Wednesday, March 9, 2011

Diluting Solutions

- When two solutions are mixed, the concentration changes
- Dilution is the process of decreasing the concentration by adding a solvent (usually water)
- This amount of solute does not change

n1= n2

- Because the concentration is mol/L, we can write:
C = n/v  C = mol/v

and n (of mol) = CV
c1v1 = c2v2

Example: Determine the “C” when 100 ml of 0.10 M of HCl is diluted t a final volume of 400 ml
c1v1 = c2v
c2 = c1v1/v2= (0.1L)(0.1M)/(0.4L) = 0.025 mol/L

*Remember ‘[ ]’ means concentration

100 mL of 0.50 M Sodium Nitrate is mixed with 200mL of 100M Sodium Nitrate
- Determine the # of moles of Sodium Nitrate in the resulting solutions
n1 + n2 = (0.100L) x 250mol/ L + (0.200L) x 0.1 mol/L
             =  0.025 mol + 0.02 mol
             =  0.0450 mol
Determine the final NaNo3 --> (0.0450mol)/(0.300L) = 0.150 M

Jomar Delos Santos

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