Considering the definition of percentage by mass, the %mass/mass of a methanol solution prepared by mixing 70 grams of ethanol and 800 grams of water is 8.05 %.
The percentage by mass expresses the concentration and indicates the amount of mass of solute present in 100 grams of solution.
In other words, the percentage by mass of a component of the solution is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.
The percentage by mass is calculated as the mass of the solute divided by the mass of the solution, the result of which is multiplied by 100 to give a percentage. This is:
[tex]percentage by mass= \frac{mass of solute}{mass of solution}x100 [/tex]
In this case, you know:
Replacing in the definition of percentage by mass:
[tex]percentage by mass= \frac{70 g}{870 g}x100 [/tex]
Solving:
percent by mass= 8.05 %
Finally, the %mass/mass of a methanol solution prepared by mixing 70 grams of ethanol and 800 grams of water is 8.05 %.
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