Chemistry: Combined Acid-Base and Redox Titrations

In summary, to determine the acid concentration of a mixture of (COOH)2 and H2SO4, titrate it against NaOH with a concentration of 0.2M. The average titre figure of NaOH is 8.93cm3 and 10mL of the mixture is added. Using the reaction ratio of NaOH: (COOH)2:H+ ions, calculate the moles of H+ ions present in the mixture. Then, add the moles of H+ ions from NaOH and H2SO4 and express the total in mols/L to obtain the concentration of H+ ions, which in this case is 0.003786M.
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Homework Statement


Determine acid concentration of a mixture of (COOH)2 and H2SO4 by titration against NaOH
Concentration of NaOH = 0.2M
Average Titre Figure (NaOH) = 8.93cm3
Volume of mixture added = 10mL

Homework Equations


2NaOH + (COOH)2 [tex]\rightarrow[/tex] 2NaCOO + 2H2O


The Attempt at a Solution


Reaction ratio NaOH: (COOH)2:H+ions = 2:1:2
Molarity of NaOH 0.2M
Moles of NaOH in 8.93mL = 1.786 x 10-3 mol
Moles of H+ ions = 1.786 x 10-3 mol in 10mL

A similar calculation for H2SO4. Then do you just add the moles and express in mols/L?
 
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  • #2
Moles of H2SO4 in 10mL = 0.1 x 0.2 = 0.02 molTotal moles of H+ ions = 0.01786 + 0.02 = 0.03786 molConcentration of H+ ions in mols/L = 0.03786/10 = 0.003786M
 

1. What is the purpose of combined acid-base and redox titrations in chemistry?

Combined acid-base and redox titrations are used to determine the concentration of a specific substance in a solution. This can be helpful in various industries, such as pharmaceuticals and environmental testing, to ensure the quality and safety of products.

2. How do you perform a combined acid-base and redox titration?

First, a known volume of the solution to be analyzed is placed in a titration flask. Then, a titrant, which is a solution of a known concentration, is slowly added to the solution while monitoring the pH or potential change. The titration endpoint is reached when the pH or potential reaches a specific value, indicating that all of the substance being analyzed has reacted with the titrant. The amount of titrant used can then be used to calculate the concentration of the substance in the original solution.

3. What is the difference between an acid-base titration and a redox titration?

An acid-base titration involves the neutralization of an acid or base with a strong base or acid, respectively. This is determined by the change in pH of the solution. In a redox titration, a reducing agent is titrated with an oxidizing agent, or vice versa. The endpoint is determined by a change in potential rather than pH.

4. What are some common indicators used in combined acid-base and redox titrations?

In acid-base titrations, indicators such as phenolphthalein, methyl orange, and bromothymol blue can be used to determine the endpoint based on a change in color. For redox titrations, indicators such as potassium permanganate and potassium dichromate can be used to determine the endpoint based on a color change or the disappearance of a colored species.

5. What are some potential sources of error in combined acid-base and redox titrations?

Some potential sources of error in combined acid-base and redox titrations include inaccurate measurements of the volumes of solutions used, contamination of solutions, and incomplete reactions. It is important to carefully follow the procedures and use proper technique to minimize these errors.

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