Question

The information in this question will be used for questions 9 through 16 and mirror steps 3 - 10 in the calculation section of the manual. The concentration of Cr3+3+ ions in a 25.00 mL volumetric flask, after reaction a sample of diluted vodka with acidic potassium dichromate, was found to be 0.0192 M.

1.Calculate the moles of Cr3+3+ in the 25 mL volumetric flask.

2.Calculate the moles of ethanol that reacted with the acidic potassium dichromate to produce the Cr3+3+ ions .

3.Calculate the molarity of ethanol in the dilute vodka sample used in the analysis. As in the lab procedure, 2.50 mL of diluted vodka sample for the analysis.

4.Calculate the molarity of the ethanol in the undiluted vodka sample. As in the lab procedure, the original (undiluted) vodka was diluted 1/40

5.Calculate the mass of ethanol (CH33​CH22​OH) in a litre of vodka.

6.Given that the density of ethanol (CH33​CH22​OH) is 0.789 g⋅mL−1−1, convert the mass of ethanol into a volume of ethanol in a litre of vodka.

7.When 2 miscible liquids are mixed, very seldom does the final volume equal the combined volumes of the individual liquids. The 2 liquids solvate each other and the final volume is almost always less. This is called non-ideal behaviour. Since ethanol and water are infinitely miscible, vodka is an example of a non-ideal solution and the volume of ethanol is determined by multiplying by
976 mL/1000mL.
What is the corrected volume of ethanol in 1 liter of vodka?

8.Report the % ethanol (v/v) in the vodka sample.

% ethanol (v/v) = (volume of ethanol in mL / 1000 mL) x 100 %

Answer 1

As given the concentration of Cr3+ ions in 25 mL volumtric flask diluted with vodka and diluted potassium dichormate is = 0.0192 M

Conc = 0.0192 mol/Litre

Conc = no of moles/volume in Litre

25 mL = 0.025 Litre

0.0192 mol/Litre = no of moles/0.025L

No of moles = 0.0192 x 0.025 moles

no of moles = 0.00048 or 0.48 mili moles