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  1. Which variable is the independent variable and which is the dependent variable? Density vs. ethylene glycol

AA 25-mL volumetric flask with its stopper has a mass of 32.6341 g. The same flask filled to the line with ethylene glycol (C2H6O2, automotive antifreeze) solution has a mass of 58.0091 g. What is the density of the ethylene glycol solution?

BWhat is the molarity of the ethylene glycol solution, if the mass of ethylene glycol in the solution is 12.0439 g?

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1. Which variable is the independent variable and which is the dependent variable? Density vs. ethylene glycol
The independent variable would be ethylene glycol and dependent variable would be density.

A. A 25-mL volumetric flask with its stopper has a mass of 32.6341 g. The same flask filled to the line with ethylene glycol (C2H6O2, automotive antifreeze) solution has a mass of 58.0091 g. What is the density of the ethylene glycol solution?

Density = 58.0091 - 32.6341 / .025 = 1015 g/L

B. What is the molarity of the ethylene glycol solution, if the mass of ethylene glycol in the solution is 12.0439 g?

Molarity = 12.0439 ( 1 mol / 62.07 g) / 0.025 = 7.8 M

Answer:

Density is independent variable and mass is dependent variable.

A. 1.015 g/mL is the density of the ethylene glycol solution.

B. 16.378 mol/L is the molarity of the ethylene glycol solution.

Explanation:

Independent variable is defined as the variable which remain as such and has no effect on the change of another variable. For

Dependent variable is defined as the variable whose value varies with respect to any other variable.

Density is an independent factor as one can determine it by the slope of graph of mass verses volume. Density will remain same on changing the mass of the substance.

Where as mass of ethylene glycol is dependent  variable.

A. Mass of volumetric flask with stopper = 32.6341 g

Mass of volumetric flask, stopper and ethylene glycol =  58.0091 g

Mass of ethylene glycol = 58.0091 g - 32.6341 g =25.3751 g

Volume of the volumetric flask = 25 mL

\(Density=\frac{Mass}{Volume}\)

Density of ethylene glycol = D

\(D=\frac{25.3751 g}{25 mL}=1.015 g/mL\)

B. \(Molarity=\frac{Moles}{Volume(L)}\)

Moles of ethylene glycol ,n = \(\frac{25.3751 g}{62 g/mol}=0.4093 mol\)

Volume of the solution = V = 25 mL = 0.025 L

Molarity =\(\frac{0.4093 mol}{0.025 mL}=16.37 mol/L\)

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