Need some help with Acid base titrations

In summary, the ratio of [ln-]/[H ln] initially was 1 and after the addition of acid it will be 10000, the concentration of the base is 0.07 mol/L, and the moles of HCl theoretically neutralized is 7.37 x 10^-3 mol.
  • #1
babbagee
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I have several questions.

1.)Supose [H+] is 100 times less than the ka for an acidic acid-base indicator (see Eq.2), and enough acid is added to the the solution to raise [H+] by a factor of 10,000. What value did the ration of the different colored forms of the indicator, [ln-]/[H ln], have originally, and what value does it have after the addition of the acid?

Eq 2. ka= ([H+][ln-])/([Hln]) Kb= ([lnd+][OH-])/([lndOH])

2.)Potassium acid phthalate has a single hydrogen ion and a molar mass of 204.23 g/mol. Suppose you weigh out .500g of KHP and titrate it with a sodium hydroxide solution of unknown concentration. If it takes 35.0ml of the base to reach the end point, what is the concentration of the base?

3.) if a table contains 110 mg of Mg(OH)2 and 550mg CaCO3 how many moles of HCL would theoretically be neutralized.
*for this one do i just convert the mass into the mols of HCL and add them up.

Thanks
 
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  • #2
!1.) Initially, the ratio of [ln-]/[H ln] was 1. After the addition of acid, the ratio of [ln-]/[H ln] will be 10000.2.) Using the molar mass of KHP and the amount of base used, the concentration of the sodium hydroxide solution can be calculated as follows: 0.500 g / 204.23 g/mol = 0.002450 mol. Then, 0.002450 mol / 0.035 L = 0.07 mol/L. Therefore, the concentration of the base is 0.07 mol/L.3.) Yes, you can convert the mass of Mg(OH)2 and CaCO3 into moles of HCl and add them up. The equation for the reaction is 2HCl + Mg(OH)2 → MgCl2 + 2H2O and HCl + CaCO3 → CaCl2 + H2O. You would first convert 110 mg of Mg(OH)2 to moles of HCl (110 mg / 58.32 g/mol = 1.88 x 10^-3 mol HCl) and 550 mg of CaCO3 to moles of HCl (550 mg / 100.09 g/mol = 5.49 x 10^-3 mol HCl). Adding these two gives a total of 7.37 x 10^-3 mol HCl theoretically neutralized.
 
  • #3
for reaching out for help with acid-base titrations. Titrations can be a tricky topic, but I will do my best to answer your questions.

1. In order to answer this question, we need to use the Henderson-Hasselbalch equation, which relates the ratio of the different forms of an acid-base indicator to the pH of the solution. The Henderson-Hasselbalch equation is pKa = pH + log([A-]/[HA]), where pKa is the negative logarithm of the acid dissociation constant, [A-] is the concentration of the deprotonated form of the indicator, and [HA] is the concentration of the protonated form of the indicator. In this case, we are told that [H+] is 100 times less than the Ka, so [A-]/[HA] = 100. After adding enough acid to raise [H+] by a factor of 10,000, the new [H+] would be 10,000 times the original value. Plugging this into the Henderson-Hasselbalch equation, we get pKa = pH + log(100), or pKa = pH + 2. Therefore, the ratio of the different colored forms of the indicator would have originally been 100, and after the addition of the acid, it would be 102.

2. To solve this problem, we need to use the formula M1V1 = M2V2, where M1 is the concentration of the acid, V1 is the volume of the acid used, M2 is the concentration of the base, and V2 is the volume of the base used. We are given the molar mass of KHP and the volume of the base used, so we can calculate the moles of KHP used. Then, by using the molar ratio between KHP and NaOH (1:1), we can calculate the moles of NaOH used. Finally, by dividing the moles of NaOH by the volume of base used, we can calculate the concentration of the base.

3. To determine the moles of HCl needed to neutralize the given amounts of Mg(OH)2 and CaCO3, we need to use the stoichiometric ratios between these substances and HCl. The balanced equation for the neutralization reaction is 2HCl + Mg(OH)2 + CaCO3 -> MgCl2 + CaCl2 +
 

1. What is an acid base titration?

An acid base titration is a laboratory technique used to determine the concentration of an acid or base solution by adding a known amount of a neutralizing agent (titrant) to the solution until the reaction reaches its equivalence point.

2. How do I set up an acid base titration?

To set up an acid base titration, you will need a burette, a titrant solution, a flask containing the solution to be titrated, an indicator, and a stirrer. The titrant is slowly added to the solution while stirring until a color change is observed, indicating the equivalence point has been reached.

3. What is the purpose of an indicator in an acid base titration?

An indicator is used in an acid base titration to signal when the reaction has reached its equivalence point. This is typically done by changing color in response to changes in pH as the titrant is added to the solution.

4. How do I calculate the concentration of the solution being titrated?

The concentration of the solution being titrated can be calculated using the volume and concentration of the titrant, as well as the volume of the solution being titrated. This can be done using the formula M1V1 = M2V2, where M1 is the concentration of the titrant, V1 is the volume of titrant used, M2 is the concentration of the solution being titrated, and V2 is the volume of the solution being titrated.

5. What are some potential sources of error in an acid base titration?

Some potential sources of error in an acid base titration include inaccurate measurements of volumes or concentrations, incomplete mixing of solutions, and incorrect use of indicators. It is important to carefully follow the experimental procedure and use proper techniques to minimize these errors.

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