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## Percent Purity Percent Yield

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**Chemicals don’t always exist in pure form.**• The purity of a chemical is indicated as the percentage purity. • The impure substance contains another substance to make the mass higher than a pure substance Percent Purity**Percent Purity**An analogy What is the percent purity of gold in gold quartz? When refined the gold weighs 6.0 g Gold Quartz Weighs 28.0 g**Percent Purity**What is the percent purity of gold in gold quartz? When refined the gold weighs 6.0 g Gold Quartz Weighs 28.0 g**Percent Purity**What is the percent purity of gold in gold quartz? When refined the gold weighs 6.0 g Gold Quartz Weighs 28.0 g**Did you know? Gold Karat is a measure of percentage purity,**not weight. Karats are often mistaken to be a weight measure used by jewelers. Instead karats are a measure of gold's purity. Pure gold is too malleable to be used as-is by jewelers: a ring made of pure gold would bend and loose its shape and be impossible to wear. So jewelers "dilute" gold by mixing it with other stronger metals. One Karat measures the fineness of gold in 1/24 part which is 4.2%. Hence a 18 karat gold ring is made of 18/24 parts of gold, or 75% gold and 25% other metals. Metals added to gold are of cheaper value, so for equals weight, the price of a jewelry item goes up when the karat count goes up too. Gold Karat**If 100.0g of FeO produces 12.0g of pure Fe according to the**reaction FeO + C + O2 Fe + CO2 What is the percentage purity of FeO used? Example 1**What mass of impure zinc metal having a purity of 89.5% is**required to produce 975 mL of hydrogen gas at STP according to the reaction Zn + HCl ZnCl2 + H2 g impure Zn = 3.18g Example 2**Please collect a % Purity worksheet from the front of the**class • Work through the Quick Check and then attempt the practice problem on the back. • Make sure you TRY the practice problem before viewing the answer Purity Problems**Sometimes 100% of the expected amount of products cannot be**attained from a reaction. This can occur because: • The reactants may not all react • They may not be 100% pure • Some of the products are lost due to the experiment procedures Percent Yield**Percent Yield**An analogy What is the percent yield? 30 kernels**What is the percent yield?**Actual yield Percent yield = Theoretical yield 30 kernels**What is the percent yield?**Actual yield Percent yield = Theoretical yield = 30 30 kernels**What is the percent yield?**Actual yield = 24 Percent yield = Theoretical yield = 30 30 kernels 24 popped corn**What is the percent yield?**Actual yield = 24 = 75% Percent yield = Theoretical yield = 30 30 kernels 24 popped corn**Given the following equation:**_____ K2PtCl4 + _____ NH3 _____ Pt(NH3)2Cl2 + _____ KCl • Balance the equation. • Determine the theoretical yield of KCl if you start with 34.5 grams of NH3. • Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is the percent yield? Example 1 – The process**Given the following equation:**_____ K2PtCl4 + __2___NH3 _____ Pt(NH3)2Cl2 + __2___KCl • Balance the equation. • Determine the theoretical yield of KCl if you start with 34.5 grams of NH3. • Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is the percent yield? Example 1 – The process**Given the following equation:**_____ K2PtCl4 + __2___NH3 _____ Pt(NH3)2Cl2 + __2___KCl • Balance the equation. • Determine the theoretical yield of KCl if you start with 34.5 grams of NH3. 151 g KCl • Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is the percent yield? Example 1 – The process**Given the following equation:**_____ K2PtCl4 + __2___NH3 _____ Pt(NH3)2Cl2 + __2___KCl • Balance the equation. • Determine the theoretical yield of KCl if you start with 34.5 grams of NH3. 151 g KCl • Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is the percent yield? % yield = 25.1% Example 1 – The process**Given the following reaction:**CH4 + Cl2 CH3Cl + HCl When 15.0g of CH4 is reacted with Cl2, a total of 29.7g of CH3Cl is formed. What is the percentage yield of the reaction? Example 2**What mass of CuO is required to make 10.0g of Cu according**to the reaction NH3 + CuO N2 + Cu + H2O if the reaction has a 58.0% yield? Example 3**What mass of K2CO3 is produced when 1.50g of KO2 is reacted**according to the reaction, KO2 + CO2 K2CO3 + O2 if the reaction has a 76.0% yield? Example 4