Chemistry
mvinges
11

Larutan kcl dengan konsentrasi 0,5 m dapat dibuat dengan melarutkan serbuk kcl ke dalam 100 ml air. jika diketahui Mr KCL 74,5 massa kcl yang harus dilarutkan adalah

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(1) Answers
Kelly25toby

I think your question is: "A solution with a concentration of 0.5 m can be made by dissolving the solid in 100 mL of water. If the known [latex] M_{r} [/latex] of KCl is 74.5, the mass should be _____. Assume that the density of water is 1.00 g/mL. Then the mass of the water is 100 g. 0.5 m KCl = 0.5 mol KCl/kg water ∴ Moles of KCl = 100 g H₂O × [latex] \frac{0.5 mol KCl}{1000 g H_{2}O } [/latex] = 0.05 mol KCl Mass of KCl = 0.05 mol KCl × [latex] \frac{74.5 g KCl}{1 mol KCl} [/latex]= 3.725 g KCl Note: The answer can have only 1 significant figure, because that is all you gave for the molality of the solution. To the correct number of significant figures, the correct answer is 4 g KCl.

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