Chemistry Item#5

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Item#5 of the Chemistry Diagnostic Test (c)2007 by Review Masters League, Inc.

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Chemistry Item#5

  1. 1. Chemistry Item #5 <ul><li>What is the density (g /mL) of a sample of ethyl alcohol if a 63.3 g sample occupies </li></ul><ul><li>80.0 mL? </li></ul><ul><ul><ul><ul><li>0.079 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>0.79 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1.26 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>12. </li></ul></ul></ul></ul>www.upcatreview.com
  2. 2. Forgot the formula? www.upcatreview.com
  3. 3. It’s not a hopeless case... www.upcatreview.com
  4. 4. You could follow two of our tips: www.upcatreview.com
  5. 5. First, www.upcatreview.com
  6. 6. www.upcatreview.com #31 Remove Extremes For numerical items, remove the extremes ( highest and lowest choice) and choose from the middle values.
  7. 7. This tip should only be used when you have no idea on how to solve the problem. www.upcatreview.com
  8. 8. Chemistry Item #5 <ul><li>What is the density (g /mL) of a sample of ethyl alcohol if a 63.3 g sample occupies </li></ul><ul><li>80.0 mL? </li></ul><ul><ul><ul><ul><li>0.079 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>0.79 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1.26 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>12.6 </li></ul></ul></ul></ul>www.upcatreview.com
  9. 9. You’re now left with two choices... www.upcatreview.com
  10. 10. Second tip: www.upcatreview.com
  11. 11. www.upcatreview.com #25 Educated Guess If you need to make a guess then it should be an educated guess . First, eliminate the answers that you know are wrong , then try your best to establish a basis for your choice.
  12. 12. With the two choices left, www.upcatreview.com
  13. 13. Chemistry Item #5 <ul><li>What is the density (g /mL) of a sample of ethyl alcohol if a 63.3 g sample occupies </li></ul><ul><li>80.0 mL? </li></ul><ul><ul><ul><ul><li>0.079 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>0.79 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1.26 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>12.6 </li></ul></ul></ul></ul>www.upcatreview.com
  14. 14. If you have the knowledge... www.upcatreview.com
  15. 15. ...that water is more dense than most alcohols. www.upcatreview.com
  16. 16. Perhaps because alcohols evaporate faster than water? www.upcatreview.com
  17. 17. And if you also have the knowledge... www.upcatreview.com
  18. 18. ...that the density of water is 1 g/ml www.upcatreview.com
  19. 19. Then, choice C is also eliminated... www.upcatreview.com
  20. 20. ...simply because it’s higher than 1. www.upcatreview.com
  21. 21. Chemistry Item #5 <ul><li>What is the density (g /mL) of a sample of ethyl alcohol if a 63.3 g sample occupies </li></ul><ul><li>80.0 mL? </li></ul><ul><ul><ul><ul><li>0.079 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>0.79 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1.26 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>12.6 </li></ul></ul></ul></ul>www.upcatreview.com
  22. 22. Thus, the answer is... www.upcatreview.com
  23. 23. B. 0.79 www.upcatreview.com
  24. 24. To verify, www.upcatreview.com
  25. 25. Density = mass ÷ volume Density = 63.3 ÷ 80.0 =0.79125 ≈ 0.79 www.upcatreview.com

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