Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: GoldAnt on October 03, 2005, 10:05:56 PM

Title: Titration of Ca(OH) and HClO4
Post by: GoldAnt on October 03, 2005, 10:05:56 PM
Ok, heres is the question.

Consider two solutions. One solution is 0.1115 M CA(OH)2. The other is 0.1050 M HClO4.
A. Write a balanced, net ionic equation for the reaction between the two solutions.

B. How many mL of Ca(OH)2 willbe required to neutralize 25.00 mL of the HCLO4?
 
C. If a student starts to titrate 31.39 mL of the Ca(OH)2 solution with HClO4 and stops the titration after only 23.81 mL of HClO4 have been added, then
 1. How many moles of H+ have been added?
 2. How many moles of OH- are left unreacted?
--------
Now, im a bit confused, I think im supposed to do the equation doing a redox equation right? Where I split it into half equations and then put them back together to cancel out electrons. But I must be putting the half equations together wrong because I get all the electrons on one side. Im supposed to use 2HClO4 and Ca(OH)2 for the half equations right...? And im not quite sure what titration means... :/

Title: Re:Titration of Ca(OH) and HClO4
Post by: Mitch on October 03, 2005, 10:10:38 PM
First decide whether HClO4 is a strong/weak acid and Ca(OH)2 a strong/weak base.
Title: Re:Titration of Ca(OH) and HClO4
Post by: GoldAnt on October 03, 2005, 10:11:47 PM
HClO4 is a very strong acid, and Ca(OH)2 is a strong base.
Title: Re:Titration of Ca(OH) and HClO4
Post by: Mitch on October 03, 2005, 10:14:17 PM
So, whenever you add one mole of Ca(OH)2 it will react with two moles of HCLO4.

Did you follow these steps when you tried to balance your equation.

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2F66.49.132.100%2Fattachments%2Fbalance.gif&hash=393803a0f353e440d3a2aad2915f8fb72a15c089)
Title: Re:Titration of Ca(OH) and HClO4
Post by: GoldAnt on October 03, 2005, 10:19:38 PM
Yep, those are the steps i've been trying to do. I think im setting up the half equations wrong. Heres what I get for each half.

6H2O + Ca(OH)2 --> Ca(ClO4)2 + 12H+ + 12e-

2HClO4 --> Ca(ClO4)2 + 2H+ + 2e-

:/
Title: Re:Titration of Ca(OH) and HClO4
Post by: Mitch on October 03, 2005, 10:36:27 PM
Your reaction is wrong. :P

Ca(OH)2 + HClO4 -> Ca(ClO4)2 + H2O. I'll leave it to you to balance that.
Title: Re:Titration of Ca(OH) and HClO4
Post by: sdekivit on October 04, 2005, 02:22:40 AM
this is an acid-base-reaction --> no halfreactions please :(

we just get the reation Ca(OH)2 + 2H(+) --> Ca2+(aq) + H2O because both are strong and thus ionize completely.