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Welcome to: CHEMISTRY

Welcome to: CHEMISTRY. The Study of the Universe!. When Doing Labs. Use the Scientific Method – accepted method for scientists to explain how things work Steps: State Problem and Collect Data Formulate Hypothesis Perform Experiments.

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Welcome to: CHEMISTRY

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  1. Welcome to:CHEMISTRY The Study of the Universe!

  2. When Doing Labs • Use the Scientific Method – accepted method for scientists to explain how things work • Steps: • State Problem and Collect Data • Formulate Hypothesis • Perform Experiments

  3. Step 1: Collecting Data [Two Types]Quality vs. Quantity? Qualitative (Quality) • NO NUMBERS involved • Ex. The sky is blue • Ex. The solution is cloudy Quantitative (Quantity) • NUMBERS involved • Ex. The solution is 34.50 grams • Ex. Water boils at 100 degrees

  4. Step 2: Hypothesis • Hypothesis – a POSSIBLE explanation for why something happens • Observations are NOT hypotheses • Ex. the solution is cloudy (observation) • Ex. the solution is cloudy because it is contaminated (hypothesis)

  5. Step 3: Experiments • Use controls and variables • Control – the constant • Variable – the thing that changes in the experiment • Lake vs. Ocean • Perform multiple Trials – attempts at experiment

  6. When Measuring Liquids… • Meniscus – curve at upper surface of liquid • Measure liquids HERE

  7. Quick Quiz #1 • The scientist notes that there are 42 eggs in the basket. Is this a qualitative or quantitative measurement? • What is a variable? • When measuring volumes of liquids, what is the curved line that you use?

  8. Lab Safety

  9. Types of Chemicals • Flammables and Combustibles – chemicals that can catch on fire • Corrosives – things that damage/burn through skin tissue • Pressure – chemicals that are dangerous at different pressures

  10. Flammables • Ex. Bunsen Burners (used in this lab!) • Precaution: WEAR GOGGLES! • Similar but NOT the same as COMBUSTABLES – catch fire at HIGH temperatures

  11. Handling Boiling/Hot Chemicals • DON’T TOUCH WITH BARE HANDS! • USE TONGS or “Hot Hands”

  12. Corrosives • Corrosives = acids and bases that can damage skin • Precautions: WEAR GLOVES, PROTECTIVE CLOTHING (long-sleeves) AND GOGGLES

  13. If Corrosive Chemicals Get On Skin… • RINSE IMMEDIATELY • continuous running water (NOT SOAP) • Eyes – RINSE IMMEDIATELY for at least 5 minutes under eye wash.

  14. Broken Glass • Accidents happen (no, really) • Broken glass (beakers, test tubes, thermometers, etc) LET ME KNOW ASAP! • Move away from station until glass is cleared

  15. Warm Up #5

  16. The Metric System Converting Units

  17. Amurrica vs. The World Amurrica The Rest of the World Distance: Inches, Feet, Miles Volume: Cups, Quarts, Gallons Mass: Ounces, Pounds, Tons WHY DOES THIS STILL EXIST? Distance: Millimeters, Meters, Kilometers Volume: Milliliters, Liters, Kilometers Mass: Milligrams, Grams, Kilograms THIS IS WAY EASIER.

  18. The Metric System Prefixes

  19. Going from BIG to small • Ex: 145.8 Decimeters (dm) into Kilometers (km) • FOUR decimal places from DECI to KILO • Move Decimal FOUR PLACES LEFT • 145.8 dm = 0.01458

  20. Quick Quiz #3 Convert the following: • 34.67 mL = ____ L? • 4.903 hg = _____ dg? • John travelled a distance of 290480000 millimeters. How many kilometers is that?

  21. Density and Speed Density: Concentration of a substance in a given space • Mass over Volume (m/v) • Ex. g/mL, kg/L, etc. Speed: rate at which an object moves • Distance over Time (d/t) • Ex. m/s, km/hr, etc.

