Multiple Choice
What is the concentration of K⁺ ions in a 0.15 M solution of K₂S?
6. Chemical Quantities & Aqueous Reactions
Molarity
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What is the molarity of Br⁻ ions in a solution that is 0.200 M KBr?
A
0.100 M
B
0.050 M
C
0.200 M
D
0.400 M
Verified step by step guidance1
Understand that molarity (M) is defined as the number of moles of solute per liter of solution. In this problem, we are given the molarity of KBr, which is 0.200 M.
Recognize that KBr is a strong electrolyte and dissociates completely in water into K⁺ and Br⁻ ions. The dissociation can be represented by the equation: KBr → K⁺ + Br⁻.
Since each formula unit of KBr produces one Br⁻ ion upon dissociation, the concentration of Br⁻ ions in the solution will be the same as the concentration of KBr.
Therefore, the molarity of Br⁻ ions is equal to the molarity of the KBr solution, which is 0.200 M.
Conclude that the molarity of Br⁻ ions in the solution is 0.200 M, as each KBr unit contributes one Br⁻ ion to the solution.
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