Chem 1A General Chemistry. Chapter 1 Keys to the Study of Chemistry

Transcription

1 1 / 1 Chem 1A General Chemistry Chapter 1 Keys to the Study of Chemistry Dr. Orlando E. Raola FALL 2012

2 Overview 2 / 1

3 3 / 1 Chemistry Chemistry is the study of matter, its properties, the changes that matter undergoes, and the energy associated with these changes.

4 4 / 1 Matter and Energy Matter anything that has both mass and volume the stuff of the universe: books, planets, trees, professors, students. Composition the types and amounts of simpler substances that make up a sample of matter Properties the characteristics that give each substance a unique identity

5 5 / 1 Matter and Energy Matter anything that has both mass and volume the stuff of the universe: books, planets, trees, professors, students. Composition the types and amounts of simpler substances that make up a sample of matter Properties the characteristics that give each substance a unique identity

6 6 / 1 Matter and Energy Matter anything that has both mass and volume the stuff of the universe: books, planets, trees, professors, students. Composition the types and amounts of simpler substances that make up a sample of matter Properties the characteristics that give each substance a unique identity

7 7 / 1 Physical and Chemical Properties Physical Properties properties a substance shows by itself without interacting with another substance - color, melting point, boiling point, density

8 8 / 1 Physical and Chemical Properties Physical Properties Chemical Properties properties a substance shows by itself without interacting with another substance - color, melting point, boiling point, density properties a substance shows as it interacts with, or transforms into, other substances - flammability, corrosiveness

9 The distinction between physical and chemical change 9 / 1

10 10 / 1 Problem We can use visualizations to help us understand the nature of the changes in matter. Is the change depicted chemical or physical?

11 11 / 1 The States of Matter A solid has a fixed shape and volume. Solids may be hard or soft, rigid or flexible. A liquid has a varying shape that conforms to the shape of the container, but a fixed volume. A liquid has an upper surface. A gas has no fixed shape or volume and therefore does not have a surface.

12 The Pysical States of Matter 12 / 1

13 13 / 1 Temperature and Change of State A change of state is a physical change. - Physical form changes, composition does not. Changes in physical state are reversible - by changing the temperature. A chemical change cannot simply be reversed by a change in temperature.

14 14 / 1 Temperature and Change of State A change of state is a physical change. - Physical form changes, composition does not. Changes in physical state are reversible - by changing the temperature. A chemical change cannot simply be reversed by a change in temperature.

15 15 / 1 Temperature and Change of State A change of state is a physical change. - Physical form changes, composition does not. Changes in physical state are reversible - by changing the temperature. A chemical change cannot simply be reversed by a change in temperature.

16 16 / 1 Energy in Chemistry Energy is the ability to do work. Potential Energy is energy due to the position of an object. Kinetic Energy is energy due to the movement of an object. Total Energy = Potential Energy + Kinetic Energy E tot = E kinetic + E potential

17 17 / 1 Energy in Chemistry Energy is the ability to do work. Potential Energy is energy due to the position of an object. Kinetic Energy is energy due to the movement of an object. Total Energy = Potential Energy + Kinetic Energy E tot = E kinetic + E potential

18 18 / 1 Energy in Chemistry Energy is the ability to do work. Potential Energy is energy due to the position of an object. Kinetic Energy is energy due to the movement of an object. Total Energy = Potential Energy + Kinetic Energy E tot = E kinetic + E potential

19 19 / 1 Energy in Chemistry Energy is the ability to do work. Potential Energy is energy due to the position of an object. Kinetic Energy is energy due to the movement of an object. Total Energy = Potential Energy + Kinetic Energy E tot = E kinetic + E potential

20 The scientific approach to understanding nature 20 / 1

21 21 / 1 Units and Conversion Factors The results of measurements are always expressed as the product of a pure number and a unit of measure. length = 4.5 m Conversion Factors allow us to express a quantity with different units. body mass = lb 1 kg lb

22 22 / 1 Units and Conversion Factors The results of measurements are always expressed as the product of a pure number and a unit of measure. length = 4.5 m Conversion Factors allow us to express a quantity with different units. body mass = lb 1 kg lb = kg

23 23 / 1 The SI is the System Used in Scientific Work Fundamental SI Units Fundamental Quantity Unit Symbol length meter m mass kilogram kg time second s thermodynamic temperature kelvin K amount of substance mole mol electric current ampere A luminous intensity candela cd All other units are derived from the fundamental units: Area m 2 Volume m 3 Density kg m 3 Velocity m s 1

24 Unit Conversions 24 / 1