Exp 4b (Gen Chem) PRELAB-DUE AT THE BEGINNING OF LAB 1. A 25-mL volumetric flask

Question

Exp 4b (Gen Chem) PRELAB-DUE AT THE BEGINNING OF LAB 1. A 25-mL volumetric flask with its stopper has a mass of 32.6341 g. The same flask filled to the line with Name: ethylene glycol (CaH.O, automotive antifreeze) solution has a mass of 58.0091 g. What is the density of the ethylene glycol solution? 2. An ethylene glycol solution is prepared by diluting 10. ml of a 5.2 M solution to a final volume of 25 ml What is the molarity of the diluted solution? 3. Use the information from the graph below to determine the mass percent of an unknown solution of ethylene glycol if the unknown has a density of 1.009 g'ml. Density vs. Mass Percent of Ethylene Glycol Solutions 1.0250 0200 0150 Density I/ml) 1.0300 0050 1.0000 09950 000 S.00 10.00 15.00 20.00 Mass Percent (N 0.0013+0.9978 R 0 99918

Explanation / Answer

Answer :

1) mass of the ethylene glycol =58.0091 g

Volume of the flask = 25 mL = 25/1000=0.025L

Density of the ethylene glycol = mass/ volume

= 58.0091/0.025

= 2320.36g/L

2. Find the molarity of the diluted solution

Using the dilution formula,

C1V1 = C2V2

C1 = 5.2 M, V1 = 10 ml, C2 = ? , V2 = 25 ml

5.2 * 10 = C2 *25

C2= 5.2*10/25 = 2.08 M

3. Determine the mass percent of unknown solution

From the graph, y= 0.0013x + 0.9978

Given that , density of ethylene glycol is 1.009 g/mL.

1.009 = 0.0013x + 0.9978

1.009-0.9978 = 0.0013x

0.0112 = 0.0013x

X = 0.0112/0.0013 = 8.615

Mass percent of the unknown solution is 8.615 %

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