A sample of 0.9537 g of KMnO4 was dissolved in water and made up to the volume i

Question

A sample of 0.9537 g of KMnO4 was dissolved in water and made up to the volume in a 500.0-mL volumetric flask. A 2.000-mL sample of this solution was transferred to a 1000-ml volumetric flask and dilluted to the mark with water. Next, 10.00 mL of the diluted solution was transferred to a 250.0-mL flask and diluted to the mark with water.

1.Calculate the concentration of the final solution (M). enter your answer in scientific notation.

2. Calculate the mass of KMnO4 needed to directly prepare the final solution.

Explanation / Answer

A sample of .8214g of KMnO4 was dissolved in water and made up to the volume in a 500mL volumetric flask. A 2mL sample of this solution was transferred to a 1000mL volumetric flask and diluted to the mark with water. Next, 10mL of the diluted solution were transferred to a 250mL volumetric flask and diluted to the mark with water. i. Calculate concentration (in molarity) of the final solution ii. Calculate the mass of KMnO4 needed to directly prepare the final solution Calculate the molar mass of KMnO4 and divide 0.8214 g by the molar mass to get moles of KMnO4 in that sample. Then, divide that number of moles by 0.500L to give you the molar concentration of the initial sample. Next use M1V1 = M2V2 where M1 is the molarity of the initial sample, V1 is 2 mL and V2 is 1000 mL to calculate the molarity of the second solution. Finally use the same equation to do the same calculation to get the final concentration, using 10 mL for V1 and 250 mL for V2. For the last question, multiply the final molarity by 0.250 L to give you the number of moles of KMnO4 in that final solution. Then, multiply that by the molar mass of KMnO4 to give you the mass in grams needed.

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