Difference between revisions of "Atom Economy"
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+ | {| class="wikitable" | ||
+ | | style="height:20px; width:300px; text-align:center;" | | ||
+ | Calculate the '''atom economy''' for [[product|producing]] [[Ammonia]] in the following [[Chemical Reaction|reaction]]: | ||
+ | N<sub>2</sub>(g) + 3H<sub>2</sub>(g) ⇌ 2NH<sub>3</sub>(g) | ||
+ | | style="height:20px; width:300px; text-align:center;" | | ||
+ | Calculate the '''atom economy''' for [[product|producing]] [[Calcium Oxide]] in the following [[Chemical Reaction|reaction]]: | ||
+ | CaCO<sub>3</sub>(s) → CaO(s) + CO<sub>2</sub>(g) | ||
+ | | style="height:20px; width:300px; text-align:center;" | | ||
+ | Calculate the '''atom economy''' for [[product|producing]] [[Sodium Chloride]] in the following [[Chemical Reaction|reaction]]: | ||
+ | HCl(aq) + NaOH(aq) → NaCl(aq) + H<sub>2</sub>O(l) | ||
+ | |- | ||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the [[Relative Formula Mass]] of the relevant [[reactant]]s and [[product]].''' | ||
+ | |||
+ | M<sub>r</sub> of N<sub>2</sub> = 28g | ||
+ | |||
+ | M<sub>r</sub> of H<sub>2</sub> = 2g | ||
+ | |||
+ | M<sub>r</sub> of NH<sub>3</sub> = 17g | ||
+ | |||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the [[Relative Formula Mass]] of the relevant [[reactant]]s and [[product]].''' | ||
+ | |||
+ | M<sub>r</sub> of CaCO<sub>3</sub> = 100g | ||
+ | |||
+ | M<sub>r</sub> of CaO = 56g | ||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the [[Relative Formula Mass]] of the relevant [[reactant]]s and [[product]].''' | ||
+ | |||
+ | M<sub>r</sub> of HCl = 36.5g | ||
+ | |||
+ | M<sub>r</sub> of NaOH = 40g | ||
+ | |||
+ | M<sub>r</sub> of NaCl = 58.5g | ||
+ | |- | ||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the total [[mass]] of [[reactant]]s needed and the total [[mass]] of the desired [[product]].''' | ||
+ | |||
+ | Mass of Reactants = 28 + 3 x 2 | ||
+ | |||
+ | Mass of Reactants = 34g | ||
+ | |||
+ | Mass of desired Product = 2 x 17 | ||
+ | |||
+ | Mass of desired Product = 34g | ||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the total [[mass]] of [[reactant]]s needed and the total [[mass]] of the desired [[product]].''' | ||
+ | |||
+ | Mass of Reactants = 100g | ||
+ | |||
+ | Mass of desired Product = 56g | ||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the total [[mass]] of [[reactant]]s needed and the total [[mass]] of the desired [[product]].''' | ||
+ | |||
+ | Mass of Reactants = 36.5 + 40 | ||
+ | |||
+ | Mass of Reactants = 76.5g | ||
+ | |||
+ | Mass of desired Product = 58.5g | ||
+ | |- | ||
+ | |||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the number of [[mole]]s supplied of the known [[mass]].''' | ||
+ | |||
+ | No. [[Mole]]s = <math>\frac{Mass}{M_r}</math> | ||
+ | |||
+ | No. [[Mole]]s = <math>\frac{48}{24}</math> | ||
+ | |||
+ | No. [[Mole]]s = 2 mol | ||
+ | |||
+ | Therefore 2 [[mole]]s of MgO is produced. | ||
+ | |||
+ | 2 [[mole]]s of MgO = 40x2 | ||
+ | |||
+ | '''Yield''' = 80g | ||
+ | |||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the number of [[mole]]s supplied of the known [[mass]].''' | ||
+ | |||
+ | No. [[Mole]]s = <math>\frac{Mass}{M_r}</math> | ||
+ | |||
+ | No. [[Mole]]s = <math>\frac{320}{16}</math> | ||
+ | |||
+ | No. [[Mole]]s = 20 mol | ||
+ | |||
