You found a bottle of aqueous solution in the laboratory cabinet. Unfortunately, the label has been eroded and you could not recognize it. To the best of your recollection, it may be one of the following solutions: HCl CH3COOH CH3CH2COOH A mixture of HF and NaF (both of substantial amount) A mixture of H3PO4 and NaH2PO4 (both of substantial amount) NH4Cl NaHCO3 In order to identify the solution, you conduct the following experiments: Using a pH meter, you determine the pH of the solution to be 3.00. You dilute 20 mL of the solution with water to a total volume of 200 mL and measure the pH again, this time it reads 3.50. You take some volume of the solution, add phenolphthalein, and titrate it with NaOH solution until the mixture turns pink. You record the volume of the required titrant as Vt and the pH meter reads 9.05. In a separate flask, you take the same volume of the unknown solution as in step iii and titrate it with the same NaOH solution, but this time only add half of the volume Vt/2. The mixture remains colorless and the pH meter reads 4.87. The volume of the unknown solution you took in steps iii and iv was 20.00 mL. The concentration of the NaOH solution was 0.04587 M and Vt = 32.98 mL. Calculate the concentration(s) of the unknown species.
Ionic Equilibrium
Chemical equilibrium and ionic equilibrium are two major concepts in chemistry. Ionic equilibrium deals with the equilibrium involved in an ionization process while chemical equilibrium deals with the equilibrium during a chemical change. Ionic equilibrium is established between the ions and unionized species in a system. Understanding the concept of ionic equilibrium is very important to answer the questions related to certain chemical reactions in chemistry.
Arrhenius Acid
Arrhenius acid act as a good electrolyte as it dissociates to its respective ions in the aqueous solutions. Keeping it similar to the general acid properties, Arrhenius acid also neutralizes bases and turns litmus paper into red.
Bronsted Lowry Base In Inorganic Chemistry
Bronsted-Lowry base in inorganic chemistry is any chemical substance that can accept a proton from the other chemical substance it is reacting with.
You found a bottle of aqueous solution in the laboratory cabinet. Unfortunately, the label has been eroded and you could not recognize it. To the best of your recollection, it may be one of the following solutions:
-
HCl
-
CH3COOH
-
CH3CH2COOH
-
A mixture of HF and NaF (both of substantial amount)
-
A mixture of H3PO4 and NaH2PO4 (both of substantial amount)
-
NH4Cl
-
NaHCO3
In order to identify the solution, you conduct the following experiments:
-
Using a pH meter, you determine the pH of the solution to be 3.00.
-
You dilute 20 mL of the solution with water to a total volume of 200 mL and
measure the pH again, this time it reads 3.50.
-
You take some volume of the solution, add phenolphthalein, and titrate it with
NaOH solution until the mixture turns pink. You record the volume of the required titrant as Vt and the pH meter reads 9.05.
-
In a separate flask, you take the same volume of the unknown solution as in step iii and titrate it with the same NaOH solution, but this time only add half of the volume Vt/2. The mixture remains colorless and the pH meter reads 4.87.
The volume of the unknown solution you took in steps iii and iv was 20.00 mL. The concentration of the NaOH solution was 0.04587 M and Vt = 32.98 mL. Calculate the concentration(s) of the unknown species.
-
i) The pH of the solution is 3.00, that means it is an acidic solution. This rules out the solution to be NaHCO3, which is a alkaline.
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