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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: robkule424 on February 16, 2011, 04:58:55 PM

Title: How to determine the theoretical yield of Boric acid?
Post by: robkule424 on February 16, 2011, 04:58:55 PM

I missed a few days of school with the flu and now I'm a little lost in chemistry

We did a lab and it's asking me to


"Calculate the amount of Boron oxide that theoretically should form from the amount of boric acid in your test tube. Show work." -.-

Ok so we filled out a data table of all of the weights of our substances

Initial mass of test tube = 10.03g
Mass of tube + Boric Acid = 11.47g
Mass of tube + Product = 10.84g

Then the next question says,

What is your actual yield of boron oxide?

Here are the equations it gives

2H3BO3->B203+3H20


Any help would be greatly appreciated, because honestly, she did a terrible job of explaining the actual/theoretical yield to me and I really cannot get this on my own.

Thanks

Title: Re: How to determine the theoretical yield of Boric acid?
Post by: rabolisk on February 16, 2011, 06:14:44 PM

2H₃BO₃  :rarrow: B₂O₃ + 3H₂O

What does this equation mean? Specifically what do the coefficients mean?

Title: Re: How to determine the theoretical yield of Boric acid?
Post by: Nobby on February 17, 2011, 09:36:58 AM

You need the molekular weights from Boric acid and Boron oxide.

From the equation you get the coefficients.

you can calculate m1/(x*M1) = m2/(y*M2)

You know the mass of boric acid m1, the coefficient x is 2. You has to get the molecular weights and you can calculate m2

Then you can compare how much you get after the Thermolysis.

Title: Re: How to determine the theoretical yield of Boric acid?
Post by: robkule424 on February 17, 2011, 04:54:51 PM

Alright I managed to get the theoretical yield and the actual yield, as well as the percent error. Next, it's asking me to find out the limiting reagent. Would it be 2H3BO3?

Also how do you type the smaller numbers on the keyboard. Like how rabolisk posted with the equation.

Thanks.

Title: Re: How to determine the theoretical yield of Boric acid?
Post by: Nobby on February 18, 2011, 12:45:36 AM

The first question makes no sense, because you have only one reagent, the boric acid.

The second ist to write H₃BO₃ use the Button "(sub)"