Percents

We performed an experiment in which the theoretical yield of the desired
chemical is 143.2 liters.  If the percent yield of the actual experiment is
62%, how much of the chemical did we really end up with?

87.78 liters

Solution Steps:

The percent yield is actual / theoretical, so we have

.62 = x / 143.2

Multiplying both sides by 143.2 on a calculator gives:

x = 88.784.

So, how should we present the answer?

The units are liters -- Why? The percent has no units and the 143.2 is measured in liters, so x must also be in liters to balance out the =.
We should keep 4 sig figs-- Why?143.2 liters is a measurement, and we only have 4 sig figs to work with. However, if we were given an indication that the 62% figure was not an exact number, we would only keep 2 sig figs in our answer because .62 has only 2 sig figs.

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Developed by

Shodor
in cooperation with the Department of Chemistry,
The University of North Carolina at Chapel Hill