Honors Chemistry 2020 2021 Anthony Petras Herndon High

Honors Chemistry 2020 -2021 Anthony Petras Herndon High

Day 3 • Welcome – remind me to record • Attendance (Hands Up Thing) • Pop Quiz (5 minutes) • Scientific Notation • Density • Percent Error • Metric Conversions • Another Pop Quiz? (5 minutes) • Homework

Pop Quiz • Solve each of the following. Give your answers using the correct number of significant figures. Solve without your notes or your calculator. (5 minutes) a. 29. 723 + 8. 0 = b. 12. 25 – 17. 7752 = c. 7 x 6 = d. 20. 000 ÷ 2. 0 = e. Convert 35°C to Kelvin f. Spell sophomore

Pop Quiz Answers • Solve each of the following. Give your answers using the correct number of significant figures. Solve without your notes or your calculator. (5 minutes) a. 29. 723 + 8. 0 = 37. 7 b. 12. 25 – 17. 7752 = -5. 53 c. 7 x 6 = 40 d. 20. 000 ÷ 2. 0 = 10. e. Convert 35°C to Kelvin = 308 K f. Spell sophomore - SOPHOMORE

Scientific Notation – Think you know it? • Solve each of the following. Use the proper number of significant figures. You may use a calculator. • (3. 691 x 107) x (2. 01 x 105) = • (2. 65 x 103) (4. 01 x 10 -3) =

Scientific Notation – Do you know it? • Solve each of the following. Use the proper number of significant figures. You may use a calculator. • (3. 691 x 107) x (2. 01 x 105) = 7. 42 x 1012 • (2. 65 x 103) (4. 01 x 10 -3) = 6. 61 x 105

Scientific Notation - Rules • When multiplying two numbers in scientific notation, ADD their power of 10 values. • For example: (3. 45 x 106) x (4. 3 x 105) = 14. 835 x 1011. But, we must also remember to express our answer using significant figures. • The final answer is 1. 5 x 1012 • When dividing numbers in scientific notation, SUBTRACT the denominator’s power of 10 value from the numerator’s power of 10 value. • For example: (2. 898 x 1012) (3. 45 x 1015) = 0. 840 x 10 -3 • Our final answer is: 8. 40 x 10 -4

Density • Density (d) is the ratio of the mass (m) of a substance to the volume (v) occupied by the substance. • Pure water is used as the standard in measuring density. The density of pure water is 1. 0 g/m. L. • If a substance has a density less than water, it will float; if a substance has a density greater than water, it will sink. • Mass is expressed in grams (g). Volume is expressed in either milliliters (m. L) or cubic centimeters (cc or cm 3). Thus, density can be expressed as g/m. L or g/cm 3.

Density Example • Example: A piece of wood has a volume of 3350 cm 3. If the density of the wood is 0. 512 g/m. L, what is its mass? • Solution: 1720 g

Density Practice Problems - #1 & #2 • Cerium sulfate has a density of 3. 17 g/cm 3. Calculate the volume of 599 g of this substance. • What is the density of a piece of cork that has a mass of 0. 650 g and a volume of 2. 7 cm 3?

Density Practice Problems - #1 & #2 Answers • Cerium sulfate has a density of 3. 17 g/cm 3. Calculate the volume of 599 g of this substance. 189 cm 3 • What is the density of a piece of cork that has a mass of 0. 650 g and a volume of 2. 7 cm 3? 0. 24 g/m. L

Percent Error Calcalulate the Percent Error, given the following values: Experimental (Student) Value: 29. 5 g/m. L, Theoretical (Accepted Scientific) Value: 28. 0 g/m. L

Percent Error Calcalulate the Percent Error, given the following values: Experimental (Student) Value: 29. 5 g/m. L, % Error: 5. 4% Theoretical (Accepted Scientific) Value: 28. 0 g/m. L

Metric Conversion • Any method that works is acceptable. I will demonstrate a couple methods. Factor Prefix Symbol 1 x 10 tera. T • You should take notes on both. 1 x 10 giga. G 1 x 10 mega. M • Clever use of metric prefixes. 1 x 10 kilok 12 9 6 3 1 x 102 1 x 101 1 x 100 1 x 10 -1 1 x 10 -2 1 x 10 -3 1 x 10 -6 1 x 10 -9 1 x 10 -10 1 x 10 -12 hectodecabase unit decicentimillimicronanoangstrom pico- h D --d c m μ n Å p

Metric Conversion Examples • Convert 35. 5 centigrams to kilograms. • Subtraction method: • Dimensional Analysis method:

Metric Conversion Examples • Convert 9. 15 gigaliters to milliliters. • Subtraction method: • Dimensional Analysis method:

Another Pop Quiz? • Solve each of the following. Give your answers using the correct number of significant figures. Solve without your notes or your calculator. (5 minutes) a. 69. 723 + 7. 3 = b. 15. 25 – 810. 7752 = c. 6 x 9 = d. 18. 000 ÷ 6. 00 = e. Convert -73. °C to Kelvin

Another Pop Quiz? - Answers • Solve each of the following. Give your answers using the correct number of significant figures. Solve without your notes or your calculator. (5 minutes) a. 69. 723 + 7. 3 = 77. 0 b. 15. 25 – 810. 7752 = -795. 53 c. 6 x 9 = 50 d. 18. 000 ÷ 6. 00 = 3. 00 e. Convert -73. °C to Kelvin = 200. K

Homework • Review Power Point • Complete the following Chapter 1 quizzes on Sartep by Monday 9/21 3 pm: (more will be added after next lesson) 1. 2. 3. 4. 5. 6. 7. density quiz metric conversion quiz metric values quiz percent error quiz scientific notation calculation quiz scientific notation quiz 2 • Resources: http: //www. sartep. com/chem/worksheets/worksheet_record. cfm? wslink=1_03. pdf