Chapter 2

Measurements and Calculations

Paper Cup Demo

• http://www.youtube.com/watch?v=gQpUQu9bkAc&feature=related

I. Scientific Method

* a systematic approach to solving a problem (pp13) 1. State the problem 2. Gather information 3. Form hypothesis 4. Perform experiments 5. Record and analysis data 6. State conclusion

II. Units of Measurements

• Factor/Label: ex’s

• Derived Units– Table 2-3 pp 36

• Density: = (m) / (v) units??g/ml

***table 2-4 pp 38**

• Volume: = (l) (w) (h) units??cm3

A. Heat and Temp

*Temp:

*Heat:

ex’s: pp 511-512

-Kelvin: Freeze: 273.15 Boil: 373.15 K = (C) + 273 0 K is absolute 0

- Celsius Freeze = 0 °C

• Boil = 100 °C

• ° C = (5/9) (F - 32)

- Fahrenheit:• Freeze = 32 °F

• Boil = 212 °F

• °F = (9/5) (°C) + 32

-Units of Heat

*Joule (J)

*Calorie (c): c = 4.184

- Heat Cap. and Spec. Heat

*HC:

pp 513 Fig. 17-1

- Spec. Heat= heat lost or gained (J or Cal)

mass(g) X ∆ in Temp (°C)

Cp = ______q______ (m) (∆ T)

Examples

1. Determine the specific heat of a material if a 35g sample absorbed 48 J as it was heated from 293 K to 313 K.

A: .069 J/(g*K)

Examples

2. How much heat is needed to raise the temperature of 5 g of gold by 25 C?

A: 16 J

Examples

3. If 980 kJ of energy are added to 6.2 L of water at 291 K, what will the final temperature of the water be?

A: 329 K

Elements Introduction

• http://www.youtube.com/watch?v=DYW50F42ss8

• http://www.youtube.com/watch?v=AGZ20OrmYBs

III. Scientific Measurements

*Accuracy:

*Precision:

ex’s: pp 44

*Percent Error = Valueacc - Valueexp

Valueacc

*Significant Figures:ex’s:

*Scientific Notation:1. Move dec. right until only 1 nonzero digit

remains2. Determ Expo by the # of spaces moved--

Left + Right -

IV. Solving Quantitative Problems

1. Write what you know and what you are trying to find

2. Set up F/L parentheses3. Get rid of unit4. Bigger unit = 15. Make a true statement in the

parentheses

6. Calculate

7. See if the answer is logical

8. Write units

-Proportional Relationships1. Directly: y/x = k or y = kx2. Inversely: xy = k or y = k/x

**ex’s and graphshttp://mathcentral.uregina.ca/QQ/

database/QQ.09.00/ellis1.html