Contents
Key Stage 4
Meaning
Yield is the mass of product in a chemical reaction.
About Yield
- The theoretical yield of product form a chemical reaction can be calculated using the balanced symbol equation and the relative formula masses of all the molecules involved.
- The experimental yield from a chemical reaction is often not as large as the theoretical yield because not all of the reactants will react. This experimental yield is often expressed as a percentage of the theoretical yield and is known as the Percentage Yield.
Examples
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Calculate the yield of Magnesium Oxide given 48g of Magnesium and excess Oxygen. |
Find the yield of Water when 320g of Methane reacts with excess Oxygen. |
Find the yield of Sodium Chloride when 7.3 of Hydrochloric Acid reacts with excess Sodium Hydroxide. |
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Write the Balanced Symbol Equation 2Mg + O2 → 2MgO |
Write the Balanced Symbol Equation CH4 + 2O2 → 2H2O + CO2 |
Write the Balanced Symbol Equation NaOH + HCl → NaCl + H2O |
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Find the Relative Formula Mass of the relevant reactants and product. Mr of Mg = 24g Mr of MgO = 40g |
Find the Relative Formula Mass of the relevant reactants and product. Mr of CH4 = 16g Mr of H2O = 18g |
Find the Relative Formula Mass of the relevant reactants and product. Mr of NaOH = 40g Mr of HCl = 36.5g Mr of NaCl = 58.5g |
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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 |