Transcript Chapter 1
Chapter 1 Chemistry: The Study of Matter What is Chemistry? The study of matter, its composition, properties, and the changes it undergoes Applied Chemistry is the using of chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing Pure Chemistry gathers knowledge for knowledge sake Which Comes First? Applied Pure comes Chemistry usually first, applied later Called technology Or engineering Can’t be good or bad Chemistry Pure chemistry can explain behavior that has been used without knowing why Steel swords Can be good or bad depending on use Applied Chemistry Material Design Plastics Paints Nanotechnology Scale Macroscopic- Big enough to see Microscopic- Too small to see unaided Nanotechnology- manipulating individual atoms and molecules Applied Chemistry Energy Ability to do work Different types can be converted to each other Conservation More efficient conversion Insulation Production –new sources Storage- batteries, fuel cells Applied Chemistry Agriculture Production- fertilizers, soil tests Protection – pesticide, herbicide Medicine Drugs Materials- hips, artificial skin Biotechnology- using organisms as a means of production Applied Chemistry Environment- Pollution Eliminate sources Treatment once polluted Astronomy Remote analysis of stars from their light Analysis of extraterrestrial samples Branches of Chemistry Analytical Chemistry -studies composition of substances. Organic Chemistry -compounds containing carbon Inorganic Chemistry -substances without carbon Biochemistry- Chemistry of living things Physical Chemistry studies behavior of substances rates and mechanisms of reactions energy transfers Alchemy Forerunner of chemistry Mystical- search for perfection Practical- developed glassware and techniques used today Tried to change elements Faulty assumptions and lack of logic led them astray Chemistry is A natural science A language with its own vocabulary A way of thinking Scientific Method A way of solving problems or answering questions Starts with observation- noting and recording facts Hypothesis- an educated guess as to the cause of the problem or answer to the question Scientific Method Experiment- designed to test the hypothesis Only two possible answers 1) hypothesis is right 2) hypothesis is wrong Generates data observations from experiments Modify hypothesis- repeat the cycle Variables Controlled experiment- Only want one thing to change at a time in a laboratory. Manipulated variable- What you change or control directly Also called independent variable Responding variable – What changes as a result. No direct control Also called dependent variable Observations Hypothesis Theory (Model) Modify Experiment Prediction Law Experiment Observations Hypothesis Experiment Cycle repeats many times. The hypothesis gets more and more certain. Becomes a theory A thoroughly tested model that explains why things behave a certain way. Observations Hypothesis Experiment Theory can never be proven. Useful because they predict behavior Help us form mental pictures of processes (models) Observations Hypothesis Experiment Another outcome is that certain behavior is repeated many times Scientific Law is developed Description of how things behave Law - how Theory- why Observations Hypothesis Theory (Model) Modify Experiment Prediction Law Experiment Law vs. Theory Theory can’t be proved; always the possibility that a new experiment will disprove a theory Law described a natural phenomenon, but does not attempt to explain it Communication Use Journals Do research Write article Describe procedures, methods, and findings Submit for peer review Sent back for editing Publish Letters to editor respond. Frame of Reference What is it? Physics Definition- system of objects that are not moving with respect to one another Dictionary Definition- set of ideas, facts, or circumstances within which something exists. What does Frame of Reference mean to the world of Chemistry? What is Matter? Matter is anything that takes up space and has mass Mass is the amount of matter in an object Mass is resistance to change in motion along a smooth and level surface Types of Matter Substance- a particular kind of matter – pure Mixture- more than one kind of matter Properties Words that describe matter (adjectives) Physical Properties- a quality or condition of a substance that can be observed or measured without changing the substance’s composition Chemical Properties- a property that can be observed by changing the type of substance Examples of Physical Properties 1) 2) 3) 4) 5) 6) 7) 8) 9) Color Solubility Odor Hardness Density Melting Point Boiling Point Size Shape States of Matter Solid- matter that has a definite shape and volume Liquid- matter that flows and has a fixed volume Gas- matter that takes up both the shape and volume of a container Vapor- a substance that is currently a gas but normally is a liquid or solid at room temperature. Plasma- matter consisting of a gaseous mixture of electrons and positive ions. Not Matter Chart Properties: Solid Liquid Mass Definite Definite Gas or Vapor Definite Shape Rigid Indefinite Indefinite Volume Definite Definite Indefinite Temp. Small Moderate Large Increase Expansion Expansion Expansion ComNo No Yes Pressible? States of Matter Definite Definite Temp. ComVolume? Shape? increase pressible? Solid Liquid Gas YES YES NO YES Small Expans. NO NO Small Expans. NO NO Large Expans. YES Condense Freeze Evaporate Melt Solid Liquid Gas Physical Changes Physical Change- alters a substance without changing its composition Key Terms: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Boil Freeze Dissolve Melt Condense Break Split Crack Crush Cutting Mixtures Mixture- Physical blend of two or more substances Mixture has variable composition Two Types of Mixtures Heterogeneous- not uniform in composition Homogeneous- completely uniform in compostion Example Heterogeneous I. Blood II. Chocolate Chip Cookie III. Soil