1. Calculations in Chemistry Scientific Math Continued

2. I CAN convert between common and scientific temperature scales.

3. Temperature vs Heat What is TEMPERATURE and how is it different from HEAT? Temperature and Heat are NOT the same thing. How are they different? Remember KINETIC ENERGY? HEAT is a measure of the TOTAL ENERGY possessed by a substance. TEMPERATURE is a measure of the AVERAGE ENERGY possessed by the particle of a substance.

4. Example Two beakers of water are placed on a hot plate and heated until both reach the boiling point of water, 100 °C. What is the TEMPERATURE of each beaker? 100 °C Which beaker of water has MORE ENERGY? The larger one on the right.

5. Temperature Scales Since the invention of the first modern thermometer in 1724, scientists have created a number of temperature scales. A common widely used scale is the FAHRENHEIT scale. Freezing Point (water) 32 o F. Boiling Point (water) 212 o F. 180 degree range between FP and BP. Temperatures can be LESS THAN ZERO.

6. CELSIUS TEMPERATURE SCALE The Celsius Scale is the preferred scale for most scientific work. Part of the SI (Metric) System Freezing Point is 0 o C. Boiling Point is 100 o C. 100 degree range between FP and BP. Temperatures can be LESS THAN ZERO.

7. For most science work the Celsius Scale is fine. However, in some calculation, temperatures less than ZERO present a problem. – Example Volume/Mass calculations cannot use temperatures less than zero because volume or masses CANNOT BE NEGATIVE. In these instances, a third scale is used.

8. The KELVIN SCALE is based on the expansion and contraction of matter. For every degree of change (+ or -) Kelvin, matter expands or contracts by 1 / 273 of its original volume. If matter’s temperature could be lowered to - -273 oC, [ on the Kelvin Scale] matter would have a ZERO VOLUME, which is THEORETICALLY impossible.

9. This temperature is known as ABSOLUTE ZERO. At this temperature matter would possess NO KINETIC ENERGY! Scientist have come within a few millionths of a degree of absolute zero!

10. Temperature Calculations Often in scientific work, it is necessary to convert temperatures from one system to another. This is easily done with the appropriate equation.

11. Fahrenheit to Celsius To convert a temperature given in o F to Celsius, use this equation: o C = 0.56( o F-32)

12. Celsius to Fahrenheit To convert a temperature in o C to Fahrenheit, use this equation: o F = 1.8 ( o C) + 32

13. Converting Celsius to Kelvin K = o C + 273 Converting Kelvin back to Celcius o C = K – 273

14. Practice Problems Complete the practice problems.