Convert ppm to mg/L - Calculate Grams of A Needed

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Discussion Overview

The discussion revolves around a homework problem involving the conversion of concentration from ppm to mg/L and the calculation of the required mass of a substance (A) to achieve a specific concentration of its product (C) in water (B). The scope includes mathematical reasoning and conceptual clarification regarding the relationships between the quantities involved.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant states that they assumed ppm equals mg/L, leading to the conclusion that 0.5 ppm corresponds to 0.5 mg/L, resulting in a need for 100 mg of A for twenty liters of water.
  • Another participant agrees with the conclusion of needing 100 mg of A but expresses confusion regarding the wording of the question.
  • A further participant confirms that 100 mg was indeed the correct answer but seeks clarification on the source of confusion regarding the question's wording.
  • One participant raises a question about the mass of the product formed when 0.1 g of A reacts with water, suggesting that it seems counterintuitive that the mass of the product would also be 0.1 g.

Areas of Agreement / Disagreement

There is agreement among some participants that 100 mg of A is the correct answer. However, there is also confusion regarding the wording of the question and a separate inquiry about the mass of the product, indicating that not all aspects of the discussion are resolved.

Contextual Notes

The discussion highlights potential ambiguities in the problem's wording and the assumptions made regarding the relationships between the mass of A and the mass of the product C. There are unresolved questions about the implications of these relationships.

Cypher49
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Homework Statement


A is a stable powder
B is water
C is the product of the powder being in contact with water.

A is soluble in substance B and for every gram of A 10% is C.

For a concentration of 0.5ppm of C in twenty liters of water how many grams of A do you need?


The Attempt at a Solution


I went on the assumption that ppm=mg/l.
So 0.5ppm=0.5mg/l, and I would need 10mg for the twenty liters
Which means that I would need 100mg of A.

Is this correct?
 
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Cypher49 said:
I would need 100mg of A.

Is this correct?

That would be my answer as well, although I find the wording of the question confusing.
 
Thanks for the confirmation, I'm just replying to say that 100mg was indeed the correct answer.

If you don't mind me asking, how did the wording confuse you?
 
If 0.1g of A reacted with water, what is mass of the product? Again 0.1g? Not impossible, but counterintuitive, at least to me.
 

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