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Review: Standard Units of Measurement

Review: Standard Units of Measurement. Ms Fedor Arts and College Preparatory Academy. ChemCatalyst. How many centimeters (cm) are in a meter (m)? Convert 15 grams (g) into kilograms (kg). Upcoming Events. September 20 th : Lab practical Know lab equipment

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Review: Standard Units of Measurement

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  1. Review: Standard Units of Measurement MsFedor Arts and College Preparatory Academy

  2. ChemCatalyst • How many centimeters (cm) are in a meter (m)? • Convert 15 grams (g) into kilograms (kg)

  3. Upcoming Events • September 20th: Lab practical • Know lab equipment • Know how to read volume of a graduated cylinder • How to read/mass something on a balance • Give precise measurements • September 24th: Section 1 Quiz • Review sheet covering content on lab safety, equipment, matter, measurement

  4. Activity: Metric Measurement Goal: review units of measurement • Work with lab mates to measure the height of your desk • Write your measurement on the overhead • Find the average height of the desk

  5. SI Units (Systeme International d’ Unites) Units need to be the same in order to be comparable. Science uses metric units, which has a base of 10, making converting units very easy. Prefixes are used to differentiate between units.

  6. Metric Prefixes You Should Know

  7. example Kilogram • Kilo- = thousand • “thousand grams” Centimeter • Centi- = one hundreth • “one hundreth meter”

  8. ChemCatalyst What do these numbers have in common? • 2/2 • 6/6 • 1 • 1 x 100 They are all equal to one.

  9. Converting Units Units can be converted using a conversion factor: Conversion factor: relationship between the units Ex: 1000 grams (numerator) per kilogram (denominator) 1000g 1 kg Think of this line as meaning “per”

  10. Conversion Units Because 1000 g = 1 kg, 1000g = 1 kg = 1 1 kg 1000g This means that we can multiply any number by it, and the value will not change, because we are basically multiplying by one.

  11. Example Let’s say that we have to measure out 5 liters of a solution, but our graduated cylinder is divided into milliliters (mL). We need to know how many milliliters we need. What is the relationship between liters and milliliters?  There are 1000mL in 1L

  12. When using a conversion factor: • Always multiply across first (do not cross-multiply!!!) • Cancel the units that are on both the top and bottom that are the same 5 L x 1000 mL =5000 L mL = 5000 mL 1L 1 L known unit (unit we’re converting from) Unknown unit (unit we’re converting to)  We always put the unknown unit on the top (numerator), and the known unit on the bottom (denominator)

  13. Practice Question How many centimeters (cm) are in 6 meters (m)? 6 m x 100 cm = 600 m cm = 600 cm 1 m 1 m ? What would be the conversion?

  14. Practice: • Convert 30 grams into centigrams • 30 g x 100 cg = 3000 g cg = 3000 cg 1 g 1 g 2. Convert 20 cm into m • 20 cm x 1 m = 20 cm m = 0.20 m 100 cm 100 cm 3. Convert 2 Liters into milliliters • 2L x 1000 mL = 2000 L mL = 2000 mL 1L 1 L

  15. Assignment: Converting Units practice • Do the practice problems • Use the conversion factor method for the first section, then try your own method for the second section

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