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W1 Example 1 Answers

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The document contains solutions to 3 chemistry problems: 1) A 50g rock sample with 80ppm copper contains 4 mg of copper. 2) A 2g seawater sample with 850ng silicon has a silicon concentration of 1.7 ppm. 3) With the ocean's average salinity of 35 ppt and mass of 1.4x1021 kg, it contains 4.9x1020 kg of salt.

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1a How many milligrams of copper are there in a 50g rock sample of 80ppm copper? Click to navigate Click to enlarge
1a ? Work out this proportion in grams:
1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g
1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample:
1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample: 80¦Ìg x 50 = 4000¦Ìg
1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample: 80¦Ìg x 50 = 4000¦Ìg ? Convert micrograms to milligrams:
1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample: 80¦Ìg x 50 = 4000¦Ìg ? Convert micrograms to milligrams: 4000 1000 = ???
1b A 2g sample of seawater contains 850ng silicon. What is the silicon concentration in ppm?
1b ? Convert to ¦Ìg per g to find the ppm of 1g:
1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg
1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg 0.85¦Ìg in 1g = 0.85ppm
1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg 0.85¦Ìg in 1g = 0.85ppm ? Multiply by the mass of the sample:
1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg 0.85¦Ìg in 1g = 0.85ppm ? Multiply by the mass of the sample: 0.85¦Ìg in 2g = 2 x 0.85 = ?. ????
1c Salinity is a unitless measurement representing grams of salt per 1000g of seawater (i.e. ppt of salt). Considering the ocean has an average salinity of 35, and contains roughly 1.4 x 1021kg of water, how much salt is there in the ocean in kg?
1c ? Convert this to kg of salt per kg of water:
1c ? Convert this to kg of salt per kg of water: 35ppt = 35mg per g = 35g per kg = 0.035kg per kg
1c ? Convert this to kg of salt per kg of water: 35ppt = 35mg per g = 35g per kg = 0.035kg per kg ? Multiply by the mass of the sample:
1c ? Convert this to kg of salt per kg of water: 35ppt = 35mg per g = 35g per kg = 0.035kg per kg ? Multiply by the mass of the sample: 0.035 x 1.4 x 1021 = ?. ? ? ??????

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W1 Example 1 Answers

  • 1. 1a How many milligrams of copper are there in a 50g rock sample of 80ppm copper? Click to navigate Click to enlarge
  • 2. 1a ? Work out this proportion in grams:
  • 3. 1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g
  • 4. 1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample:
  • 5. 1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample: 80¦Ìg x 50 = 4000¦Ìg
  • 6. 1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample: 80¦Ìg x 50 = 4000¦Ìg ? Convert micrograms to milligrams:
  • 7. 1a ? Work out this proportion in grams: 80ppm = 80¦Ìg per g ? Multiply by the mass of the sample: 80¦Ìg x 50 = 4000¦Ìg ? Convert micrograms to milligrams: 4000 1000 = ???
  • 8. 1b A 2g sample of seawater contains 850ng silicon. What is the silicon concentration in ppm?
  • 9. 1b ? Convert to ¦Ìg per g to find the ppm of 1g:
  • 10. 1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg
  • 11. 1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg 0.85¦Ìg in 1g = 0.85ppm
  • 12. 1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg 0.85¦Ìg in 1g = 0.85ppm ? Multiply by the mass of the sample:
  • 13. 1b ? Convert to ¦Ìg per g to find the ppm of 1g: 850ng = 0.85¦Ìg 0.85¦Ìg in 1g = 0.85ppm ? Multiply by the mass of the sample: 0.85¦Ìg in 2g = 2 x 0.85 = ?. ????
  • 14. 1c Salinity is a unitless measurement representing grams of salt per 1000g of seawater (i.e. ppt of salt). Considering the ocean has an average salinity of 35, and contains roughly 1.4 x 1021kg of water, how much salt is there in the ocean in kg?
  • 15. 1c ? Convert this to kg of salt per kg of water:
  • 16. 1c ? Convert this to kg of salt per kg of water: 35ppt = 35mg per g = 35g per kg = 0.035kg per kg
  • 17. 1c ? Convert this to kg of salt per kg of water: 35ppt = 35mg per g = 35g per kg = 0.035kg per kg ? Multiply by the mass of the sample:
  • 18. 1c ? Convert this to kg of salt per kg of water: 35ppt = 35mg per g = 35g per kg = 0.035kg per kg ? Multiply by the mass of the sample: 0.035 x 1.4 x 1021 = ?. ? ? ??????