Question #16ddb
1 Answer
Explanation:
Percent yield problems are all about how much product should be formed by the reaction versus how much product is actually formed.
As you know, percent yield is defined as the actual yield of the reaction, which tells you how much product is actually produced, divided by the theoretical yield of the reaction, which tells you how much product should be produced, and multiplied by
#color(blue)("% yield" = "actualy yield"/"theoretical yield" xx 100)#
Now, what does should be produced mean?
The theoretical yield of a reaction is determined by assuming that all the moles of reactants that take part in the reaction are converted to product.
Simply put, theoretical yield is what you get when the reaction has a
Now, take a look at the balanced chemical equation
#"CH"_3"COOH"_text((l]) + "C"_5"H"_11"OH"_text((l]) -> "CH"_3"COOC"_5"H"_text(11(l]) + "H"_2"O"_text((l])#
Acetic acid,
This tells you that the reaction will always consume equal numbers of moles of the two reactants.
Now, you need to determine if one of the two reactants will act as a limiting reagent. To do that, use their molar masses to determine how many moles you're mixing
#3.58 color(red)(cancel(color(black)("g"))) * ("1 mole CH"_3"COOH")/(60.05color(red)(cancel(color(black)("g")))) ="0.05962 moles CH"_3"COOH"#
#4.75 color(red)(cancel(color(black)("g"))) * ("1 mole C"_5"H"_11"OH")/(88.15 color(red)(cancel(color(black)("g")))) = "0.05389 moles C"_5"H"_11"OH"#
Notice that you have fewer moles of isoamyl alcohol than you have of acetic acid. Since the reaction consumes the reactants in a
In other words, isoamyl alcohol will be a limiting reagent, since it will bring the reaction to a halt before all the moles of acetic acid are consumed.
Now, isoamyl acetate is produced in a
Therefore, you can say that
#0.05389 color(red)(cancel(color(black)(" moles C"_5"H"_11"OH"))) * ("1 mole CH"_3"COOC"_5"H"_11)/(1color(red)(cancel(color(black)("mole C"_5"H"_11"OH")))) = "0.05389 moles CH"_3"COOC"_5"H"_11#
The reaction's theoretical yield will be determined by assuming that all these moles of product are actually formed - remember, theoretical yield is equivalent to
Use isoamyl acetate's molar mass to find how many grams would contain this many moles
#0.05389 color(red)(cancel(color(black)("moles"))) * "130.19 g"/(1color(red)(cancel(color(black)("mole")))) = "7.016 g"#
However, you know that the reaction has a
This means that you can write
#45% = "actual yield"/"7.016 g" xx 100#
Rearrange to get
#"actual yield" = 45/100 * "7.016 g" = color (green)("3.16 g")#
The answer is rounded to three sig figs.