Question #ac8d7
1 Answer
Explanation:
Start by writing the balanced chemical equation that describes this double-replacement reaction
#"Na"_ 3"PO"_ (4(aq)) + "AlCl"_ (3(aq)) -> "AlPO"_ (4(s)) darr + 3"NaCl"_ ((aq))#
Notice that in order to produce
You can use the molar masses of the three chemical species
#M_ ("M Na" _ 3"PO"_ 4) = "163.94 g mol"^(-1)# #M_ ("M AlCl"_ 3) = "133.34 g mol"^(-1)# #M_ ("M AlPO" _4) = "121.953 g mol"^(-1)#
to say that in order for the reaction to produce
Now, you know that aluminium chloride is in excess, which implies that all the mass of sodium phosphate present in your sample will actually react.
This means that at
#33.4 color(red)(cancel(color(black)("g Na"_3"PO"_4))) * "121.953 g AlPO"_4/(163.94color(red)(cancel(color(black)("g Na"_3"PO"_4)))) = "24.846 g AlPO"_4#
This represents the reaction's theoretical yield.
However, you know that your reaction produced
To find the reaction's percent yield, simply divide the actual yield by the theoretical yield and multiply the result by
In your case, you have
#"% yield" = (18.4 color(red)(cancel(color(black)("g"))))/(24.846color(red)(cancel(color(black)("g")))) * 100% = color(darkgreen)(ul(color(black)(74.1%)))#
The answer is rounded to three sig figs.