1. Foundations of Chemistry 2

2. A. Chemistry Calculations Most calculations can be done most easily using the ________________________. This method allows us to use the units in order to plan and _________ the problem. Examples: 1) How many seconds are there in 652 minutes?

3. 2) How many seconds are there in 0.35 years? 3) How many weeks are there in 4.1 years?

4. 4) How many miles are there in 25 m? 5) How many m/s are there in 12.5km/h?

5. B. The Mole (Chemical Amount) Because ______________ ______________ are so small, chemists use a more convenient method…the _________. A mole is the ___________ of an element/compound in grams (AKA. ___________)

6. 1a) What is the mass of 1 mole of Carbon ?

7. b) What is the mass of 1 mole of zinc?

8. c) What is the mass of 1 mole of water?

9. 2a) Find the molar mass of NaClO 3.

10. b) Find the molar mass of copper (II) phosphate.

11. 3a) Calculate the mass of 4.1 moles of Mg.

12. b) How many moles are there in 156.3g of aluminum?

13. c) Find the mass of 6.2 moles of tin (IV) acetate.

14. d) How many moles are there in 235.5 g of ammonium dichromate.

15. C. Avagadro’s Number Just as a dozen represents 12, a mole represents ________________ particles, molecules, or atoms of that substance. This number is extremely large.

16. Calculations (One-Step) a)How many moles of O are in 1.60 × 10 23 molecules? b)How many moles of K are in 3.98 × 10 23 molecules?

17. c) How many moles of NaCl are in 1.0 x 10 3 particles? d) How many particles are in 1.50 moles of CaCO 3 ?

18. e) How many particles are there in 0.81 moles of FeO?

19. Calculations (Two Step)

20. a)How many grams of water are there in 3.01 × 10 23 particles? b)How many grams of KCl are there in 15,000 particles?

21. c) How many particles are there in 15.2 g of dinitrogen pentoxide? d) How many particles are there in 30.0 g of KMnO 4 ?

22. D. Volume of a Mole of Gas Always measured at STP (___________ _____________________________). –This is _____ and _________ (____________) At STP, 1 mole of any gas occupies ______ of space.

23. 22.4 L of gas is also equivalent to ____________________. The mass only vary according to the molar mass. –_________________________ _________________________ _________________________.

24. Calculations a)Determine the volume of 0.500 moles of hydrogen gas at STP. b)How many moles are in 40.5 L of chlorine gas?

25. c) Determine the mass of 36.0 L of carbon dioxide gas. d) How many molecules are there in 4.5g of butane?

26. E. Percent Composition The percent by _________ of each element in a compound. The percentages must always add up to ______. The formula that we use is:

27. Sample: Mewelde Moore (209 lbs), Donnie Avery (200. lbs), and Andrew Luck (234 lbs) are in a huddle. Calculate the mass percentage that each of these guys have.

28. Calculations a)An 8.20g piece of Mg combines with 5.40g of O to form a compound. What is the percent composition?

29. b) Calculate the percent composition of ethane (C 2 H 6 ).

30. c) Calculate the mass of carbon in 95g of ethanol (C 2 H 5 OH).

31. d) What mass of aluminum would be in 38.35 g of aluminum hydroxide?

32. F. Empirical Formulas Gives the lowest _______________ of the elements in a compound. We can do this by finding and using the number of ___________.

33. Calculations a)What is the empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen?

34. b) Calculate the empirical formula for 71.72% chlorine, 16.16% oxygen, and 12.12% carbon.

35. c) What is the empirical formula for a compound with 38.67% carbon, 16.23% hydrogen, and 45.10% nitrogen?

36. G. Molarity Is a measure of ______________. The amount of a ________ that is dissolved in a given amount of _________ (usually 1L of water). –Dilute solution – _____________. –Concentrated solution – _____________.

37. Calculations a)What is the molarity of 10.0g of H 2 SO 4 in 5.00 x 10 2 mL? b)How many grams of copper (II) sulphate are in 0.75L of a 0.40 mol/L solution?

38. c) How many grams of iron (III) chloride are needed to make 250mL of a 0.100M solution? d) What is the molarity if 25g of sodium phosphate are added to 25mL of water?