Introduction to Chemistry Chapters 1&3

Pre-class Activity Chemistry is the study of matter and the changes that it undergoes. What is matter? Be prepared to give two examples of matter that can be found in the classroom

Chemistry and Matter Chemistry is the study of matter and the changes that it undergoes. Anything that has mass and takes up space A measurement that reflects the amount of matter

Questions What in the universe isn’t matter? Energy Why aren’t the terms mass and weight interchangeable? Weight is not only a measure of the amount of matter, but also a measure of the effect that gravity has on matter

Scientific Method – A Systematic Approach Draw conclusions and revise hypothesis OBSERVATION HYPOTHESIS EXPERIMENT THEORY SCIENTIFIC LAW Theories are supported by many experiments

Scientific Method Scenario A scientist owns fish that are very sensitive to changes in temperature. One morning, after a huge storm, he came into the lab only to find that all the fish in his tank were dead. He suspected that there might have been a power outage due to the storm, in which the power to the heater may have been interrupted. To test this, he measured the temperature of the tank, only to find that it is normal. Identify the observation, hypothesis and experiment in the paragraph above. Does the result of the experiment support the hypothesis?

Arise following many, many experiments Theory vs. Law Provides an explanation of what occurs in nature Merely states what occurs in nature Arise following many, many experiments

Observations Qualitative vs. Quantitative Hot 300o Temperature Height Mass Length

Experiments A set of controlled observations that test a hypothesis. Key Terms Variable: A quantity or condition that can have more than one value Independent Variable: A variable that is changed by the investigator in an experiment Dependent Variable: A variable the changes in response to the independent variable Control: A standard for comparison

Experimental Design Example The Effect of Temperature on the Respiration Rate of Fish Temp (oC) Respiration Rate What is the dependent variable? What is the independent variable? What would be an appropriate control? What is the relationship between respiration rate and Temperature?

Pure vs. Applied Research Gaining knowledge for the sake of knowledge Vs. Gaining knowledge to solve a specific problem

Benchmark If you haven’t already done so, you should read chapter 1 of your text and complete homework assignments #1-3 listed below. Home work #1 Page 9 #6, 7, and 10 Homework #2 Page 13 #11, 12, 14, and 16 Homework #3 Page 17 #17

Mrs. Pav’s Milk Lab Write-Up Pupose: To determine if milk type affects the migration time of food coloring in the milk experiment Hypothesis: If whole milk is substituted for skim milk in the milk experiment, the food coloring will migrate slower. Materials: In addition to materials listed for the milk lab, whole milk was added Procedure: Refer to written procedure for the milk lab. The migration time of food coloring was measured by using a stop watch to record the time that it took for the food coloring to migrate to the edge of the petri dish. Results: The time for the control (skim milk) was 4.8 seconds. The time for the experimental group (whole milk) was 3.2 seconds. Conclusions: The hypothesis was confirmed by the data because the migration time of food coloring increased for whole milk as compared to skim milk

Pre-class Activity Physical properties of matter are those properties that can be observed or measured without changing the composition of the matter. The ability of a substance to combine with or change into one or more other substances is called a chemical property Does the photograph to the right depict a physical property of water or a chemical property of water? Homework (Due 9/22) Start/Continue Working on chapter(s) review assignment

States of Matter (Physical Forms) Shape Volume Compressibility Solid Liquid Gas Incompressible Definite Definite Nearly Incompressible Indefinite Definite Compressible Indefinite Indefinite

Physical Properties of Matter Physical properties of matter are those properties that can be observed or measured without changing the composition of the matter.

Extensive vs. Intensive Properties Extensive properties are dependent on the amount of matter present Intensive properties are independent of the amount of matter present.

Classification of Matter Contains only one type of matter. AKA pure substances Matter Substances Mixtures Contains more than one type of matter. Physical Change

Physical Change A change which alters a substance without changing its composition

Mixtures Matter Substances Mixtures Physical Change Homogeneous Heterogeneous Constant composition throughout. AKA solutions Not well blended. Individual components remain distinct

Chemical Properties The ability of a substance to combine with or change into one or more substances is called a chemical property A chemical property cannot be observed unless a substance undergoes a chemical change (changes into a new substance)

Substances Matter Substances Mixtures Compounds Elements Physical Change Chemical Change Homogeneous Heterogeneous A pure substance that can not be broken down in to simpler substances by physical or chemical means A chemical combination of two or more different elements

Elements & Compounds A first look at the periodic table… The periodic table is a chart that organizes the elements into a grid of horizontal rows called periods and vertical columns called groups or families.

Evidence of a Chemical Reaction Change in color Change in temperature Endothermic vs. Exothermic Production of a gas Production of a precipitate Absorption of energy Release of energy Two liquids are combined and a solid is formed

Law of Conservation of Mass “Mass is neither created or destroyed in a chemical reaction, it is conserved” Coefficient Subscript 47g + 32g 79g

Benchmark If you haven’t already done so, you should read chapter pages 54-67 of your text and complete homework assignments #4-5 listed below. Home work #4 Page 60 #2, 3, and 5 Homework #5 Page 65 #10, 11, 12, 13, and 15

Separation Techniques Chromatography: Separates the components of mixtures (mobile phase) on the basis of the tendency of each to travel or be drawn across the surface of another material.

Separation Techniques Distillation: Separates homogeneous mixtures based on differences in boiling points.

Separation Techniques Filtration: Uses a porous barrier to separate a solid from a liquid in a heterogeneous mixture.

Separation Techniques Crystallization: A technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance

Pre-Class Question Which of the following photographs represent physical change?

Review What is required to separate a mixture into individual substances? A Physical Change What is the key difference between a physical change and a chemical change? During a physical change the composition of matter stays the same. The composition of a substance is altered as a result of a chemical change. Homework Be prepared for homework quiz #2 on Wednesday 9/21

Compounds Law of Definite Proportions: Elements combine in definite proportions by mass. The percent by mass of each element in a compound will be the same regardless of the quantity of the compound.

Elements & Compounds Law of Definite Proportions… Example

Compounds Law of Multiple Proportions: When different compounds are formed from the same elements, different masses of one element combine with the same relative mass of the other element in small whole numbers. CuCl or CuCl2

Benchmark If you haven’t already done so, you should read pages 68-77 of your text and complete homework assignments #6-7 listed below. Home work #6 Page69 #15, 16, 17, 18, and 19 Homework #3 Page 77 #25, 26, 28, and 30

Review Assignment Page 22 Page 23 Page 82 Page 85 #27, 29, 31, 32, 33, 37, 38, and 39 Page 23 #1, 3, 5, and 7 Page 82 #34, 37, 39, 41, 47, 49, 57, 61, 68, 69, and 71 Page 85 #1, 3, 5, 7, and 9