1 / 18

Tips and Tricks for Math W/OUT Calculator

Tips and Tricks for Math W/OUT Calculator. And there will be even more to come on this throughout the year as we encounter new types of problems!. Estimation!. Round/estimate numbers so that they work well together for easy math

geary
Download Presentation

Tips and Tricks for Math W/OUT Calculator

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. Tips and Tricks for Math W/OUT Calculator And there will be even more to come on this throughout the year as we encounter new types of problems!

  2. Estimation! • Round/estimate numbers so that they work well together for easy math •  For example, say PV = nRT boils down to (2.881)(1.99) = (x)(0.08206)(298) • That’s really close to (3)(2) = (x)(0.1)(300) • Which is x = 6/30 = 0.2 • Although exactly 0.2 is not likely to be an answer, answer choices will be given in such a way where it should be obvious which one is the correct one. (The actual answer is 0.234 – not bad!) • Out of time/can’t find easy numbers that work together? Round everything to start with 1! (100, 10, 1, 0.1, 0.01, etc) • In our example: (1)(1) = (x)(0.1)(100) • x = 1/10 = 0.1

  3. Canceling • When using dimensional analysis cancel out/simplify what you can in the fractions • You may need to estimate numbers so they can cancel • Examples: 0.167 158

  4. Working with Decimals • Dividing • Moving the decimal the same number of spots in the numerator and denominator will not change the value/ratio of the fraction • Example: = • Multiplying • Multiply the values together with disregard for the decimal • Your final, correct answer will have the total number of decimal places from the factors that are being multiplied • Example: 0.0012 x .03 = 22 = 0.000036 = 3.6 x 10-5

  5. Working with Scientific Notation/Exponents • Multiplying: • Multiply coefficient values • Add the exponent values • Example: (6.022 x 1023)(3.0 x 10-5) = • Dividing: • Divide coefficient values • Subtract the exponent values • Example: = • Put number back into correct scientific notation if necessary • If you make the coefficient bigger, make the exponent smaller, and vice versa: 83 x 10-16 = 8.3 x 10-15 18 x 1018 1.8 x 1019 8.3 x 10-15

  6. Things that will be beneficial to know • Basic multiplication tables up to 12 • Perfect squares up to 12 • Long multiplication and long divisions • Working with powers of 10: • Divided by ten, decimal point moves to the left one place. • Multiple by ten, decimal point moves to the right one place. • Divide by powers of ten (100 = 102, 1000 = 103, etc) move the decimal point to the left the same number of spaces as the power of ten. • Multiple by powers of ten (100 = 102, 1000 = 103, etc) move the decimal point to the right the same number of spaces as the power of ten.

  7. Things that will be beneficial to know • Fractions and their decimal values

  8. Examples • If 200. mL of 0.80 M MgCl2(aq) is added to 600. mL of distilled water, what is the concentration of Cl-(aq) in the resulting solution? A. 0.20 M B. 0.30 M C. 0.40 M D. 0.60 M E. 1.2 M

  9. Examples • If 200. mL of 0.80 M MgCl2(aq) is added to 600. mL of distilled water, what is the concentration of Cl-(aq) in the resulting solution? A. 0.20 M B. 0.30 M C. 0.40 M D. 0.60 M E. 1.2 M

  10. How many grams of calcium carbonate, CaCO3, contain 48 grams of oxygen atoms? (The molar mass of CaCO3 is 100.088 g/mol.) (a) 41 grams(b) 50. grams(c) 62 grams(d) 88 grams(e) 100 grams

  11. How many grams of calcium carbonate, CaCO3, contain 48 grams of oxygen atoms? (The molar mass of CaCO3 is 100.088 g/mol.) (a) 41 grams(b) 50. grams(c) 62 grams(d) 88 grams(e) 100 grams

  12. When a 1.25-gram sample of limestone, that contains CaCO3 and inert impurities was dissolved in acid, 0.22 grams of CO2 was generated. What was the percent of CaCO3 by mass in the limestone? (The molar mass of CaCO3 is 100.088 g/mol.) (a) 20%(b) 40%(c) 67%(d) 80%(e) 100%

  13. When a 1.25-gram sample of limestone, that contains CaCO3 and inert impurities was dissolved in acid, 0.22 grams of CO2 was generated. What was the percent of CaCO3 by mass in the limestone? (The molar mass of CaCO3 is 100.088 g/mol.) (a) 20%(b) 40%(c) 67%(d) 80%(e) 100%

  14. If 70. grams of K3PO4 (molar mass 210 g/mol) is dissolved in enough water to make 250 milliliters of solution, what are the concentrations of the potassium and the sulfate ions?

  15. If 70. grams of K3PO4 (molar mass 210 g/mol) is dissolved in enough water to make 250 milliliters of solution, what are the concentrations of the potassium and the sulfate ions?

  16. A 2 L container will hold about 6 g of which of the following gases at 0oC and 1 atm? (a) SO2 (b) N2 (c) CO2 (d) C4H8 (e) NH3

  17. A 2 L container will hold about 6 g of which of the following gases at 0oC and 1 atm? (a) SO2 (b) N2 (c) CO2 (d) C4H8 (e) NH3

  18. Poster Instructions With your table group: • Work your one assigned problem from p. 25-26 in four various ways: • Use a calculator for to set-up and solve using full given values: check your answer with Ms. Lestik when done! • Develop 3 various methods of no calculator, and decide as a team which you think is most effective for your problems • Create a poster demonstrating the four various methods used, which will include the following: • The question, and the names of each group member • All four methods of solving the question • Your explanation for which math-free way was best and why! • At the end of class we will have a gallery walk so you can see how to work the other problems and maybe learn some new tips and tricks for math w/out a calculator!

More Related