Multiple Choice
What is the molarity of a solution prepared by dissolving 5.0 grams of NaCl (molar mass = 58.44 g/mol) in enough water to make 250 mL of solution?
6. Chemical Quantities & Aqueous Reactions
Molarity
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What volume in mL of 2.89 M Co(NO3)3 stock solution is needed to make 2.67 L of a solution with a nitrate ion concentration of 0.0148 M?
A
38.2 mL
B
67.8 mL
C
25.6 mL
D
52.4 mL
Verified step by step guidance1
Identify the relationship between the concentration of the stock solution and the desired solution. The stock solution is 2.89 M Co(NO3)3, which means it contains 3 moles of nitrate ions per mole of Co(NO3)3.
Calculate the concentration of nitrate ions in the stock solution. Since Co(NO3)3 dissociates into one Co^3+ ion and three NO3^- ions, the nitrate ion concentration in the stock solution is 3 times the concentration of Co(NO3)3, which is 3 * 2.89 M.
Determine the total moles of nitrate ions needed in the final solution. Use the formula: moles of nitrate ions = concentration of nitrate ions * volume of solution. Here, the concentration is 0.0148 M and the volume is 2.67 L.
Calculate the volume of the stock solution needed to provide the required moles of nitrate ions. Use the formula: volume of stock solution = moles of nitrate ions / concentration of nitrate ions in stock solution.
Convert the volume from liters to milliliters, as the final answer requires the volume in mL. Remember that 1 L = 1000 mL.
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