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Title: Chemistry question helpppp Post by: cloveb on Oct 19, 2017 Determine the mass (in grams) of KCl required to prepare a 1.00 M solution in a 100 mL volumetric flask. What about a 2.00 M solution in 100 mL?
Title: Re: Chemistry question helpppp Post by: bolbol on Oct 19, 2017 You would need 7.45 g of KCl to make 100 mL of a 1.0 M solution.
M or molarity refers to the moles per litre of a solution. The first step is to calculate how many moles are in 100 mL of this solution. The easiest way is to use simple ratios. 1.0 mol / 1L = X mol / 0.1 L (100 mL has been converted to 0.1 L) To solve, cross multiply. X mol = 0.1L × 1.0 mol/1 L = 0.1 mol Therefore, there is 0.1 mol of KCl in 100 mL of the solution. Next, you need to calculate the molar mass of KCl, which can be done by adding the individual molar masses of K and Cl (found in most periodic tables of the elements). K= 39.01 g/mol Cl = 35.45 g/mol KCl= 74.46 g/mol Lastly, combine the two prior steps. If there is 74.46 g/mol of KCl per mole, and 0.1 mol of KCl in 100 mL of the solution, multiply the quantities. 0.1 mol × 74.46 g/mol = 7.446 g For 2.00 M solution in 100 mL, you would need 14.89 g of KCl Title: Re: Chemistry question helpppp Post by: bolbol on Dec 28, 2017 For more information on this subject, check out our Resource Library:
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