미해결 질문
We prepare a solution by mixing 0.10 L of 0.12 M sodium chloride with 0.23 L of a 0.18 M MgCl2 solution. What volume of a 0.20 M silver nitrate solution is needed to precipitate all the Cl- ions in the solution as AgCl?
6. Chemical Quantities & Aqueous Reactions
Solution Stoichiometry
Multiple Choice
A student dissolved 5.00 g of Co(NO3)2 in enough water to make 100.0 mL of stock solution. He took 4.00 mL of the stock solution and then diluted it with water to give 275.0 mL of a final solution. How many grams of NO3- ion are there in the final solution?
A
0.018 g
B
0.036 g
C
0.073 g
D
0.146 g
검증된 단계별 안내1
First, calculate the molar mass of Co(NO3)2. Use the atomic masses: Co = 58.93 g/mol, N = 14.01 g/mol, O = 16.00 g/mol. The formula is Co(NO3)2, so the molar mass is calculated as: g/mol.
Determine the moles of Co(NO3)2 in the stock solution. Use the formula: moles.
Calculate the concentration of Co(NO3)2 in the stock solution. Use the formula: M (molarity).
Find the moles of Co(NO3)2 in the 4.00 mL of stock solution. Use the formula: moles.
Calculate the grams of NO3- ions in the final solution. Since each Co(NO3)2 molecule contains 2 NO3- ions, multiply the moles of Co(NO3)2 by 2 to get moles of NO3-. Then convert moles of NO3- to grams using the molar mass of NO3-: g/mol.
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