Mixing Solutions

# Mixing Solutions

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## Mixing Solutions

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1. Mixing Solutions That have something in common.

2. Calculate the final concentration if 1.00 L of 2.00 M CaBr2 and 3.00 L of 1.50 M CaBr2 are mixed. • To find the final concentration(Molarity), we need total moles and total volume (litres). • 2.00M = moles 1.50M = moles • 1.00L 3.00L • moles = 2.00mol moles = 4.50mol • CaBr2 CaBr2

3. Total moles = 2.00mol + 4.50 mol = 6.50 mol • Total volume = 1.00L + 3.00L = 4.00L • New Molarity = 6.50 mol • 4.00 L • = 1.63 M

4. What if the solutions don’t contain the same solute?

5. What is the [Na+] when 250.ml of 1.00M NaCl is added to 400.ml of 1.00M Na2SO4? • NaCl  Na+ + Cl- • 1.00M 1.00M 1.00M • M = moles • litres • 1.00 = moles • 0.250 • moles = 0.250 mol NaCl • & the same for Na+ & Cl- Na2SO4  2Na+ + SO4-2 1.00M 2.00M 1.00M 1.00 = moles 0.400 moles = 0.400 mol Na2SO4 Therefore, 0.800 mol Na+ and 0.400 mol SO4-2

6. Since the 2 solutions contain Na+, we find the total moles of Na+ and the total volume of solution, then calculate the new molarity of the Na+ • NaCl  Na+ + Cl- • 0.250 mol • Na2SO4  2Na+ + SO4-2 • 0.800 mol • 0.250 mol + 0.800 mol = 1.050 mol Na+

7. Total volume = • 0.250 L + 0.400 L = 0.650 L • Molarity of the Na+ : • M = moles • litres • M = 1.050 = 1.62 M Na+ • 0.650

8. 500.cm3 of 2.0M MgCl2 is mixed with 300.cm3 of 3.8M Mg(OH)2 What is the [Mg+2]? • MgCl2 Mg+2 + 2Cl -1 • 2.0M 2.0M 4.0M • 2.0M = moles • 0.500L • Moles = 1.0 mol Mg+2 Mg(OH)2  Mg+2+2OH-1 3.8M 3.8M 7.6M 3.8M = moles 0.300L moles = 1.14 mol Mg+2

9. Total moles Mg+2= 1.0 mol + 1.14 mol • = 2.14 mol • Total volume = 0.500L + 0.300L • = 0.800L • Total molarity = 2.14 mol • 0.800L • = 2.68 M Mg+2

10. Calculate the concentration of all ions in solution for the following: • 2.30L of 4.50M Calcium Phosphate combined with 0.850L of 2.30M Calcium Nitride. • 1.80L of 2.10M Beryllium Sulfide combined with 0.900L of 3.00M Aluminum Sulfide.