HEAT AND CHANGE OF STATE 65 



13. When snow falls the weather usually moderates. Why (58)? 



14. In a "double boiler," the receptacle containing the substance to 

 be heated is placed hi a larger vessel containing water. How does the 

 water in the second vessel prevent the burning of the substance? (How 

 warm can water be made in an open vessel?) 



15. Liquid air in an open vessel cannot be made warmer than 182C. 

 Why? 



16. Why do not all the ice and snow melt as soon as the temperature 

 rises above the freezing point? 



17. Which contains the more heat, 1000 gallons of boiling water or the 

 nearest lake at zero? Explain. 



18. How many calories will be required to raise the temperature of 

 10 grams of water five degrees Centigrade? 



19. Which would require more heat, to melt five grams of ice or to 

 raise five grams of water 50 hi temperature? 



20. If the temperature of 100 grams of boiling water is reduced 

 twenty degrees how many calories are given off? 



21. If 180 calories are taken from a gram of boiling water what will 

 be its temperature? 



22. Which has the greater amount of heat in it, 1000 cubic centimeters 

 of water at 10C. or 1000 cubic centimeters of iron at the same 

 temperature? 



23. Why is copper not as good as iron for making flat-irons used in 

 ironing (58)? 



24. Why is an aluminum kettle better than an iron one for heating 

 water? 



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