Your Turn For each of the following scenarios, indicate what the student (hopefu
ID: 143134 • Letter: Y
Question
Your Turn For each of the following scenarios, indicate what the student (hopefully not youl) did incorrectly and why it is incorrect. 1. A student uses a spatula to transfer more of a dry solute than she will need onto a balance. She removes the excess from the balance and returns it to the original container of dry solute. lcau A student wants to make 100 mL of an aqueous solution. She measures out the correct mass of dry solute with a balance, transfers it to a beaker, and adds 100 mL of distilled water to dissolve. 2. 3. A student wants to make 100 mL of a 1M KMnOs solution. He measures 15.8 g of KMn04 with a balance and transfers it to a beaker. Then, subtracts this value from 100 to calculate that he needs 84.2 mL of water. He measures 84.2 mL of water, adds it to the beaker, and dissolves the KMnO4.Explanation / Answer
2. While preparing a 100ml aqueous solution, one must keep one thing in mind that the volume of the solution should be 100 ml not that of the solvent or water, because the solute would change the volume of the solution if 100 ml solvent is straightway added in beaker. Therefore, the correct procedure would be to dissolve the solute in 50ml water and then to make up or adjust the volume upto 100 ml by adding more water. In this case, most likely the solution in total would have a volume a little higher than 100 ml.
3. One hundred ml of 1 molar solution is a solution in which 1 mole of a compound is dissolved in a total volume of 100 ml. Now, in this case the amount of solute is in grams, that is its mass; but not suggestive of its volume at all. Therefore, the correct procedure would still be to dissolve the said amount of solute in 50 ml water and then making up the volume upto 100 ml after the solute dissolves completely. In this case, most likely the solution in total would not have a volume of 100 ml but less than it.
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