Notes about temperature may be useful for secondary school

1. Temperature is a measure of heat energy.
Temperature is measured in degrees Celsius (Centigrade), Fahrenheit, or Kelvin.
Some high temperatures:
Boiling water at sea level = 100 degrees Celsius;
Molten lava = 2,000 Kelvin;
Tungsten filament of a light bulb = 4,000 Kelvin;

2. The 18th-century French scientist Antoine Lavoisier used two large lenses to ignite a fluid in a container. How did he use the lenses to do this? (See 3. below)

3. In the 18th Century, Antoine Lavoisier used two large convex lenses to focus sunlight (heat energy) onto a container of alcohol and ignite it.

4. The lower the pressure the lower will be the temperature at which water boils. At sea level water boils at 212 degrees Fahrenheit; At 12,087ft in Tibet, water boils at 188.6 degrees Fahrenheit; At the top of Mt. Everest water boils at 159.8 degrees Fahrenheit.

5. The average body temperature of a sparrow is 105.8 degrees Fahrenheit; Butter melts at about 87 degrees Fahrenheit; Arctic seawater freezes at 30 degrees Fahrenheit. (It is salty and so freezes at a lower temperature than pure, freshwater.)

6. Silver melts at 962 degrees Celsius and boils at 2,210 degrees Celsius; Gold melts at 1,064 degrees Celsius and boils at 2,900 degrees Celsius.

7. Temperatures in our universe range from about 3,500,000,000 Kelvin (a supernova) to about 3 Kelvin (space). Our Sun is a class G yellow star and has an average surface temperature of 5,600 Kelvin.

8. The temperature of rock at the bottom of the deepest (12,600ft) mine in South Africa is 328 Kelvin (131 degrees Fahrenheit).

9. All animals need heat to keep their bodies alive but different animals tolerate or need different temperatures. In addition, some animals can maintain constant body temperatures under normal conditions. These animals are called warm-blooded. The body temperature of other types of animals varies with the temperature of their surroundings. These animals are called cold-blooded.

10. The average body temperatures of some warm-blooded animals:
Humans: 98.6 degrees Fahrenheit
Rabbit: 101.3 degrees Fahrenheit
Polar Bear: 99.1 degrees Fahrenheit
Blue Whale: 95.9 degrees Fahrenheit
Owl: 104.4 degrees Fahrenheit
Ostrich: 102.6 degrees Fahrenheit.

11. Some warm-blooded animals hibernate during cold weather and their body temperature falls to conserve energy. The normal temperature of a hibernating dormouse falls from 98.6 degrees Fahrenheit to 64 degrees; The normal temperature of an opossum falls from 95 degrees Fahrenheit to 50.9 degrees.

12. Cold-blooded animals lack internal temperature controls so they bask in the sun to keep warm and then hide in the shade to keep cool. They are most active when when their body teperatures are greater than 90 degrees Fahrenheit. The salamander is cold-blooded and can survive in temperatures of 42.4 through 79.7 degrees Fahrenheit.

13. Here are Celsius (Centigrade) and Fahrenheit comparisons:

Fahrenheit minus 40 0 degrees 32 degrees 50 degrees 95 degrees 140 degrees

Centigrade minus 40 minus 17.78 degrees 0 degrees 10 degrees 35 degrees 60 degrees

What is the temperature of freezing water on the Centigrade scale?

14. Absolute zero is a theoretical temperature. It is that temperature at which all substances have no heat energy. It is defined as zero Kelvin (0 Kelvin). 0 Kelvin is equivalent to -273.16 degrees Celsius, and -459.69 degrees Fahrenheit .

15. The temperature of a substance is a result of the speed at which its molecules are moving. The faster the molecules are moving, the higher the temperature of the substance.

16. Does hot water freeze faster than cold water? No, it does not. However, boiled water has less dissolved air and fewer air bubbles; for this reason water that has been boiled might freeze faster and will form ice that is more dense.

17. Combustion is a chemical reaction in which a substance reacts rapidly with oxygen releasing both heat and light energy.

