1. Calculations Involving Molarity (Aqueous Solution)
If 100 mL of 1.00 M NaOH and 100 mL of M H2SO4 solution are mixed, what will the concentration of the resulting salt solution be?
1) Write the balanced equations:
2NaOH + H2SO4  Na2SO4 + 2H2O
2) Determine the starting # of moles of each reactant:
moles NaOH = 1.00 mol/L * 0.100L = mol NaOH
moles H2SO4 = mol/L * 0.100L = mol H2SO4
3) Determine the limiting reagant:
moles of Na2SO4 from NaOH =
0.100 mol NaOH*(1 mol Na2SO4/2mol NaOH)=0.0500mol Na2SO4
moles of Na2SO4 from H2SO4 =
mol H2SO4*(1 mol Na2SO4/1mol H2SO4)=0.0500mol Na2SO4
4) Determine the final molarity:
M of Na2SO4 = mol Na2SO4/(0.100L L)=0.250 M Na2SO4

2. If 100 mL of 1.00 M NaOH and 100 mL of M H2SO4 solution are mixed, what will the concentration of the resulting salt solution be?
2NaOH + H2SO4  Na2SO H2O
Rxn Ratio: mol mol mol mol
Start: mol mol mol
Change: mol mol mol
Determine the final molarity:
M of Na2SO4 = mol Na2SO4/(0.100L L)=0.250 M Na2SO4

3. mmoles (millimoles) mmoles = 10-3 moles & mL = 10-3 L
Molarity = mmol/mL = 10-3 mol/10-3 L = mol/L
If 100 mL of 1.00 M NaOH and 100 mL of M H2SO4 solution are mixed, what will the concentration of the resulting salt solution be?
2NaOH + H2SO4  Na2SO4 + 2H2O
mmoles NaOH = 1.00 mol/L * 100mL = 100 mmol NaOH
mmoles H2SO4 = mol/L * 100mL = 50.0 mmol H2SO4
mmoles of Na2SO4 from NaOH =
100 mmol NaOH*(1 mmol Na2SO4/2mmol NaOH)=50.0 mmol Na2SO4
mmoles of Na2SO4 from H2SO4 =
50.0mmol H2SO4*(1 mmol Na2SO4/1mmol H2SO4)=50.0 mmol Na2SO4
M of Na2SO4 = 50.0mmol Na2SO4/(100mL + 100mL)=0.250 M Na2SO4

4. Titrations
Titration - the process by which one determines the volume of a standard solution required to react with a specific amount of another substance.
Standard solutions - solutions of accurately known concentrations.
Primary Standard - a compound that exists in a known high degree of purity, doesn’t react with the atmosphere, is soluble in water, has a high formula weight and reacts according to one invariable reaction.
Secondary Standard - A solution that is standardized by a primary standard.
Standardization - a process by which one determines the concentration of a solution by titration with a standard solution.
Equivalence point - the point at which chemically equivalent amounts of acid and base have reacted (neutralization).
End point - the point at which the indicator changes color. (Slightly past the equivalence point)

5. Indicator - a highly colored substance that can exist in different forms, with differnet colors that depend on the concentration of protons in soln.

6. Acid-Base Titration
Common Primary Standard - Potassium Hydrogen Phthalate (KHP) an acidic salt.
phthalic acid
C6H4(COOH)2
C8H6O4
K C6H4(COO)(COOH)
KC8H5O4
KHP + NaOH  NaKP + H2O

7. Na2CO3 + H2SO4Na2SO4 + H2O + CO2
Sodium carbonate is another common primary standard
What is the molarity of a sulfuric acid solution if 40.0 mL of the solution neutralizes grams of sodium carbonate?
Na2CO3 + H2SO4Na2SO4 + H2O + CO2
? M of sulfuric acid = mol H2SO4/L of soln
We need to find the mol of H2SO4
0.364 g NaCO3*(1 mol/106.0g Na2CO3)*(1mol H2SO4/1mol Na2CO3)
= mol H2SO4
M H2SO4 = mol H2SO4/0.0400L H2SO4 = M H2SO4