1 / 73

Chemistry Unit 1

Chemistry Unit 1. Warm-Up (8/10). Identify the independent and dependent variable: Randall decided that he wanted to test the effect that salinity had on his two goldfish. (salinity= amount of salt dissolved in water) What two countries use the Imperial System of measurement?

rufusa
Download Presentation

Chemistry Unit 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ChemistryUnit 1

  2. Warm-Up (8/10) • Identify the independent and dependent variable: Randall decided that he wanted to test the effect that salinity had on his two goldfish. (salinity= amount of salt dissolved in water) • What two countries use the Imperial System of measurement? • Give me two examples of a time you would use measurements.

  3. Learning Goal • I will learn the basic units of measurement and how to do decimal conversions.

  4. What is the SI system? • The International System of Units is the system of measurement used worldwide. • It is commonly known as the metric system. Why use it? • It allows scientists, mathematicians, and astronomers share data and discoveries across language barriers. • Fun fact: There is an International Treaty of the Meter which was signed in Paris on May 20, 1875 by seventeen countries, including the United States and is now celebrated around the globe as Meter day.

  5. SI Base Units These 7 basic units allow us to measure everything we find valuable and important. Even if we use other forms of measurement, we can easily convert these into SI units by following the conversion table.

  6. Standards of Measurement • Length is the distance between two points. We measure our length from our toes to our head. • Volume is the amount of space an object takes up. • Time is the interval between two occurring events.

  7. Standards of Measurement • Mass is the amount of matter in an object. Mass is not weight. • Weight is a force exerted by gravity, whereas mass is how much material is within an object.

  8. How do we measure in SI units? • When you measure in SI you will always start with a base. Then you will add a prefix to be more precise. All the prefixes are based on multiples of 10.

  9. Step 1. Identify your starting unit and the unit you are converting too. Step 2. Count how many spaces away the new unit is from your starting unit. Step 3. Are you moving up or down? (If you move up you move the decimal left, if you move down you move the decimal right) Step 4. Move the decimal over that many spaces and in the direction indicated in step 3. Don’t forget to add units to end your ending number. Example: We are going to start with 1 meter and we want to get to millimeters. Starting unit = 1.0 m Ending unit= mm 3 spaces Down, moving the decimal right. 1.0 m --> 1.0 0 0 = 1000 mm How to Convert Using the Decimal in 4 Steps

  10. How do we measure in SI units? • Step 1. Identify your starting unit and the unit you are converting too. • Step 2. Count how many spaces away the new unit is from your starting unit. • Step 3. Are you moving up or down? • (If you move up you move the decimal left, if you move down you move the decimal right) • Step 4. Move the decimal over that many spaces and in the direction indicated in step 3. • Don’t forget to add units to end your ending number. Together: • Convert 6.0 meters to kilometers

  11. Warm-up (8/13) • Why do you think that the stuff in the cup is not mixing together? (I want an educated explanation) • Solve for Volume using D=M/V. V=3.5 and M=9.

  12. Learning Goal • I will learn about density and how to rearrange equations.

  13. Discuss with your partner Which is heavier, 1kg of feathers or 1 kg of gold?

  14. Now think about how big a bag of feathers would be and how big a bag of gold is? • The reason they are different in size is because of density. Density

  15. Density • Density basically tells us how compact an item is, • It is the mass of an object divided by the volume. This is a unit obtained from other units – a derived unit • Density= • Units is (kg/)

  16. Density practice • What is the mass of this scale? Do not forget units! • Do not overthink it! 25.0

  17. Density practice What is the volume of the rock? Do not forget your units!

  18. Calculating Density • Calculate: What is the density of an object that has a mass of 25 kg and a volume of 5 ml? • You may use a calculator if you need one. Don’t forget your units. • d = 25g  5mL • d = 5g/mL

  19. Together • You have a rock with a volume of 15cm3 and a mass of 45 g. What is its density?

  20. How do you rearrange an equation? • First there are rules: • RULE #1: you can add, subtract, multiply and divide by anything, as long as you do the same thing to both sides of the equals sign. In an equation, the equals sign acts like the center of a balance: if you add 5 of something to one side of the balance, you have to add the same amount to the other side to keep the balance steady. The same thing goes for an equation - doing the same operation to both sides keeps the meaning of the equation from changing. • RULE #2: to move or cancel a quantity or variable on one side of the equation, perform the "opposite" operation with it on both sides of the equation.

  21. Let’s try it without the equation! • 15X + 2 = 10X + 4 (whatever you do to one side you have to do to the other)

  22. Now let’s try a harder one! • + 4 = 9

  23. What Happens When You Have to Rearrange the Equation? Steps: • Identify mass, volume, and density • Determine what you do not have a value for. • Rearrange the equation if you have too. • Plug and chug

  24. When calculating for a variable we saw we have to isolate it! Try isolating V when we have mass and density given to us. D= 20 M=5 V=? 20=

  25. Let’s do it without numbers! • Get M on the left side of the equal side. • M= ?

  26. Wrap-up • On your whiteboards, write the formula for density as if you were solving for mass. • Convert 780 mm to hm.

