A student prepared 5.00 mL of borax solution at 59.2 C. He diluted the solution in a flask and titrated it to an endpoint with 27.05 mL of 0.500 M HCl. What is the saturation concentration of borate ions?
This is a question in relation to a lab we did of gibbs free energy-solubility. I have no idea where to start.
Here is a site i expect explains all of your questions in detail. Click on the first PDF document, Chemistry 212 lab.
http://www.google.com/search?q=titrate+borax&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
To find the saturation concentration of borate ions in the solution, we can use the concept of stoichiometry and the balanced chemical equation between borax and hydrochloric acid (HCl). Here's how you can approach this problem step by step:
1. Write the balanced chemical equation for the reaction between borax and hydrochloric acid:
Na2B4O7 + 2HCl -> 2NaCl + 4H3BO3
This equation shows that one mole of borax (Na2B4O7) reacts with two moles of hydrochloric acid (HCl) to produce two moles of sodium chloride (NaCl) and four moles of boric acid (H3BO3).
2. Convert the volume of HCl used for the titration from milliliters to liters:
27.05 mL = 0.02705 L
3. Calculate the number of moles of HCl used:
moles HCl = concentration (M) x volume (L)
moles HCl = 0.500 M x 0.02705 L
4. Since the reaction is 1:2 ratio, the number of moles of borax used will be half of the moles of HCl used as per stoichiometry:
moles borax = 1/2 moles HCl
5. Calculate the concentration of borate ions in the original 5.00 mL of borax solution:
concentration (M) = moles / volume (L)
concentration (M) = moles borax / 0.005 L (5.00 mL converted to L)
Now, let's plug in the values we obtained:
moles HCl = 0.500 M x 0.02705 L = 0.013525 moles
moles borax = 1/2 moles HCl = 0.0067625 moles
concentration (M) = 0.0067625 moles / 0.005 L = 1.3525 M
Therefore, the saturation concentration of borate ions in the borax solution is approximately 1.3525 M.