Stoichiometry

# Stoichiometry

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## Stoichiometry

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1. Stoichiometry

2. Stoichiometry comes from the Greek words for “element” and “measure”. Stoichiometry takes information for one element/compound in a reaction and allows for the calculation of the amount of a different element/compound in the same reaction. Obviously the place to start is…

3. Predict and write a balanced chemical equation.

4. Predict and write a balanced chemical equation. Start a RR track and convert the given information to moles (if not already as moles).

5. Predict and write a balanced chemical equation. • Start a RR track and convert the given information to moles (if not already as moles). • Use the molar mass (from the PT) to change grams → moles

6. Predict and write a balanced chemical equation. • Start a RR track and convert the given information to moles (if not already as moles). • Use the molar mass (from the PT) to change grams → moles • Use 6.022 x 1023 to change atoms/molecules/formula units → moles

7. Predict and write a balanced chemical equation. • Start a RR track and convert the given information to moles (if not already as moles). • Use the molar mass (from the PT) to change grams → moles • Use 6.022 x 1023 to change atoms/molecules/formula units → moles • Use 22.41 L (for gases only) to change L → moles

8. Predict and write a balanced chemical equation. • Start a RR track and convert the given information to moles (if not already as moles). • Use the molar mass (from the PT) to change grams → moles • Use 6.022 x 1023 to change atoms/molecules/formula units → moles • Use 22.4 L (for gases only) to change L → moles • For water and dilute solutions, 1 mL = 1 g

9. Convert the moles of the given to moles of the unknown using the mole ratio from the balanced chemical equation • Mole # of unknown • Mole # of known

10. Convert the moles of the given to moles of the unknown using the mole ratio from the balanced chemical equation • Mole # of unknown • Mole # of known • 4. Convert the moles of the unknown to the desired unit (see possible conversion factors in step 2)

11. Example: Potassium is reacted with phosphoric acid Step 1: What is step 1, always ?

12. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g)

13. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams?

14. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Always start by copying the given information!

15. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? What MUST go here?

16. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Where do we always go to get grams information?

17. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Why “1 mole”?

18. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? What MUST go here?

19. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? What compound/ element are we looking for?

20. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? What compound/ element are we looking for?

21. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Where can we find a mole ratio for these?

22. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams?

23. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? REDUCE?

24. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? What MUST go here?

25. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? What specific information about potassium phosphate is wanted?

26. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Where do we always go to get grams information?

27. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Why “1 mole”?

28. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? How should this be calculated?

29. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? 125 × 2 × 136 ÷ 39.1 ÷ 6 = 144.928

30. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 125 g of potassium, how much potassium phosphate can be produced, in grams? Why 3 Sig Digs? 125 × 2 × 136 ÷ 39.1 ÷ 6 = 144.928

31. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

32. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

33. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

34. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

35. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

36. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

37. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

38. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

39. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed?

40. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed? 35.4 × 2 × 6.022E23 ÷ 39.1 ÷ 6 = 1.81738E23

41. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we started with 35.4 g of potassium, how many formula units of phosphoric acid are needed? 1.82 × 1023 formula units H3PO4

42. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

43. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

44. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

45. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

46. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

47. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

48. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

49. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?

50. Example: Potassium is reacted with phosphoric acid Step 1: 2H3PO4(aq) + 6K(s) → 2K3PO4(aq) + 3H2(g) If we were able to collect 6.92 L of hydrogen gas, how many grams of phosphoric acid was used?