Dilution Calculations

**Dilution Calculations** **Name:** 1. If 20.0 mL of 0.75 M HBr is diluted to a total volume of 90.0 mL, what is the molar concentration of the HBr in the resulting solution?   Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = (0.75 * 20) / 90 Cdil = 0.17 M 2. What is the molar concentration of the KOH solution resulting from mixing 55 mL of 0.15 M KOH and 75 mL of 0.25 M KOH? Answer: Cdil = (Cconc1 * Vconc1 + Cconc2 * Vconc2) / Vdil Cdil = ((0.15 * 55) + (0.25 * 75)) / (55 + 75) Cdil = 0.21 M 3. If 1 drop (0.050 mL) of 0.20 M NaBr is added to 100.0 mL of water, what is the molarity of the NaBr in the resulting solution? Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = (0.20 * 0.050) / (100.0 + 0.050) Cdil = 1.0 x 10^-4 M 4. What is the molar concentration of the HNO3 solution resulting from mixing 5.0 mL of 3.5 M HNO3 and 95 mL of 0.20 M HNO3? Answer: Cdil = (Cconc1 * Vconc1 + Cconc2 * Vconc2) / Vdil Cdil = ((3.5 * 0.005) + (0.20 * 0.095)) / (0.095 + 0.005) Cdil = 0.37 M 5. Concentrated HNO3 is 15.4 M. How would you prepare 2.50 L of 0.375 M HNO3 with water to make 2.5 L? Answer: Vconc = (Cdil * Vdil) / Cconc Vconc = (0.375 * 2.50) / 15.4 Vconc = 0.0609 L Mix 60.9 mL with water to make 2.5 L. 6. Concentrated H3PO4 is 14.6 M. How would you prepare 45.0 L of 0.0600 M H3PO4 with water to make 45.0 L? Answer: Vconc = (Cdil * Vdil) / Cconc Vconc = (0.0600 * 45.0) / 14.6 Vconc = 0.185 L Mix 185 mL with water to make 45.0 L. 7. If 300.0 mL of solution A contains 25.0 g of KCl and 250.0 mL of solution B contains 60.0 g of KCl, what is the molarity of the KCl in the solution resulting from mixing solutions A and   B? Answer: 25.0 g KCl * (1 mol KCl / 74.55 g KCl) = 0.335 mol 60.0 g KCl * (1 mol KCl / 74.55 g KCl) = 0.805 mol (0.335 mol + 0.805 mol) / (0.300 L + 0.250 L) = 2.07 M KCl 8. If 500.0 mL of 0.750 M NaCl is boiled down until the final volume is reduced to 300.0 mL, what is the final molarity of the NaCl (assume no salt is lost)?   Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = (0.750 * 500) / 300 Cdil = 1.25 M 9. How would you prepare 250.0 mL of 0.350 M HCl, starting with 6.00 M HCl? Answer: Vconc = (Cdil * Vdil) / Cconc Vconc = (0.350 * 250) / 6.00 Vconc = 0.0146 L Mix 14.6 mL with water to make 250.0 mL. 10. What mass of NaCl is needed to prepare 500.0 mL of 0.400 M NaCl? Answer: 0.500 L NaCl * (0.400 mol NaCl / 1 L) * (58.44 g NaCl / 1 mol NaCl) = 11.7 g NaCl 11. What is the concentration of the NaOH solution produced by mixing 125.0 mL of 0.250 M NaOH with 200.0 mL of 0.175 M NaOH?   Answer: Cdil = (Cconc1 * Vconc1 + Cconc2 * Vconc2) / Vdil Cdil = ((0.250 * 0.125) + (0.175 * 0.200)) / (0.325) Cdil = 0.204 M 12. What volume of 12.0 M NaOH is required in order to prepare 3.00 L of 0.750 M NaOH? Answer: Vconc = (Cdil * Vdil) / Cconc Vconc = (0.750 * 3.00) / 12.0 Vconc = 0.188 L 1) Add 50% of solution total as water to flask 2) Add 188 mL of base 3) Top up to 3.00 L flask mark 13. What is the concentration of CaCl2 produced when 55.0 mL of 0.300 M HCl is mixed with 80.0 mL of 0.550 M CaCl2? Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = (0.550 * 0.080) / (0.135) Cdil = 0.326 M 14. When 350.0 mL of 0.250 M MgCl2 is boiled down to a final volume of 275.0 mL, what is the molarity of the MgCl2 in the resulting solution? Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = (0.250 * 0.350) / (0.275) Cdil = 0.318 M 15. If 20.0 mL of 0.350 M NaCl and 75.0 mL of 0.875 M NaCl are mixed and the resulting solution is boiled down to a volume of 60.0 mL, what is the molarity of the NaCl in the final solution?   Answer: Cconc = (Cconc1 * Vconc1 + Cconc2 * Vconc2) / Vdil Cconc = ((0.350 * 0.020) + (0.875 * 0.075)) / (0.060) Cconc = 1.21 M 16. A solution is made by mixing 100.0 mL of 0.200 M BaCl2 and 150 mL of 0.400 M NaCl. What is the concentration of sodium chloride in the final solution? Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = ((0.400 * 0.150)) / (0.250) Cdil = 0.240 M 17. If 75.0 mL of 0.200 M Na3PO4 is added to 25.0 mL of 0.800 M K3PO4, what is the concentration of Na3PO4 in the mixture? Answer: Cdil = (Cconc * Vconc) / Vdil Cdil = ((0.200 * 0.075)) / (0.100) Cdil = 0.150 M