# Quantitative Titration of Unknown Solid Acid: Find Molar Mass & Formula

• jessica.so
In summary, this conversation discusses the possibility of finding the molar mass or formula of an unknown solid acid by dissolving it in water and titrating it with NaOH. The given information includes the mass of the acid, the volume of the acid solution, the volume of base used, and the concentration of NaOH. It is mentioned that the acid is monoprotic and a formula is suggested for calculating the acid dissociation constant to determine the molar mass. However, it is clarified that the Ka is not needed and the molar mass can be calculated using the neutralization stoichiometry.
jessica.so
If you were given a sample unknown solid acid that had a mass of 0.7 g and it was being dissolved in 50 mL of water and was being titrated with NaOH, is it possible to find the molar mass or the formula of the acid?

Given information
Mass of solid acid: 0.7 g
Volume of acid solution: 50 mL = 0.05 L
Volume of base used: 29.5 mL = 0.0295 L
[NaOH] = 0.095 mol/L

I was also told that this is monoprotic.
HX (aq) + NaOH (aq) --> H2O (l) + NaX (aq)

Hi,
I would try to get the Acid dissociation constant with this little formula:
Ka=( [A-]*[H+])/[HA]
How many H+ were in the solution?
How many mol are 0,7 g H+ ?= c (O)
HA = c0 H+ - [H+].
Then you just have to search for the specific the ka in and you have you acid.
Greetings Firelion

No need for acid dissociation constant, in fact it is completely unrelated to problem.

If acid is monoprotic you can easily calculate number of moles from the neutralization stoichiometry. Then you know mass of the sample and number of moles in the sample - that's enough to calculate molar mass.

--

oh sorry.
We leraned in our exams to calculate very different types of data with the Ka so I thought this task is similar.

## 1. What is the purpose of a quantitative titration of unknown solid acid?

The purpose of a quantitative titration of unknown solid acid is to determine the molar mass and formula of the acid by measuring the amount of a standardized base needed to neutralize a known amount of the acid.

## 2. How is the molar mass of the unknown solid acid calculated?

The molar mass of the unknown solid acid is calculated by using the formula M = (n x V x Mbase) / m, where M is the molar mass of the acid, n is the number of moles of acid used, V is the volume of base used, Mbase is the molar mass of the base, and m is the mass of the acid sample.

## 3. What is the importance of using a standardized base in the titration process?

The use of a standardized base is important because it ensures accuracy and precision in the titration process. A standardized base is a solution with a known concentration, allowing for precise measurements and calculations in determining the molar mass and formula of the unknown solid acid.

## 4. How does the indicator used in the titration process work?

The indicator used in the titration process changes color when the solution reaches the equivalence point, which is when the moles of acid and base are in a 1:1 ratio. This indicates that the titration is complete and helps determine the endpoint of the reaction.

## 5. Can the titration process be used to determine the formula of any acid?

Yes, the titration process can be used to determine the formula of any acid as long as the acid can be dissolved in a solvent and reacts with a base in a 1:1 ratio. However, the process may need to be adjusted for strong acids or weak acids with multiple ionizable protons.

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