+ | Therefore 40 [[mole]]s of H<sub>2</sub>O are produced. | ||
+ | |||
+ | 40 [[mole]]s of CO<sub>2</sub> = 18x40 | ||
+ | |||
+ | '''Yield''' = 720g | ||
+ | |||
+ | | style="height:20px; width:300px; text-align:left;" | | ||
+ | '''Find the number of [[mole]]s supplied of the known [[mass]].''' | ||
+ | |||
+ | No. [[Mole]]s = <math>\frac{Mass}{M_r}</math> | ||
+ | |||
+ | No. [[Mole]]s = <math>\frac{7.3}{36.5}</math> | ||
+ | |||
+ | No. [[Mole]]s = 0.2 mol | ||
+ | |||
+ | Therefore 0.2 [[mole]] of [[Sodium Chloride]] is produced. | ||
+ | |||
+ | 0.2 [[mole]] of NaCl = 11.7g | ||
+ | |||
+ | '''Yield''' = 11.7g | ||
+ | |} |
Revision as of 19:42, 27 January 2019
Contents
Key Stage 4
Meaning
Atom Economy is the percentage of atoms in the reactants which ends up in the desired products.
About Atom Economy
- During a chemical reaction there is often more than one product. When there is more than one product often one is desired and one is a waste product that must be disposed of.
- To reduce costs and increase the efficiency of a process chemical engineers design systems that produce the maximum amount of a desired product and a minimum amount of waste products.
Atom Economy Equation
Percentage Atom Economy = [(Relative Formula Mass of Desired Product)/(Sum of Relative Formula Masses of Reactants)] x 100%
% Atom Economy = \(frac{M_desiredproduct}{M_allreactants}\)
Where:
Mdesiredproduct = Relative Formula Mass of Desired Product
Mallreactants = Sum of Relative Formula Masses of Reactants
Example Calculations
Calculate the atom economy for producing Ammonia in the following reaction: N2(g) + 3H2(g) ⇌ 2NH3(g) |
Calculate the atom economy for producing Calcium Oxide in the following reaction: CaCO3(s) → CaO(s) + CO2(g) |
Calculate the atom economy for producing Sodium Chloride in the following reaction: HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) |
Find the Relative Formula Mass of the relevant reactants and product. Mr of N2 = 28g Mr of H2 = 2g Mr of NH3 = 17g |
Find the Relative Formula Mass of the relevant reactants and product. Mr of CaCO3 = 100g Mr of CaO = 56g |
Find the Relative Formula Mass of the relevant reactants and product. Mr of HCl = 36.5g Mr of NaOH = 40g Mr of NaCl = 58.5g |
Find the total mass of reactants needed and the total mass of the desired product. Mass of Reactants = 28 + 3 x 2 Mass of Reactants = 34g Mass of desired Product = 2 x 17 Mass of desired Product = 34g |
Find the total mass of reactants needed and the total mass of the desired product. Mass of Reactants = 100g Mass of desired Product = 56g |
Find the total mass of reactants needed and the total mass of the desired product. Mass of Reactants = 36.5 + 40 Mass of Reactants = 76.5g Mass of desired Product = 58.5g |
Find the number of moles supplied of the known mass. No. Moles = \(\frac{Mass}{M_r}\) No. Moles = \(\frac{48}{24}\) No. Moles = 2 mol Therefore 2 moles of MgO is produced. 2 moles of MgO = 40x2 Yield = 80g |
Find the number of moles supplied of the known mass. No. Moles = \(\frac{Mass}{M_r}\) No. Moles = \(\frac{320}{16}\) No. Moles = 20 mol Therefore 40 moles of H2O are produced. 40 moles of CO2 = 18x40 Yield = 720g |
Find the number of moles supplied of the known mass. No. Moles = \(\frac{Mass}{M_r}\) No. Moles = \(\frac{7.3}{36.5}\) No. Moles = 0.2 mol Therefore 0.2 mole of Sodium Chloride is produced. 0.2 mole of NaCl = 11.7g Yield = 11.7g |