Expressing concentrations as a percent

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SUMMARY

The concentration of O2 in seawater is measured at 5.0 mg O2/L H2O, which translates to 0.01% when expressed as a percentage. The Earth's atmosphere contains 21% O2, indicating that it holds significantly more oxygen than seawater. The calculation involves converting milligrams to grams and using the atomic mass of O2, which is 32.00 g/mol, for accurate percentage determination. The discussion highlights the importance of correct unit conversion and understanding atomic mass in concentration calculations.

PREREQUISITES
  • Understanding of concentration calculations
  • Knowledge of unit conversions (mg to g)
  • Familiarity with atomic mass concepts
  • Basic chemistry principles regarding gases and liquids
NEXT STEPS
  • Research methods for calculating concentration percentages in solutions
  • Learn about the significance of atomic mass in chemical calculations
  • Explore the differences in gas concentrations in various environments
  • Study the principles of gas solubility in liquids
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Chemistry students, environmental scientists, and anyone interested in understanding gas concentrations in different mediums.

Illyaria
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Please post this type of questions in HW section using the template and showing your work.
You measure the concentration of O2 in seawater to be 5.0 mg O2/L H2O. Express this concentration as a percent.

Question 2: The Earth's atmosphere contains 21% O2/L of air. How much more oxygen does the atmosphere hold than seawater from the previous question?

So for question one I got 0.01% which I think is way off. For question 2, I was just going to subtract 21% from the answer from 1. I changed the milligrams to grams for question one.
 
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What was your attempt to solve #1?
 
Comeback City said:
What was your attempt to solve #1?

I converted the 1 5.0 mg to grams and got 0.005g. Then, I divided that by 50 which is the atomic msss for O2/L H2O I think and multiplied that by 100.
 
Atomic mass of Oxygen is 16.00 amu, so O2 would be 32.00. Why did you divide by it though and then multiply by 100?
 

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