Multiple Choice
For a solution that is 0.164 M NH3 and 0.110 M NH4Cl, what is the concentration of Cl- ions?
6. Chemical Quantities & Aqueous Reactions
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You wish to prepare 194 grams of a 9.01% MgCl2 solution. How many grams of magnesium chloride (MgCl2) and how many mL of water will you need? Assume that the density of water is 1.00 g/mL.
A
9.01 grams of MgCl2 and 184.99 mL of water
B
20.00 grams of MgCl2 and 174.00 mL of water
C
17.48 grams of MgCl2 and 176.52 mL of water
D
19.40 grams of MgCl2 and 174.60 mL of water
Verified step by step guidance1
Start by understanding the concept of a percentage solution. A 9.01% MgCl2 solution means that 9.01 grams of MgCl2 are present in every 100 grams of the solution.
Calculate the mass of MgCl2 needed for the entire solution. Use the formula: \( \text{mass of MgCl2} = \frac{\text{percentage of MgCl2}}{100} \times \text{total mass of solution} \). Substitute the values: \( \text{mass of MgCl2} = \frac{9.01}{100} \times 194 \).
Determine the mass of water required. Subtract the mass of MgCl2 from the total mass of the solution: \( \text{mass of water} = \text{total mass of solution} - \text{mass of MgCl2} \).
Convert the mass of water to volume using the density of water. Since the density of water is 1.00 g/mL, the volume in mL is equal to the mass in grams: \( \text{volume of water} = \text{mass of water} \).
Verify your calculations to ensure the total mass of the solution is 194 grams and the percentage of MgCl2 is 9.01%.
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