Titration of Sr(OH)2 by HCl. What is the pH?

In summary, the titration of 80.0 mL of 0.100 M Sr(OH)2 by 0.400 M HCl results in a pH of 13 before any HCl is added. Using the Henderson-Hasselbalch equation is not applicable in this scenario. The resulting solution after adding 20 mL of HCl has a pH of 0 and the pH increases with the addition of more HCl. The correct approach for calculating the pH of a mixture of strong acid and strong base is explained on www.titrations.info. The molarity of HCl should be multiplied by two in this calculation.
  • #1
disneychannel
52
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1. COnsider the titration of 80.0 mL of 0.100 M Sr(OH)2 by 0.400 M HCl. Calculate the pH of the resulting solution after the following volumes of HCl have been added.

a. 0.0 mL
b. 20 mL
c.80 mL

Homework Equations


Henderson–Hasselbalch equation or direct -log

The Attempt at a Solution


a) before I added any HCl, I just did the -log(.1)=1 14-1=13 is that correct?
B)i know it is a strong acid & strong base. & i cannot use pKa for Henderson–Hasselbalch equation. what else can i do?
Sr(OH)2 + 2HCl -> 2H2O + Sr
0.092 ... 0.0016 ... 0
-0.008 ... -0.0016 ... +0.008
0.0912 ... 0 ... . 0.008
 
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  • #3
in this do i also have to multiply the HCL molarity by two or only the Sr(OH)2
for letter b i got a pH of 0 and when i did it with 30 mL i got a higher pH...is that normal?
 

1. What is the purpose of titrating Sr(OH)2 with HCl?

The purpose of titrating Sr(OH)2 with HCl is to determine the concentration of the Sr(OH)2 solution. This method is commonly used in analytical chemistry to determine the concentration of a solution by reacting it with a known volume and concentration of another solution. In this case, the HCl solution is added to the Sr(OH)2 solution until the reaction is complete, allowing for the concentration of the Sr(OH)2 solution to be calculated.

2. How is the titration carried out?

The titration of Sr(OH)2 with HCl is carried out by adding the HCl solution to the Sr(OH)2 solution in small increments using a burette. The reaction is monitored using a pH meter or an indicator such as phenolphthalein, which changes color when the reaction is complete. The endpoint of the titration is determined when the indicator changes color, indicating that all of the Sr(OH)2 has been neutralized.

3. What is the equation for the reaction between Sr(OH)2 and HCl?

The reaction between Sr(OH)2 and HCl can be represented by the following equation: Sr(OH)2 + 2HCl → SrCl2 + 2H2O. This reaction is a neutralization reaction, where the acid (HCl) reacts with the base (Sr(OH)2) to form a salt (SrCl2) and water (H2O).

4. How does the pH change during the titration?

The pH of the solution starts off basic due to the presence of Sr(OH)2, and decreases as the HCl is added. As the reaction nears completion, the pH will begin to decrease more rapidly until it reaches the endpoint, where the pH will be approximately neutral (pH 7). This change in pH is due to the neutralization of the base by the acid, resulting in a decrease in the concentration of hydroxide ions (OH-) and an increase in the concentration of hydrogen ions (H+).

5. How is the concentration of Sr(OH)2 calculated from the titration data?

The concentration of Sr(OH)2 can be calculated by using the volume and concentration of the HCl solution, and the volume of Sr(OH)2 solution used in the titration. The equation used is: M1V1 = M2V2, where M1 is the concentration of Sr(OH)2, V1 is the volume of Sr(OH)2 used, M2 is the concentration of HCl, and V2 is the volume of HCl used. By rearranging the equation, the concentration of Sr(OH)2 can be calculated as: M1 = (M2V2)/V1.

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