[plasticfood]

for this lab, i weight out 31.46g of borax and dissolve it in 50mL of water. So its concentration is 1.65M, right?? then i took out 5mL of the borax solution and add it to 5mL of water. 20mL of distilled water and few drops of coloring are added to the water + borax solution. we titrate with .5469M HCL until the color changed. for the first trail, it took 35mL of HCL to titrate to its end point. this may seem like a simple question, but how do i solve for moles of borate?  

ok is this it? (1.65M)(5mL) = (M2)(30mL), solve for M2 then (M2)*(.035L) = moles of borate??

[plasticfood]

ok i got the first part down. now i need to know how to solve for the solubility of borax. these are the directions in the book: http://imgur.com/HjfPk
but i don't really understand it. it says to calculate the concentration of the tetraborate anions, so is that the solubility??    

the temp for the first trial is 50 C.

[UG]

it says to calculate the concentration of the tetraborate anions, so is that the solubility??   

Yes finding the tetraborate anion concentration would give you the solubility

[plasticfood]

i'm kind of stuck on this one. so i have the moles of borate and then convert that to moles of H3BO3. i know concentration is mol/liters, what exactly is the liters of? or am i completely on the wrong track?

[UG]

so i have the moles of borate and then convert that to moles of H3BO3. i know concentration is mol/liters, what exactly is the liters of? or am i completely on the wrong track?

When you say you have moles of borate, do you mean you have moles of B₄O₅(OH)₄^2- ? I just wanted to be clear. And if you do have moles of B₄O₅(OH)₄^2- you should be able to work out it's concentration since the instructions mentioned that you titrated with a known volume of the saturated borax solution. The concentration of B₄O₅(OH)₄^2- is then simply moles of B₄O₅(OH)₄^2- divided by its volume.

[plasticfood]

yeah that's right. thanks so much!