Question 169599
300 pounds of dissolved solids in 1000 gallons of sea water (given).
normal sea water contains about 3.5% solids (given).
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based on these facts, you can derive the approximate weight of sea water as follows:
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there are 300 pounds of solids in 1000 gallons of sea water.
this represent 3.5% of the total number of gallons of sea water.
300 pounds of solids is equivalent to 35 gallons of sea water.
this means that 35 gallons of sea water weighs 300 pounds.
300 pounds / 35 gallons = 8.571428571 pounds per gallon of sea water.
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the implicit assumption is that the solids are dissolved throughout the sea water so that the density of the sea water and the solids is the same throughout.
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i did a check on the web and found that the average weight of a gallon of sea water is in the neighborhood of this answer so i'm confident it's probably right.
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another way of looking at it would be:
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300 pounds of solids in 1000 gallons of sea water = .3 pounds of solids in 1 gallon of sea water.
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since solids are 3.5% of a gallon of sea water, then .3 pounds of solids represents 3.5% of the gallon.
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.3 pounds / .035 = 8.571428571 pounds for the full gallon.
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the assumption is again that the solids are diffused through the liquid so that the density of the solids and the liquids is the same throughout.
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best i can do.
not sure if i explained it well, but i think the answer is right.