*Direct titration- is a way to determine the contents of a substance quantitatively. Scientists may be aware of a reactant, but not know the reactant's quantity. Direct titration is sometimes based on indicators that respond to the analyzed material, called the analyte. Other times, the methods are based on the use of added metal ions, which are individual atoms or molecules of a specific type of metal.

 

The key steps in the calculations of a direct titration are

1. The moles of titrant = Volume x Molarity

2. Using the stoichiometry of the balanced equation, relate the number of moles of the titrant to the number of moles of the analyte.

Direct titration with only 1 reaction:

 

 

 

 

 

 

 

 

 

Example 1:

• Potassium hydrogen phthate, KHC8H4O4  ( MM = 204.23), is a primary standard acid that reacts with sodium hydroxide on a 1.1 molar basis. Result showed that 0.5893 g of primary standard grade potassium hydroxide phthate required 22.49 ml to reach the phenolphthalein endpoint. Calculate the molar concentration of the NaOH solution.

• M=?

 

*Solution:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Example 2:

• 11.6 mL of 3.0 M sulfuric acid are required to neutralize the sodium hydroxide in 25.00 mL of NaOH solution. What is the molarity of the NaOH solution?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References: Chemistry Notes

 

 

Written By: Nina Manuel