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Chemistry 112.3 Fall Semester 2011. Ian Burgess Office Number : Thorv. 256 Telephone : 966-4722 Email : ian.burgess@usask.ca. Chapter 1 : Matter, Measurement and Problem Solving. Outline Atoms and Molecules The Scientific Approach The Classification of Matter

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chemistry 112 3 fall semester 2011

Chemistry 112.3Fall Semester 2011

Ian Burgess

Office Number : Thorv. 256

Telephone : 966-4722

Email : ian.burgess@usask.ca

slide2

Chapter 1 : Matter, Measurement and Problem Solving

  • Outline
  • Atoms and Molecules
  • The Scientific Approach
  • The Classification of Matter
  • Properties and Changes of Matter
  • Energy
  • Units and the S.I. system
  • Reliability of a measurement
  • Solving Chemical Problems
atoms and molecules
Atoms and Molecules
  • atoms
    • are submicroscopic particles
  • molecules
    • two or more atoms attached together
    • molecules come in different shapes and patterns
  • Chemistry is the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules.

Atoms and Molecules

slide4

The Scientific Approach

  • Hypothesis – a tentative interpretation or explanation for an observation
    • falsifiable – confirmed or refuted by other observations
    • tested by experiments – validated or invalidated
  • when similar observations are consistently made, it can lead to a Scientific Law
    • a statement of a behavior that is always observed
    • summarizes past observations and predicts future ones
  • a hypothesis is a potential explanation for a handful of observations
  • a theory is a general explanation for the manifestation and behavior of all nature
    • models
    • pinnacle of scientific knowledge
    • validated or invalidated by experiment and observation

The Scientific Approach

slide6

The Classification of Matter

solid

liquid

gas

Classifying Matter

slide7

Solids

  • The particles in a solid are packed close together and are fixed in position

Classifying Matter

slide8

Gases

  • in the gas state, the particles have complete freedom from each other.

Liquids

  • can take the shape of their container and can flow – however, they don’t have enough freedom to escape and expand to fill the container.
  • in the gas state, there is a lot of empty space between the particles

Classifying Matter

slide9

matter whose composition does not change from one sample to another is called a pure substance.

  • matter whose composition may vary from one sample to another is called a mixture.

Classifying Matter

slide10

Properties and Changes of Matter

  • Composition – refers to the parts or components of a sample of matter and their relative proportions.
  • Physical property - acharacteristics a substance displays without changing its composition.
  • Chemical property - is a characteristic a substance displays only when changing its composition.
  • Physical change –the physical properties of a sample change but its composition remains unchanged.
  • Chemical change –matter is converted to a new kind, with a different composition.

More about matter

slide12

An Example of a Physical Change…

  • changes that alter the state or appearance of the matter without altering the composition are called physical changes

More about matter

slide13

An Example of a Chemical Change…

  • changes that alter the composition of the matter are called chemical changes

More about matter

slide14

Energy

  • changes in matter, both physical and chemical, result in the matter either gaining or releasing energy
  • kinetic energy is energy of motion.
  • potential energy is energy that is stored in matter.
  • you can interconvert kinetic energy and potential energy
  • Law of Conservation of Energy whatever process you do that converts energy from one type or form to another, the total amount of energy remains the same

Energy

units of measurement
Units of Measurement

SI : Système Internationale

Units

derived units
Derived Units

Definition :Combinations of the base quantities of length, mass, time, temperature, etc…

Examples :

Units

slide18

The Reliability of a Measurement

What is the volume in this graduate cylinder ?

All measurements are susceptible to error.

Reliability of a measurement

slide19

Error

Accuracy - How close your experimental measurement is to the correct answer.

Precision - Refers to the degree of reproducibility of a measured quantity.

Reliability of a measurement

slide20

Example

Four groups (each group has 5 students) of Chem 112 students are asked to measure a desk with meter sticks. However, one meter stick is incorrectly labelled. The correct length of the desk is 180 cm. Below are the four sets of data

Group A

168 cm

170 cm

169 cm

167 cm

168 cm

Group B

182 cm

175 cm

177 cm

183 cm

185 cm

Group C

180 cm

179 cm

179 cm

180 cm

181 cm

Group D

168 cm

173 cm

170 cm

165 cm

174 cm

Reliability of a measurement

slide21

Significant Figures

Reliability of a measurement

slide22

Significant Figures

How many significant figures are in each of the following?

0.04450 m

5.0003 km

1.000 × 105 s

0.00002 mm

Reliability of a measurement

slide23

Carrying Significant Figures in Calculations

  • when multiplying or dividing measurements with significant figures, the result has the same number of significant figures as the measurement with the fewest number of significant figures

5.02 × 89,665 × 0.10 = 45.0118 = 45

5.892 ÷ 6.10 = 0.96590 = 0.966

Reliability of a measurement

slide24

when adding or subtracting measurements with significant figures, the result has the same number of decimal places as the measurement with the fewest number of decimal places

5.74 + 0.823 + 2.651 = 9.214 = 9.21

4.8 - 3.965 = 0.835 = 0.8

Reliability of a measurement