answer the questions below. The questions are in
order.
1.
Prior to refrigeration, the only method to preserve meat was to _______________
______.
2.
Cold temperatures in the refrigerator keep food fresh longer because they slow down the
activity of ___________________ so it takes longer for foods to ____________________.
3.
How quickly will milk spoil at room temperature?
___________________________
4.
How long will milk last in the refrigerator?
5.
In the freezer, bacteria are __________________________ altogether. (But they are still
alive.)
6.
A refrigerator uses the ___________________________ of a liquid to ______________ heat.
7.
The liquid used to cool the refrigerator is called the _____________________________.
8.
This liquid evaporates at a very ___________ temperature. If you put it on your skin it
____________________________________
would __________________ your skin as it ____________________.
9.
List the 5 important parts of a refrigerator.
_______________________
_______________________
_______________________
_______________________
_______________________
10.
In order for the refrigerator to keep reusing the refrigerant, the liquid must be
_________________ (turned from a liquid to a gas) then ___________________(turned from
a gas to a liquid) over and over again. Which part of the refrigerator squeezes the gas
molecules into a smaller space until they are much closer together?
___________________________________
11.
When the molecules are closer together they will collide more frequently and have a
__________ temperature.
12.
In order for the compressed refrigerant to change from a gas to a liquid it must first lose
______________ to the surroundings. This is done through coils on the outside (usually the
back) of the refrigerator. This is why it usually feels hot behind or under your fridge.
13.
The liquid refrigerant is then pumped through an_______________________ valve where the
liquid is given more room to ________________ and evaporates to a gas.
14.
The process of evaporation absorbs heat so it is considered to be _____________________
(endothermic or exothermic)
15.
This very cold gas now flows through coils inside the refrigerator where it _____________
heat from the food compartment. The cycle then repeats until the fridge is at the required
temperature.
16.
On the diagram below, label the following: inside fridge, compressor, expansion valve, and
circle hot or cold, liquid or gas for each choice given.
Pipes feel hot or cold?
(liquid or gas?)
Pipes feel hot or cold?
(liquid or gas?)
Draw some conclusions about what you have read.
17. Explain why frozen food will eventually spoil when it is allowed to thaw. For instance, a steak
can be frozen in airtight packaging. If it is then left in the packaging at room temperature for
several days it will spoil. Why?
18. Can you air condition your kitchen by leaving the fridge door open? Explain.
Research: Use the other pages on this site to find answers to the following questions.
19. Name at least 6 ways to preserve foods other than refrigeration.
20. Is the butane in a lighter a liquid or a gas? Why won’t a lighter work well on a cold day?
21. Why isn’t ammonia used as the refrigerant in your refrigerator?
22. What is the problem with CFC’s used as the refrigerant?
23. If you place a bowl of water in your oven at 400oF, what is the maximum temperature the
What is the significance of this temperature?
liquid water can be heated to?