text: # Given percent composition, find mass per litre of solution
  
  1. May 15, 2016
  
  ### brbrett
  
  1. The problem statement, all variables and given/known data
  A 15% by mass solution has a density of 1.2 g/mL. What is the mass per liter concentration of this solution?
  → (a) 180 g/L (this is the answer, pretend you don't know)
  (b) 150 g/L
  (c) 125 g/L
  (d) cannot be determined from this information
  2. Relevant equations
  Density
  Possibly percent composition
  3. The attempt at a solution
  I don't know g/L.
  D=m/v
  I assume 15% of the solution is 15g (This is clearly not the case, or I wouldn't be here)
  1.2=15/v
  v=12.5mL
  Convert mL to L
  15g/0.0125mL
  1200g/L <---Not even on the answer list, and sounds unreasonable anyway
  
  Without straight telling me the answer, how does one approach a question such as this?
  
  2. May 15, 2016
  
  It's not the best problem in my opinion because the solution has a mass of 1200 g per liter, and if you subtract out the material that was dissolved, you have presumably what is water (when you are given a solution and the material is unspecified, water is usually implied), that must have a density that is at least 1020 grams per liter, and the volume might even be slightly less than a liter. (Sometimes the dissolved material will add volume. When it is removed, the volume could decrease.) 15% by mass of 1200 grams is 180 grams. I guess it is also fair to assume that the solution is not a water solution. Anyway, to help you with your calculations, there are 1000 ml (milliliters) in a liter. To do a percentage, you divide by 100. e.g. for 15%, its fractional value is 15/100=0.15.
  
  Last edited: May 15, 2016
  3. May 15, 2016
  
  ### SteamKing
  
  Staff Emeritus
  The problem statement clearly says the density of the solution is 1.2 g/mL. Don't you know that 1000 mL = 1 L?
  This is the mass per liter of solution. It is not the mass concentration, however.
  X% mass concentration of a solution means that:
  
  the mass concentration per liter = the mass of 1 liter of solution * X / 100
  
  4. May 15, 2016
  
  ### brbrett
  
  Now that I think about it, my work above was kinda silly :p
  Plugging into the equation, I get 180g/L from 1200x(15/100), which is the correct answer (which is just 15% of that number).
  What is mass concentration exactly? Is it simply the the part of the solution we are looking at, which implies the rest of the solution is water/other substances?
  
  5. May 15, 2016
  
  ### SteamKing
  
  Staff Emeritus
  Mass concentration is the amount of a substance dissolved in some sort of solute to make a solution. The solute can be water or any other liquid.
  
  Concentration can be defined in several different ways:
  
  https://en.wikipedia.org/wiki/Concentration
  
  6. May 15, 2016
  
  ### Staff: Mentor
  
  The mass concentration they are looking for is the mass of solute per liter of solution.
  
  7. May 15, 2016
  
  ### brbrett
  
  Got it. Unfortunately I only get to use Molarity in my current year of chemistry, so it's good that I now know what mass concentration is. Thanks for the help!
explanation: The document is a forum post discussing a chemistry problem that involves calculating the mass per liter concentration of a solution given its percent composition and density. The post includes a question and an attempt at a solution, followed by responses from other users providing guidance and explanations. The original poster eventually arrives at the correct answer with the help of the other users.
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  Output rules:
  
  1. Briefly describe the document and mention if it contains a question or a question and answer.
  2. Finalize the output with: Label: no-question,question,question-and-answer,multiple-question,multiple-question-and-answer
distilabel_metadata.role: system
distilabel_metadata.content: # Given percent composition, find mass per litre of solution
  
  1. May 15, 2016
  
  ### brbrett
  
  1. The problem statement, all variables and given/known data
  A 15% by mass solution has a density of 1.2 g/mL. What is the mass per liter concentration of this solution?
  → (a) 180 g/L (this is the answer, pretend you don't know)
  (b) 150 g/L
  (c) 125 g/L
  (d) cannot be determined from this information
  2. Relevant equations
  Density
  Possibly percent composition
  3. The attempt at a solution
  I don't know g/L.
  D=m/v
  I assume 15% of the solution is 15g (This is clearly not the case, or I wouldn't be here)
  1.2=15/v
  v=12.5mL
  Convert mL to L
  15g/0.0125mL
  1200g/L <---Not even on the answer list, and sounds unreasonable anyway
  
  Without straight telling me the answer, how does one approach a question such as this?
  
  2. May 15, 2016
  
  It's not the best problem in my opinion because the solution has a mass of 1200 g per liter, and if you subtract out the material that was dissolved, you have presumably what is water (when you are given a solution and the material is unspecified, water is usually implied), that must have a density that is at least 1020 grams per liter, and the volume might even be slightly less than a liter. (Sometimes the dissolved material will add volume. When it is removed, the volume could decrease.) 15% by mass of 1200 grams is 180 grams. I guess it is also fair to assume that the solution is not a water solution. Anyway, to help you with your calculations, there are 1000 ml (milliliters) in a liter. To do a percentage, you divide by 100. e.g. for 15%, its fractional value is 15/100=0.15.
  
  Last edited: May 15, 2016
  3. May 15, 2016
  
  ### SteamKing
  
  Staff Emeritus
  The problem statement clearly says the density of the solution is 1.2 g/mL. Don't you know that 1000 mL = 1 L?
  This is the mass per liter of solution. It is not the mass concentration, however.
  X% mass concentration of a solution means that:
  
  the mass concentration per liter = the mass of 1 liter of solution * X / 100
  
  4. May 15, 2016
  
  ### brbrett
  
  Now that I think about it, my work above was kinda silly :p
  Plugging into the equation, I get 180g/L from 1200x(15/100), which is the correct answer (which is just 15% of that number).
  What is mass concentration exactly? Is it simply the the part of the solution we are looking at, which implies the rest of the solution is water/other substances?
  
  5. May 15, 2016
  
  ### SteamKing
  
  Staff Emeritus
  Mass concentration is the amount of a substance dissolved in some sort of solute to make a solution. The solute can be water or any other liquid.
  
  Concentration can be defined in several different ways:
  
  https://en.wikipedia.org/wiki/Concentration
  
  6. May 15, 2016
  
  ### Staff: Mentor
  
  The mass concentration they are looking for is the mass of solute per liter of solution.
  
  7. May 15, 2016
  
  ### brbrett
  
  Got it. Unfortunately I only get to use Molarity in my current year of chemistry, so it's good that I now know what mass concentration is. Thanks for the help!
distilabel_metadata.role: user
distilabel_metadata.raw_output_q_a_detector_0: The document is a forum post discussing a chemistry problem that involves calculating the mass per liter concentration of a solution given its percent composition and density. The post includes a question and an attempt at a solution, followed by responses from other users providing guidance and explanations. The original poster eventually arrives at the correct answer with the help of the other users.
  
  Label: question-and-answer