18. In the 18th Century the German scientist George Stahl (1660-1734) developed the theory that combustion and rusting both involved a substance that he called phlogiston. He theorized that combustible substances contain phlogiston which is used up when they burn. (This theory intrigued scientists of the but was incorrect.)

19. The French scientist Antoine Lavoisier (1743-1794) showed that oxygen is the substance necessary for combustion. Lavoisier showed that the gain in weight when a substance was burned to ash was equivalent to the loss in weight of the air in his experiment. (The air had lost oxygen.)

20. The Celsius (originally called Centigrade) scale is a temperature scale in which 0 (zero) degrees is set at the freezing point of water, and 100 degrees is set at the boiling point of water at sea level. This scale is named after the Swedish scientist Anders Celsius (1701-1744)

21. The Swedish scientist Anders Celsius (1701-1744), who invented the Celsius temperature scale in 1742, actually set the scale with 0 as the boiling point of water and 100 as the freezing point. The scale was reversed soon after its invention.

22. The Fahrenheit temperature scale was devised in 1714 by the German scientist G.D. Fahrenheit. His scale has 180 degrees between the freezing point of water which he set at 32 degrees, and the boiling point of water which he set at 212 degrees. The Fahrenheit scale is still in general use but is not commonly in scientific use where Celsius and Kelvin are the preferred scales.

23. To convert Fahrenheit temperatures to degrees Celsius you can use the following calculation: 1. Subtract 32 from the Fahrenheit temperature; 2. multiply the result by 5; 3. Divide this result by 9. 4. The result is the equivalent in degrees Celsius.

24. The Kelvin temperature scale was devised in 1848 by William Thomson, Lord Kelvin. His scale was not based on any specific substance. Instead, the size of the units (degrees) was set at exactly the same as those of the Celsius scale. However, 0 (zero) on the Kelvin scale is absolute zero, a theoretical temperature at which all substances have no heat energy.

25. In 1967, by international agreement, The Kelvin temperature scale was decided to be a scale of units raher than degrees. It is proper therefore to describe the temperature of the boiling point of water at sea level as being 373.15 Kelvin (not 373,15 degrees Kelvin), and the freezing point of water as 273.15 Kelvin (or 273.15 K)

26. To all countries in the world (except the United States, Burma, South Yemen and Tonga) use the Systeme Internationale d Unites (International System of Units) or SI for short. SI uses the metric system which has all units in multiples of ten. The SI units used for temperature and heat measurement include: Kelvin, therms, and joules.

27. A Calorie (upper-case C) is a kilocalorie and is the unit of heat commonly used to describe the energy content of foods. The calorie and Calorie are being replaced by the joule and kilojoule. Here are some equivalents: 1 Calorie (kilocalorie) = 1,000 calories
1 Calorie = 4,184 joules or 4.184 kilojoules
1 kilojoule = 0.239 kilocalories or Calories.

28. Heat is a form of energy. There are several physical effects of heat including: 1. Changing the temperature of a substance; 2. Changing the state of a substance (as from solid to liquid); 3. Causing expansion of the substance;

29. Heat is transferred from a substance at a higher temperature to one at a lower temperature by conduction, convection, or radiation. Conduction occurs mainly in solids; convection occurs in fluids, and radiation occurs through space, Radiation occurs without the need for any substance to transfer the heat.

30. Water boils at lower temperatures as altitude (height above sea level) increases. This table shows the temperature of boiling water at various altitudes:

Place	Altitude	Water boils
London England Dead Sea Denver Colorado Quito, Ecuador Lhasa, Tibet Mt. Everest (top)	Sea level -1,296 ft 5,280 ft 9,350 ft 12,087 ft 29,002 ft	212.0šF or 100šC 213.8šF or 101šC 203šF or 95šC 194šF or 90šC 188.6šF or 87šC 159.8šF or 71šC

Note: The boiling points of all liquids will be similarly affected. What sorts of things might be affected by the lower boiling points of water and other liquids?