1. Ch 2 Matter and Energy
When ice melts- what happens to its chemical composition??
Name a source of energy for your body.
Name some temperature scales.
What is a chemical property? Physical property?

2. Energy The ability to do work
Always involved with change in matter
Physical change-
change in matter from one form to another without change in chemical properties

3. All physical and chemical changes involve change in energy
Change that occurs when one or more substances change into entirely new substances with different properties
All physical and chemical changes involve change in energy
Ex. - water
Ice (melts) water (evaporates) steam
energy energy

4. Endothermic Any change in matter in which energy is absorbed
Exothermic
Any change in matter in which energy is released

5. Law of Conservation of Energy-
Energy cannot be created or destroyed
During any physical or chemical change the total quantity of energy remains constant.
Energy is transferred between system and surroundings

6. Forms of Energy-
Chemical, mechanical, light, heat, electrical, & sound
Heat- transfer of energy between objects that are at different temperatures
Energy can be released or absorbed as heat

7. Temperature- Indicated how hot or cold something is
Measurement of kinetic (motion) energy
Temp. scale –
Celsius- based on freezing point and boiling point of water
Kelvin- absolute zero (all particles have minimum kinetic energy)
Conversion °C = K

8. Transfer of heat may not affect temperature
Transfer of heat may not affect temperature During changes of state – temperatures remain constant
                                                                                                                                    
Heat of vaporization
Heat of fusion

9. Scientific Method –
A series of steps followed to solve problems, including collecting data, formulating a hypothesis, and stating conclusions

11. Hypothesis-
theory or explanation that is based on observations and that can be tested.
Variable-
A factor that could affect the results of an experiment
Controlled experiment-
only one variable

12. Data- recorded observations and or measurements
Theory- an explanation for some phenomenon that is based on observation, experimentation and reasoning
Law- a summary of many experimental results and observations, a law tells how things work
Ex. Law of conservation of mass – products of a reaction must have the same mass as the reactants

13. Models- represent an object, a system, a process, or an idea
Simpler than actual thing
Useful to understand what happens at microscopic and submicroscopic level
                                                                              

14. Measurements and calculations-
Accuracy- description of how close a measurement is to the true value of the quantity measured
Precision- the exactness of a measurement

15. Significant figures-
A prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement
Rules p 57 in text

16. Sig figs con’t
There are 3 digits in this measurement- two you are sure of (16) and one estimate (.1) these are the three significant figures Significant figures are all the digits we are sure of plus one that is estimated.

19. Specific Heat-
Quantity of energy that must be transferred as heat to raise the temp of 1 gram of a substance by 1 K
Table p 60 in text
calculation p 61
follow process!!!!

20. Calculating Specific heat- A 4
Calculating Specific heat A 4.0 g sample of glass was heated from 274 K to 314 K and was found to absorb 32 J of energy as heat. Calculate the specific heat of glass. 1 2 3 4
Gather information
Plan your work
Calculate
Verify your results
Mass = 4.0 g Energy (q) = 32 J initial temp = 274 K final temp = 314 K
T = final temp – initial temp
Cp = m x T q
Cp = g x (40 K)
32 J
Check Units & sig figs
= J/g -K

21. Scientific Notation-All numbers in scientific notation have 2 parts – first part is between 1-10 but has any number of digits as decimals- second part is a power of ten expressed as an exponent
                               
This is a number written as Scientific Notation. The Standard Form is