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Thread: Dependent variable

  1. #1 Dependent variable 
    Forum Masters Degree thyristor's Avatar
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    Hi!
    In an experiment I'm designing I am going to measure the amount of oxygen released in a certain chemical reaction. To do this, I have an eudiometer placed upside down in a water basin. For a particular reason (unnessecary to discuss here) I will not measure the actual volume by taking the readings from the eudiometer, but I will measure the height of the gas column inside the eudiometer and thus calculate the volume. In the end I will calculate the amount of substance.

    What would you call the dependent variable in this experiment? I know it's naively defined as "what you measure", so would that be the height of the column, the volume of oxygen or the amount of substance. I guess it would be the height, since that is what I'm actually measuring, while the other two are obtained from calculations. But assuming the height is the dependent variable, what would you then call the other two?

    Thanks in advance!


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  3. #2  
    Forum Professor jrmonroe's Avatar
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    IMO, amount (mM, M, etc) would be the most scientific result, and you might need to use the ideal gas law to determine the amount from the volume, depth in water, temp, etc.


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  4. #3  
    Forum Masters Degree thyristor's Avatar
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    Ok, thanks!

    Yes, I knew about the necessity of using the ideal gas equation, but didn't bother to write it. But thanks anyway :-D
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  5. #4 Re: Dependent variable 
    . DrRocket's Avatar
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    Quote Originally Posted by thyristor
    What would you call the dependent variable in this experiment? I know it's naively defined as "what you measure", so would that be the height of the column, the volume of oxygen or the amount of substance. I guess it would be the height, since that is what I'm actually measuring, while the other two are obtained from calculations. But assuming the height is the dependent variable, what would you then call the other two?

    Thanks in advance!
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    It depends on the function that you are considering anyway.

    Height is dependent on the oxygen content of your compound.

    Oxygen content is dependent on the mass and composition of the compound.

    The volume of oxygen is dependent on height of the gas column (and diameter, and temperature).


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  6. #5 Re: Dependent variable 
    Forum Masters Degree thyristor's Avatar
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by thyristor
    What would you call the dependent variable in this experiment? I know it's naively defined as "what you measure", so would that be the height of the column, the volume of oxygen or the amount of substance. I guess it would be the height, since that is what I'm actually measuring, while the other two are obtained from calculations. But assuming the height is the dependent variable, what would you then call the other two?

    Thanks in advance!
    Labels are not important.

    It depends on the function that you are considering anyway.

    Height is dependent on the oxygen content of your compound.

    Oxygen content is dependent on the mass and composition of the compound.

    The volume of oxygen is dependent on height of the gas column (and diameter, and temperature).


    "You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts. I learned very early the difference between knowing the name of something and knowing something." Richard P. Feynman
    Thanks for your reply!
    Always nice with a Feynman quote
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