A faulty thermometer reads -0.5^(@)C in boiling water at the pressure of 747 mm of Hg. What is the correct temperature when the faulty thermometer reads 45^(@)C ? Actual boiling point of water is 99^(@)C at 734 mm of Hg.

A faulty thermometer reads -0.5^(@)C in boiling water at the pressure

1.	A faulty thermometer reads -0.5^(@)C in boiling water at the pressure of 747 mm of Hg. What is the correct temperature when the faulty thermometer reads 45^(@)C ? Actual boiling point of water is 99^(@)C at 734 mm of Hg.
Answer» Solution :Actual boiling point of water at the PRESSURE of 760 mm of Hg is `100^(@)C`. Now, a decrease in pressure by (760-734) or 26 mm of Hg DECREASES the boiling point of water by (100-99) = `1^(@)C`. `therefore` The decrease in pressure by (760-747) or 13 mm of Hg decreases the boiling point of water by `1/26 times 13 = 0.5^(@)C`. Hence, the boiling point of water at 747 mm of Hg should be (100-0.5) = `99.5^(@)C.` Let the correct TEMPERATURE be `X^(@)C`, when the faulty thermometer reads `45^(@)C`. Hence, `x/(99.5)=(45-(-0.5))/(99-(-0.5))=(45.5)/(99.5) " " therefore x=45.5^(@)C.`