Chemistry Help. Please!

[LieToMe]

I'm having some difficulty with three particular problems are I really need some guidance on these. I know what to do, but I do not know if I am doing it correctly:notrust Feel free to do one problem or all three problems. Any help is greatly appreciated. Thank You!

When 19.2 grams of zinc is placed in 39.2 ml of 10.2 M aluminum nitrate solution, how many grams of aluminum are formed if there is a 93.4 % yield.


34.3 grams of iron are placed in 321 ml of phosphoric acid. If 62.0 grams of solid product are formed, what is the molarity of the acid? (an Iron (II) compound is formed)


If exactly 3.00 moles of Al were mixed with excess HCl, how many grams of each product would be made?

[cygnus]

I won't do the problems, but I'll tell you how.

WRITE DOWN THE FORMULA
3Zn + 2Al(NO3)3 --> 3Zn(NO3)2 + 2Al

WORK OUT MOLES OF EACH COMPONENT
19.2/Molecular weight zinc = moles of zinc

0.0392 x 10.2 = moles of Aluminium nitrate.

FIND THE LIMITING REACTANT
moles of zinc/moles of aluminium nitrate = ~

If its > 1.5, aluminium nitrate is the limiting reactant, if its <1.5, zinc is the limiting reactant.

WORK OUT HOW MANY MOLES OF THE PRODUCT IS FORMED
moles of limiting reactant -> moles of product (if limiting reactant is zinc, moles aluminium = 2/3 x moles zinc nitrate, if aluminium nitrate, moles aluminium = moles aluminium nitrate)

MULTIPLY NUMBER OF MOLES BY MOLECULAR WEIGHT OF ALUMINIUM

and then multiply by 0.934 for the particular yield.

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WRITE DOWN THE FORMULA
3Fe + 2H3PO4 --> Fe3(PO4)2 [since its Fe(II)] + 3H2 (or multiply the whole thing by 2 if you don't like fractions)

WORK OUT MOLES OF THE REACTANTS

WORK OUT MOLES OF PRODUCT/S

USE FORMULA TO FIGURE OUT HOW MANY MOLES OF PHOSPHORIC ACID etc etc

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Al + 3HCl --> AlCl3 + 1.5H2

3 moles AlCl and 4.5 moles of H2 formed, then multiply by the molecular weight of each.





I didn't check anything, so don't blame me if its wrong.