IV. Blood V. Mixed Salad Homogeneous I. Air II. Brass III. Black Coffee IV. Motor Oil V. Water Solutions Homogeneous Mixture Mixed molecule by molecule Example: Sugar in Water (same composition as any other portion) Can occur between any state of matter Common Solutions Gas in Gas- O2 in N (air) Liquid in Gas- Water Vapor Gas in Liquid- CO2 in Water (soda water) Liquid in Liquid- Acetic Acid in Water (vinegar) Solid in Liquid- Kool Aid Solid in Solid- Copper in Silver (sterling silver) Solutions Like all mixtures, they keep the properties of the components Can by separated by physical means Not easily separated- can be separated The Metric System Measuring The numbers are only half of a measurement. It is 10 long. 10 what? Numbers without units are meaningless. How many feet in a yard? A mile? A rod? The Metric System Easier to use because it is a decimal system. Every conversion is by some power of 10. A metric unit has two parts. A prefix and a base unit. prefix tells you how many times to divide or multiply by 10. Base Units Length - meter - more than a yard - m Mass - grams - about a raisin - g Time - second - s Temperature - Kelvin or ºCelsius K or ºC Energy - Joules- J Volume - Liter - half of a two liter bottle- L Amount of substance - mole - mol Prefixes kilo k 1000 times deci d 1/10 centi c 1/100 milli m 1/1000 kilometer - about 0.6 miles centimeter - less than half an inch millimeter - the width of a paper clip wire Volume calculated by multiplying L x W x H Liter the volume of a cube 1 dm (10 cm) on a side 1L = 1 dm3 so 1 L = 10 cm x 10 cm x 10 cm 1 L = 1000 cm3 1/1000 L = 1 cm3 1 mL = 1 cm3 Volume 1 L about 1/4 of a gallon - a quart 1 mL is about 20 drops of water or 1 sugar cube Mass Weight is a force. Mass is the amount of matter. 1 gram is defined as the mass of 1 cm3 of water at 4 ºC. 1000 g = 1000 cm3 of water 1 kg = 1 L of water Mass 1 kg = 2.5 lbs 1 g = 1 paper clip 1 mg = 10 grains of salt Converting k h D d c m how far you have to move on this chart, tells you how far, and which direction to move the decimal place. The box is the base unit, meters, Liters, grams, etc. Conversions k h D d c m convert 25 mg to grams convert 0.45 km to mm convert 35 mL to liters It works because the math works, we are dividing or multiplying by 10 the correct number of times. Which is heavier? it depends Density How heavy something is for its size. The ratio of mass to volume for a substance. D=M/V Independent of how much of it you have gold - high density air low density. Calculating The formula tells you how. Units will be g/mL or g/cm3 A piece of wood has a mass of 11.2 g and a volume of 23 mL what is the density? A piece of wood has a density of 0.93 g/mL and a volume of 23 mL what is the mass? Floating Lower density floats on higher density. Ice is less dense than water. Most wood is less dense than water. Helium is less dense than air. A ship is less dense than water. Density of water 1 g of water is 1 mL of water. density of water is 1 g/mL at 4ºC otherwise it is less 0ºC Measuring Temperature Celsius scale. water freezes at 0ºC water boils at 100ºC body temperature 37ºC room temperature 20 - 25ºC 273 K Measuring Temperature Kelvin starts at absolute zero (-273 º C) degrees are the same size C = K -273 K = C + 273 Kelvin is always bigger. Kelvin can never be negative. Temperature is different from heat. Temperature is which way heat will flow. (from hot to cold) Heat is energy, ability to do work. A drop of boiling water hurts, kilogram of boiling water kills. Units of heat are calories or Joules 1 calorie is the amount of heat needed to raise the temperature of 1 gram of water by 1ºC. A food Calorie is really a kilocalorie. How much energy is absorbed to heat 15 grams of water by 25ºC. 1 calorie = 4.18 J Elements & Compounds I. II. III. Element- simplest form of matter Elements can’t be separated Elements are the building block Smallest part is an atom Compounds I. II. III. IV. V. Compound- formed by 2 or more elements Substances that can be separated into simpler substances only by chemical reactions When broken down, the pieces have completely different properties than the compound Pure substances Represented by a formula Smallest part is a molecule Compound or Mixture Compound Mixture One kind of pieceMolecules More than one kind Molecule or atoms Making is a chemical change Making is a physical change Only one kind Variable composition What is it? 1. 2. 3. 4. 5. 6. 7. Element, Compound or Mixture Silver Orange Juice Ice Tea Potassium Chloride Oxygen Air Pine Tree Which is it? Mixture Element Compound Chemical Reactions One or more substances changing into a new substance Starting Substance- Reactant New Substance- Product Iron + Sulfur Iron Sulfide How do you know? I. II. III. IV. V. VI. 6 Ways to Tell Color Change Energy absorbed or released (temp change) Gas or Solid Produced Odor Precipitate (ppt)- solid that separates from solution Not easily reversed Conservation of Mass Law of Conservation of Mass- in a physical or chemical reaction, mass is neither created nor destroyed; it is conserved. All mass can be accounted for. Mass of the Reactants = Mass of Products Energy The ability to do work. Work - cause a change or move an object. Many types- all can be changed into the other. Types of energy Potential- stored energy Kinetic Energy- energy something has because its moving Heat- the energy that moves because of a temperature difference. Chemical energy- energy released or absorbed in a chemical change. Electrical energy - energy of moving charges Types of Energy Radiant Energy- energy that can travel through empty space (light, UV, infrared, radio) All types of energy can be converted into others. If you trace the source far enough back, you will end up at nuclear energy. Conservation of Energy Energy can be neither created or destroyed in ordinary changes (not nuclear), it can only change form. Its not just a good idea, its the law.