How to determine the theoretical yield of Boric acid?

Question

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

? · Accepted Answer

2H3BO3 --> B2O3 + 3H2O
1.44g boric acid is in the tube
1.44g H3BO3 / 61.8g/mole = 0.0233moles H3BO3

0.0233moles H3BO3 x (1B2O3 / 2H3PO3) x 69.6g/mole = 0.811g B2O3 = theoretical yield
the ratio of boron oxide : boric acid is in the balanced equation.  this is why one must always have a balanced equation.

actual mass of B2O3 = 10.84g(assuming this is all B2O3) - 10.03g = 0.81g.  not bad
do NOT use mass tube + boric acid - mass tube + product to be the mass of the product

% yield, which will be the next question:  0.81g / 0.811g x 100% = 99.9% which is amazing since this is a school lab and there will be error somewhere

Trending News

How to determine the theoretical yield of Boric acid?

1 Answer