1. Matter and Energy
Chapter 2
Chemistry 1 5.0

2. Energy and Change Energy is the capacity to do work.
All physical and chemical changes require energy.
Endothermic - describes a process in which heat is absorbed from the environment.
Exothermic – describes a process in which heat is released into the environment.

3. Law of Conservation of Energy
Energy is neither created, nor destroyed. It just changes forms.

4. Heat
Heat is the energy transferred between objects that are at different temperatures. This heat is always transferred from the hotter object to the colder object.
Types of Energy
Potential energy – stored energy
Kinetic energy – energy of motion

6. Heat Temperature is not the same as heat.
Temperature is a measure of the average kinetic energy of the particles in an object.
A temperature change is a result of a energy transfer.
Temperature vs. Heat Animation

7. TEMPERATURE SCALES
                                                                                    

8. Celsius and Kelvin Temps.
K = °C + 273
°C = K
Zero Point on Kelvin Scale – Absolute Zero
0 K and -273 °C
All motion of particles stops! No kinetic energy.

9. Heat Transfer Transfer of heat may not affect temperature.
During a phase change, the temperature will remain constant until all of the substance has changed state.
The temperature will increase when a substance is a solid, liquid, or gas.

10. Phase Change Diagram

11. Kinetic Theory of Matter
Gases posses the greatest amount of kinetic energy.
Two factors that determine the state of matter of a substance: speed of particles and distance
There are two factors contribute to the attraction between the particles.

12. Kinetic Theory of Matter
Substances change phases when they overcome these attractions.
The overall kinetic energy will not change until the entire substance has completely changed.
Comparison of the three states of matter

13. Specific Heat
The amount of heat necessary to raise 1g of a substance 1°C. This is the relationship between energy transferred as heat and the substances temperature change.

14. Common Specific Heats

15. The scientific method is a systematic approach to gather knowledge.
Observation
Question
Hypothesis
Experiment
Conclusion
All hypotheses must be able to be tested in order to be a true hypothesis.

16. Experiment Natural Law – Describes how nature behaves
Theory – Explains why nature behaves the way it does
A theory and a hypothesis are both explanations, but a theory is an explanation formed after much experimentation.

17. Variables in a Experiment
Independent Variable - You control
Dependent Variable – Variable factor – what is being tested
Experimental Control – Factor that remains constant for comparison

18. D. Factors in an Experiment
Independent: most regular variable – goes on the X-axis
Dependent: what you are testing – goes on the Y-axis
Experimental Control: part of the experiment that stays
the same.
Dependent variable
“Y” axis
Independent variable
“X” axis

19. Uncertainty in Measurement
Measurements are uncertain because:
1) Instruments are not free from error.
2) Measuring involves some estimation.
Precision –when the instrument gives you about the same results under similar conditions. The smaller the increments of measurement an instrument has, the more precise it can be.
Accuracy – when the experimental value is close to the actual value.

20. What is the goal for a game of darts?
Hitting the Bulls Eye!

21. Label the following data as accurate, precise, neither, or both.
1) 200g, 1g, 40g
Neither
2) 78g, 80g, 79g
Precise
3) 16g, 14g, 17g
Accurate and Precise

22. Significant Figures and Digits
A prescribed decimal that determines the amount of rounding off to be done base on the precision of the experiment.
ALWAYS ESTIMATE 1 DIGIT MORE THAN THE INSTRUMENT MEASURES.
Significant digits include measured digits and the estimated digit.

23. VI. Significant Digits
A. Significant Digits include measured digits and
estimated digits.
Use Atlantic-Pacific Rule – imagine a US map
decimal
point
decimal
point
Pacific
Atlantic
resent
bsent

24. 1100
2 significant digits
4 significant digits
1100.
8 significant digits
2 significant digits
0.025
5 significant digits
1,000,100
5 significant digits
Decimal Absent Start counting with the 1st nonzero digit and count all the rest.
Decimal Present Start counting with the 1st nonzero digit and count all the rest.

25. How to use a graduated cylinder
Read the
meniscus

26. How to use a graduated cylinder
36.4 mL
19.0 mL
6.25 mL

27. How to read a triple beam balanceg
Ohaus Triple Beam Balance Tutorial
Reading A Triple Beam Balance Tutorial

28. How to read a triple beam balanceg
Ohaus Triple Beam Balance Tutorial
Reading A Triple Beam Balance Tutorial

29. Significant Digits in Addition and Subtraction
Add or subtract numbers
Answer can only be as exact as the least exact number. (Look at the decimal place)
Ex cm cm
4.17 cm
4.2 cm

30. Significant Digits and Multiplication and Division
Multiply and Divide the numbers.
Round answer to the same number of significant digits as the number with the fewest significant digits.
Ex cm / cm
13.2

31. Scientific Notation 1) 2700 2.7 x 103 2) 8,000,000 8 x 106 3) 0.0035
1) 2700
2.7 x 103
2) 8,000,000
8 x 106 3)
3.5 x 10-3 4)
1.0 x 10-2

32. 1st Commandment of Chemistry: KNOW THY CALCULATOR!
Find the “EE” key – it may be a 2nd function!
If you have a graphing calculator look for the following keys:
Find the (-) key.

33. Look at the calculator that is similar to yours…
Find the “Exp” or “x10x”
1st Law of Chemistry:
Know Thy Calculator!
Look at the calculator that is similar to yours…
Find the “(-)” or the “+/-” key.

34. Scientific Notation 1) Multiply 3.7 x 102 by 5.1 x 103
Answer: 19 x 105
2) Divide 2.3 x 10-3 by 4.6 x 10-6
Answer: 5.0 x 102

35. Scientific Notation
Add 9.67x x103
Answer: 9.5 x 103