W1 Example 2 Answers
- 1. 2a How many grams are there in 3 moles of H2O?
- 2. 2a • Calculate how many grams are in one mole by multiplying the number of atoms of each element by their mass:
- 3. 2a • Calculate how many grams are in one mole by multiplying the number of atoms of each element by their mass: 1 mole = 2 x 1.0079 + 1 x 15.999 = 18.015g
- 4. 2a • Calculate how many grams are in one mole by multiplying the number of atoms of each element by their mass: 1 mole = 2 x 1.0079 + 1 x 15.999 = 18.015g • Multiply this by the number of moles in the sample:
- 5. 2a • Calculate how many grams are in one mole by multiplying the number of atoms of each element by their mass: 1 mole = 2 x 1.0079 + 1 x 15.999 = 18.015g • Multiply this by the number of moles in the sample: 3 x 18.015 = ퟓퟒ. ퟎퟒퟒퟒ퐠
- 6. 2b Calculate the number of moles of calcium in a 1kg rock sample, if the rock is 411 ppm calcium.
- 7. 2b • Convert ppm to g per kg:
- 8. 2b • Convert ppm to g per kg: 441ppm = 441μg per g
- 9. 2b • Convert ppm to g per kg: 441ppm = 441μg per g 441,000μg per kg = 0.441g per kg
- 10. 2b • Convert ppm to g per kg: 441ppm = 441μg per g 441,000μg per kg = 0.441g per kg • Divide by the mass of one mole of calcium:
- 11. 2b • Convert ppm to g per kg: 441ppm = 441μg per g 441,000μg per kg = 0.441g per kg • Divide by the mass of one mole of calcium: 1 mole Ca = 40.078g
- 12. 2b • Convert ppm to g per kg: 441ppm = 441μg per g 441,000μg per kg = 0.441g per kg • Divide by the mass of one mole of calcium: 1 mole Ca = 40.078g 0.441 40.078 = ퟎ. ퟎퟏퟐ퐦퐨퐥 퐂퐚
- 13. 2c Seawater contains around 10.8 ppt (parts per thousand) sodium. What is this in mol/kg Na?
- 14. 2c • Convert ppt to g per kg:
- 15. 2c • Convert ppt to g per kg: 10.8ppt = 10.8g per kg
- 16. 2c • Convert ppt to g per kg: 10.8ppt = 10.8g per kg • Divide by the mass of sodium:
- 17. 2c • Convert ppt to g per kg: 10.8ppt = 10.8g per kg • Divide by the mass of sodium: 1 mole Na = 22.99g
- 18. 2c • Convert ppt to g per kg: 10.8ppt = 10.8g per kg • Divide by the mass of sodium: 1 mole Na = 22.99g 10.8 22.99 = ퟎ. ퟒퟕ퐦퐨퐥퐤퐠−ퟏ 퐍퐚
- 19. 2d If all river water contained 45 ppb PO43-, and flowed into the ocean at 3.6 x 1016 kg/year, what would be the flux of PO43- into the ocean in mol/yr? (Hint: First convert PO43- from ppb to molkg-1.)
- 20. 2d • Convert from ppb to moles per kg:
- 21. 2d • Convert from ppb to moles per kg: 45ppb = 45ng per g = 45μg per kg
- 22. 2d • Convert from ppb to moles per kg: 45ppb = 45ng per g = 45μg per kg 1 mole PO4 3 − = 30.974 + 4 15.999 = 94.97g
- 23. 2d • Convert from ppb to moles per kg: 45ppb = 45ng per g = 45μg per kg 1 mole PO4 3 − = 30.974 + 4 15.999 = 94.97g 45 x 10−6gkg−1 94.97g = 4.74 x 10−7molkg−1
- 24. 2d • Convert from ppb to moles per kg: 45ppb = 45ng per g = 45μg per kg 1 mole PO4 3 − = 30.974 + 4 15.999 = 94.97g 45 x 10−6gkg−1 94.97g = 4.74 x 10−7molkg−1 • Multiply by the flux of water:
- 25. 2d • Convert from ppb to moles per kg: 45ppb = 45ng per g = 45μg per kg 1 mole PO4 3 − = 30.974 + 4 15.999 = 94.97g 45 x 10−6gkg−1 94.97g = 4.74 x 10−7molkg−1 • Multiply by the flux of water: 4.74 x 10−7molkg−1 x 3.6 x 1016kgyr−1 = ퟏ. ퟕퟏ 퐱 ퟏퟎퟏퟎ퐦퐨퐥퐲퐫−ퟏ 퐏퐎ퟒퟑ−