atom economy
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What is atom economy?
The mass of the product that we want as a % of the mass of all the products we make. Atom economy= mass of desired product/ mass of all products x 100 = mass of the reactants
What is the atom economy for the production of CH2Cl2 for the following reaction: 2Cl2+CH4-> CH2Cl2 + 2HCl
A.e.: desired/all x 100 Mr of (ch2cl2) = 12 +2+71 =85 Mr of hcl =1+35.5 =36.5 X2 = 73 85+73 = 158 A.e. 85/158 x100 = 53.8%
what is the importance of atom economy?
Chemical reactions produce unwanted by-products. These are waste products. Improving atom economy can reduce this waste to make it more sustainable , minimize waste and maximize efficiency.
What is the atom economy of addition reactions?
100% atom economy with no by-products
What is the atom economy of substitution and elimination reactions?
<100% atom economy
Ethanol is a valuable chemical. It can be made in a number of ways, one such way is through the fermentation of glucose according to the equation : C6H12O6(aq) -> 2C2H5OH (aq) + 2CO2(g) Calculate the atom economy of the above reaction
A.e: mr desired / mr of all. X100 Mr of ethanol : 24+6+16 =46 Mr of CO2: 12+32 = 44 46x2 +44x2 =180 46x2=92 92/180 x100 =51.1%
Another method used in the production of ethanol is the hydration of ethene as shown in the reaction: C24+H2O -> C2H5OH Compare the atom economy of this reaction to that of the fermentation (51.1) Which reaction is preferable?(industrially)
This reaction is preferable as no waste products or by-products are formed unlike the reaction in a .
Magnesium hydroxide Mg(OH)2 us used to treat indigestion. It is made using magnesium chloride MgCl2 and sodium hydroxide NaOH. There is one by-product of this reaction which is the same as table salt. ‘Write a balanced equation for the reaction and calculate the atom economy of this reaction’
MgCl2+ 2 NaOH -> Mg(OH)2 + 2 NaCl Mr of Mg(OH)2 \: 2+32+24.3 ->58.3 Mr of NaCl \: 35.5 +23 -> 58.5 A.e. : 58.3/58.3+58.5x2 x100 = 33.3%
A scientist reacts 10g of MgCl2 with an excess of NaOH. What is the maximum mass of Mg(OH)2 he could make?
Moles=mass/mr Mol of MgCl2: 10/24.3+71 =0.105mols 1:1 so Mg(OH)2 = 0.105mols Mass = moles x mr = 0.105 x 58.3 6.1g
The actual mass he obtains is 5G what is the yield of the experiment (6.1g was theoretical) in this experiment how does atom economy relate to yield?
5/6.1 x100 =82.0% Atom economy is separate from the yield. The yield of this reaction is high however the atom economy is low.