# Chemstry help-whats atom economy and percentage yield

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#1
as level chemistry also
What are advantages for sustainability of processes with high atom economy
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5 years ago
#2
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5 years ago
#3
% atom economy
- measures efficiency of an equation / how many atoms are lost / how wasteful, so how green it is
Calculated by:
molar mass of desired product / molar mass of all reagents x 100% = ... %

% yield
find moles of a reagent
convert figure if need be, from ratio 1:2 double 2:1 half, 1:3 triple and so on and so forth
find mass of product (whose actual mass you know)
this is your theoretical maximum mass

then calculated by:
actual mass / theoretical maximum mass x 100% = ... %

In A2 you are required to manipulate that equation to a degree.
So rearrange / do backwards etc etc.

Edit: when saying what atom economy is for, these might not be model / markscheme answers.
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5 years ago
#4
So in summary:
% atom economy = Mr of desired product / Mr of reagents x 100%

% yield
1) n = m / Mr, n = c x v (in dm3, so /1000 if in cm3)
Find moles of a reagent
2) In the ratio, multiply/divide so that the first number in the ratio equals the second number.
A ratio of 1:2, you must double.
3) m = n x Mr
Find mass of a product (whose mass which is produced you know) = theoretical maximum mass

Then % yield = actual mass / theoretical maximum mass x 100%
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