Which equation is used to calculate the final concentration after diluting a solution?

• A. M_1 V_1 = M_2 V_2
• B. M_1 V_2 = M_2 V_1
• C. C_1 + C_2 = C_f
• D. V_1 / V_2 = M_2 / M_1

Answer: (A)

Verified step by step guidance

1. Understand that dilution involves adding solvent to a solution, which decreases the concentration but does not change the amount of solute.
2. Recall that the number of moles of solute before dilution equals the number of moles after dilution, since no solute is added or removed.
3. Express the moles of solute before dilution as \(n_1 = M_1 \times V_1\), where \(M_1\) is the initial molarity and \(V_1\) is the initial volume.
4. Express the moles of solute after dilution as \(n_2 = M_2 \times V_2\), where \(M_2\) is the final molarity and \(V_2\) is the final volume.
5. Set the moles before and after dilution equal to each other: \(M_1 \times V_1 = M_2 \times V_2\), which is the equation used to calculate the final concentration after dilution.