Why do you boil the solution before titrating it?

Why do you boil the solution before titrating it?

Boiling for about a minute will expel carbon dioxide gas from the solution and raise the pH sufficiently to cause the color to change back to blue. As you approach the final end point, continue to compare the color of the solution being titrated with the color of the blank.

What is the purpose of boiling the water used to make the NaOH solution?

To prepare the sodium hydroxide solution a liter of distilled water was boiled for 10 minutes and cooled to remove the carbon dioxide. That step is necessary because Sodium hydroxide and carbon dioxide react in a solution to form an unwanted carbonate ion.

Why is it necessary to heat the solution after the addition of NaOH to the crushed aspirin?

This involves reacting the aspirin solution with a measured amount of sodium hydroxide; an amount that will exceed the amount of aspirin present. Because the hydrolysis reaction occurs at a very low rate at room temperature it will be heated to increase the reaction rate.

What is the purpose of back titration?

A back titration is used when the molar concentration of an excess reactant is known, but the need exists to determine the strength or concentration of an analyte. Back titration is typically applied in acid-base titrations: When the acid or (more commonly) base is an insoluble salt (e.g., calcium carbonate)

What is end point in titration?

end point: the point during a titration when an indicator shows that the amount of reactant necessary for a complete reaction has been added to a solution.

Why do you think the water needs to be distilled or boiled and cooled?

Distilled water is water that has been boiled to become steam and then cooled to become water again. It’s then free of minerals and salts. Distilled water is used in car batteries and in steam irons. Distilled water prevents the iron from getting clogged up inside from minerals.

Why was the solution of sodium hydroxide titrated first?

Solid NaOH is highly hygroscopic (it absorbs water from the air) and thus it cannot be accurately weighed. A KHP sample of known mass (and, therefore, known moles) can be titrated with the NaOH solution to determine very precisely the concentration of the NaOH. This procedure is called standardizing the NaOH solution.

Why is HCl used in back titration?

Aspirin is a weak acid that also undergoes slow hydrolysis; i.e., each aspirin molecule reacts with two hydroxide ions. To overcome this problem, a known excess amount of base is added to the sample solution and an HCl titration is carried out to determine the amount of unreacted base.

What is the difference between back and blank titration?

What Is the Difference Between a Direct Titration and a Back Titration? In a direct titration, a known excess of reagent that reacts with the analyte is used. In a direct titration, titrants react directly with the analyte. In a back titration, a known excess of reagent that reacts with the analyte is used.

Why is back titration used to determine calcium carbonate?

Calcium Carbonate is not soluble in water. This meant that analysing the carbonate content of eggshells required a back titration. This technique is used when the primary standard is not soluble in water and therefore a direct titration is not suitable.

What is the difference between titration and back titration?

The key difference between titration and back titration is that in a titration, we usually add a chemically equal amount of standard solution to the analyte whereas, in a back titration, we add an excess amount of standard solution to the analyte.

Where is the endpoint of a titration?

The point in the titration process which is indicated by color change of the indicator is called endpoint. It is the point where the analyte has completely reacted with the titrant.

Why do you boil the solution after titration?

There is no reason to boil the solution after the titration. After the titration, you are done, it doesn’t make any sense to boil the solution. But it does make sense to boil the solution during the titration: Why during titration of HCL and Na2CO3 the solution is boiled just before reaching the second equivalence point?

What is the result of a back titration?

The second titration’s result shows how much of the excess reagent was used in the first titration, thus allowing the original analyte’s concentration to be calculated. A back titration may also be called an indirect titration.

Why is it important to titrate HCl with NaOH?

You will react an accurately known amount of your mixture / impure CaCO3 with an accurately known excess of HCl. You will titrate the remaining HCl with NaOH to determine the amount of HCl left. The difference between the amount used and the amount remaining tells you how much HCl reacted with the CaCO3.