Discussion of the section on changes of phase

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Q1: When there is a late cold snap, fruit farmers spray water on their trees to prevent the flower buds from freezing. The water comes out of the farm pond and is not at all warm! How does spraying the cold water on the trees prevent freezing damage?

Q2: You can stick your hand in a 300 F oven and not get burned (if you don't touch anything!), but the steam from a bag of microwave popcorn will burn you. What is the most important difference between these?

The temperature of the water vapor is above 300 F.     
The water vapor in the popcorn bag is under pressure     
Only the oven rack is that hot. The air in the oven is much cooler     
The water vapor will condense to form water on your hand.     

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