  27. Independent Practice • Glue the SI Unit and Density worksheet in your notebook. • Independently, spend time working on the SI Unit and Density worksheet

  28. Warm up (8/14) Think-Write-Pair-Share • What is the density of carbon dioxide gas if 0.196 g occupies a volume of 100 mL? • An irregularly shaped stone was lowered into a graduated cylinder holding a volume of water equal to 2.0 mL. The height of the water rose to 7.0 mL. If the mass of thestonewas 25 g, what was its density?

  29. Learning Goal • I will learn about significant figures and how to calculate them.

  30. Game Time • Try to hit the target.

  31. Accuracy and Precision • Precision= The ability to be reproducible • Accuracy= The quality of being near the desired value. • You can be accurate and precise!

  32. Why does this matter? • Precision and accuracy are two ways that scientists think about error. • Accuracy refers to how close a measurement is to the true or accepted value. • Precision refers to how close measurements of the same item are to each other. • The best quality scientific observations are both accurate and precise.

  33. How do scientists be both precise and accurate? • The precision of the measurement is indicated by the number of digits reported. • SCIENTISTS SHOW ACCURACY AND PRECISION BY USING SIGNIFICANT FIGURES. • Significant figures= include all known digits plus one estimated digit.

  34. Significant Figures Example: • Example: Say the end of a rod falls between 5.2 cm and 5.3 cm. We would estimate, based on where it is on the ruler, that it was 5.22 cm or 5.23 cm. Either way we have two digits known and one estimated.

  35. Significant Figures • Measurements can be really precise if we have a lot of numbers, but they might not be accurate. This is why there are rules! • Rules: • Nonzero numbers are ALWAYS significant • 72.3 g has three • Zeros between nonzero numbers are ALWAYS significant • 60.5 g has three • All final zeros to the right of the decimal are significant • 6.20 has three • 4) Placeholder zeros are not significant. To remove placeholder zeros we will write it in scientific notation. • 0.0235g and 4320 g each has three • 5) Exact numbers and conversion factors have unlimited significant figures • Ex. 30 students, 1 min= 60 sec

  36. Guided Practice • Determine the number of significant figures: • 0.0546 g • 298.206 m • 102000 mm • 0.003145 L • 7.847000 hg • 3, because leading zeros are never significant • 6, sandwiched zeros are significant • 3, trailing zeros are only significant if there is a decimal • 4, because leading zeros are never significant • 7, because there is a decimal making the zeros significant

  37. Together In your tables determine how many significant figures there are. • 508.0 L • 820,400.0 L • 0.049450 s • 0.000482 mL • 0.0084 mL

  38. ADDING, SUBTRACTING, MULTIPLYING, AND DIVIDING When adding, subtracting, multiplying, and dividing you follow the slowest member of the team. • !!!Your answer cannot be MORE precise than the least precise measurement!!! • Examples: • 9.8033 m – 3.04 m = • 6.2089 mg x 30 mm = • 25.00 L /5.0 L =

  39. On Your Whiteboard… • Do the following problems… • 0.042 m + 1.33 m = • 8.90 g – 4.555 g = • 60.0 L / 5 L = • 7.8 cm x 3.5 cm = • 5.63 +4.245 – 8.9 =

  40. Wrap- up • In your groups take a minute, and explain why significant figures are important? • Why do we use them?

  41. Warm-up (8/15 & 8/16) • How many significant figures are in each problem? • 1) 3.0980 = • 2) 4.0 x 5.66 = • 3) 45.0 / 15.0 = • 4) 4.56 + 2.312 – 5.6=

  42. Warm up (8/17) • List the steps of the scientific method • Convert 3.4 hg to g • You have a graduated cylinder with 6.0 mL of water in it. You drop a rock into the cylinder and the water rises to 15 mL. If the rock weighed 10 g, what is its density?

  43. At Your Tables • Work on the last two papers I gave you. The SI Units and Density and then the calculating Significant Figures. • When you’re finished turn in the SI units and Density, and then glue in your significant figures paper.

  44. Warm-up (8/20) • What is scientific notation? • You have a rock with a volume of 15cm3 and a mass of 45 g. What is its density? Proper significant figures.

  45. Do you know how many combinations/choices you have when solving a rubix cube? The answer is 43,000,000,000,000,000,000 quintillion possible moves.

  46. Powers of 10 • We know that when we multiply by 10 the number increases ten fold. • We can have 1,000 or 10,0000 or maybe 1,000,000. • We can write this with the powers of 10. • 10 x 10 x 10 x 10 =

  47. Scientific Notation • This how we can simply show that a number with LOTS of zeros is really small or really large. • This is also how we can have the CORRECT amount of significant figures without changing the value of the number.

  48. Scientific Notation • Scientific Notation can also be called standard form. It is a special way of writing numbers.

  49. How Does it Work?

  50. What if we are using decimals or digits that aren’t just zero?

More Related