Lesson 7:
Acids and Bases
Reactions of hydrochloric
acid

Reactions of sulfuric
acid

HCl H^{+} + Cl^{}  H_{2}SO_{4
}
H^{+} + HSO_{4}^{} HSO_{4}^{ } H^{+} + SO_{4}^{2} 
When talking about the concentration of acids or bases, we use measurements which involve equivalents. An equivalent is the number of moles of hydrogen ions one mole of an acid will donate or one mole of a base will accept. For example, hydrochloric acid has an equivalent value of 1 because each molecule of acid donates only one hydrogen ion, so one mole of hydrochloric acid will donate one mole of hydrogen ions. Sulfuric acid, on the other hand, has an equivalent value of 2. To give you a couple more examples, sodium hydroxide has an equivalent value of 1 while calcium hydroxide has an equivalent value of 2.
Let's simplify equivalents here:
For instance, you have calcium hydroxide, Ca(OH)_{2}. You can see there are 2 oxygen ions and 2 hydrogen ions, therefore the equivalent is 2. Another instance, sulfuric acid which is listed above, H_{2}SO_{4}. You can see there are 2 Hydrogen ions and 4 Oxygen ions. Since you have to have equal amounts to remove the ions, this equivalent will be 2. If you had 3 Hydrogen ions and 4 Oxygen ions, the equivalent would be 3 because you had enough oxygen ions to take care of the 3 hydrogen ions. Sodium Hydroxide, NaOH, has an equivalent of 1 since there is 1 Oxygen ion and 1 Hydrogen ion. You have to be able to have one oxygen ion for every hydrogen ion you are trying to get rid of.
Normality
Normality is the most
common measurement used for showing the concentration of acids and bases.
Normality takes into account both the molarity of the solution and the equivalent
content of the acid or base, using the equation shown below:
Calculating Normality From Grams
To calculate the normality of a solution you are preparing,
you need to combine the equation for calculating molarity and the equation
for calculating normality. To simplify matters, we've combined the two
equations for you:
So what would the normality of the solution be if we dissolved 6.80 grams
of calcium hydroxide in water to produce a 0.50 L solution? First, we
have to calculate the molar mass of calcium hydroxide  74.10 g/mol.
Then we have to figure out the equivalent value of calcium hydroxide  2.
And, finally, we can just plug numbers into the equation:
Part 4: Alkalinity