Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: sarahjane on March 22, 2004, 04:21:42 AM
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how do you calculate the amount of potassium dichromate required to make 250mLs of a 0.15M solution
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Simply enough, molarity is just the measure of the number of moles of a solute in liters of a solvent. So molarity (M) is equal to the number of moles of solute divided by the liters of solvent. M=n/V where n are moles of solute and V is the number of liters of solvent. There are three variables here. The problem has given you two of the variables, so you can solve it. 0.15M=n/0.250L so n = 0.0375moles of K2Cr2O7.
I'm probably sure they'll want you to convert it into grams so just multiply it by the molar mass.