When 4.0 mol h2 reacts with excess o2, 3.0 mol h2o are actually produced, what is the percent yield of the reaction? 2h2 + o2 > 2h2o a. 25% b.50% c.75% d.100%

2H2 + O2 --->2H2O

from equation 2 mol 2 mol

given 4 mol 3 mol

How much

we could get

using 4 mol of H2. 4 mol x mol

2 mol H2 gives 2 mol H2O, 4 mol H2 could give 4 mol H2O.

So, 4 mol H2O is theoretical yield.

% yield = (actual yield/theoretical yield)*100% = (3 mol/4 mol)*100% = 75 %

Answer is C. 75%.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.