  22. Dimensional Analysis Intro. • Problem #1: Karla has a substance with a density of 4.68 g/mL. How many g/cL is that? • Problem #2: James was measuring the speed of a car in meters per second. If he found that a car was moving at the speed of 5.50 m/s, how many km/hr is that?

  23. On your Calculator: • 500 x 500 = 250000. (that’s a big number!) • .005 x .005 = 2.5-05 (WTF?) • Why does the second answer look like this?

  24. Scientific Notation • Scientific Notation – way of making REALLY big or REALLY small numbers easy to read. • General Form: M x 10n • M = number between 1 and 10 • n = number of decimal places you move

  25. Quick Quiz #1 Multiply 123456 x 7890 on your calculator • What was your answer? • Write your answer in scientific notation. Do the same for the following problems: • 98765 x 43210 = ? • 10000 x 892800 = ? • 90 x 9 = ?

  26. Review: WITH NUMBERS WAY BIGGER THAN 1 • MOVE DECIMAL TO THE LEFT • n VALUE WILL BE A POSITIVE NUMBER WITH NUMBERS WAY SMALLER THAN 1 • MOVE DECIMAL TO THE RIGHT • n VALUE WILL BE A NEGATIVE NUMBER

  27. Dimensional Analysis Part 1

  28. What does that mean? • Dimensional Analysis – Converting one thing to another • Used in chemistry (converting units of mass/distance/volume) • BUT YOU DO THIS IN REAL LIFE ALL THE TIME

  29. Convert the following: 60 sec. • How many seconds in a minute? • 1 minute = ___ seconds • How many quarters in a dollar? • 1 dollar = ___ quarters • How many points do you score in a touchdown? • 1 touchdown = ___ points 1 min. OR 60 sec. 1 min. $1 OR $1 OR

  30. Example Problem Julia measured the length of Catherine’s hair. She found out that her hair was 24 inches long. How many feet is that? First ask yourself: • What is your starting amount? • What are you converting to? • How many inches are in a foot?

  31. Reminder: UNITS • DO NOT LEAVE ANY NUMBER NAKED! IT NEEDS A UNIT. • GOAL: CANCELLING OUT UNITS • One unit label on top, the other on bottom Feet will cancel out (Feet x Feet) = Feet2 Feet

  32. System to Do This:DIMENSIONAL ANALYSIS • Starting amount, draw a line underneath it. • Draw a vertical line next to it. • One unit on top, other on bottom • Multiply stuff on top • Multiply stuff on bottom • Divide Top and Bottom

  33. Quick Quiz #2 Convert the following using Dimensional Analysis: • 12 feet = ___ inches? (1 foot = 12 inches) • 9 touchdowns = ___ points? (1 TD = 6 points) • 4 apples = ___ oranges? (1 apple = 3 oranges)

  34. Word Problems • Read the problems carefully • Underline important information (things with numbers) • Know what units you start with • Know what units you need to end with

  35. Example Problem • Steven was REALLY thirsty, so he wanted to buy some water bottles from Mr. Lockett. He ended up buying 4 water bottles. If each water bottle costs $2, how much money (in dollars) did he spend?

  36. Underline Important Info. • Steven was REALLY thirsty, so he wanted to buy some water bottles from Mr. Lockett. He ended up buying 4 water bottles. If each water bottle costs $2, how much money (in dollars) did he spend?

  37. Solve Using Dimensional Analysis Convert One Thing to Another 4 Water Bottles 2 Dollars 4 x 2 = 1 Water Bottle 1 Starting Materials (INCLUDE UNITS) = 8 Dollars

  38. Quick Quiz #3: SOLVE USING DIMENSIONAL ANALYSIS • Guadalupe was bored and wanted class to be over. Mr. Lockett said class was over in 90 minutes. How many hours is that? (1 hour = 60 minutes) • For some reason Esteban really wanted quarters. He gives the cashier a 5 dollar bill. How many quarters will he get from this 5 dollar bill? (1 dollar = 4 quarters)

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