Determining Mr. Lawson’s Wealth ($) 1.At the front of the room is a Silver coin 2.With your phone take a close-up picture of BOTH sides of a coin 3.Examine the picture CLOSELY and determine how many TOTAL atoms of silver make up Mr. Lawson’s net worth! 4.DO NOT OPEN THE CASE, Mr. Lawson is a new teacher and does not get paid very much… 

Percent Purity Not all materials are pure (entirely made of JUST the chemical we are interested in) In order to find the purity of a substance we use the following formula…

Answer:

Percent Purity Percent Yield

Percent Purity 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

V. Percent Purity An analogy What is the percent purity of gold in gold quartz? Gold Quartz Weighs 28.0 g When refined the gold weighs 6.0 g

V. Percent Purity What is the percent purity of gold in gold quartz? Gold Quartz Weighs 28.0 g When refined the gold weighs 6.0 g Percent Purity= Mass of pure chemical x100 % Mass of impure chemical

V. Percent Purity What is the percent purity of gold in gold quartz? Gold Quartz Weighs 28.0 g When refined the gold weighs 6.0 g Percent Purity= 6.0 g pure gold x 100% = 21% 28.0 g impure gold

Gold Karat 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.

Percent Purity = Mass of pure chemical x100 % Mass of impure chemical

Example 1 If 100.0g of FeO produces 12.0g of pure Fe according to the reaction FeO + C + O 2  Fe + CO 2 What is the percentage purity of FeO used?

Example 1

Example 2 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  ZnCl 2 + H 2

Example 2

Purity Problems 1.Please collect a % Purity worksheet from the front of the class 2.Work through the Quick Check and then attempt the practice problem on the back. 3.Make sure you TRY the practice problem before viewing the answer

Percent Yield Sometimes 100% of the expected amount of products cannot be attained from a reaction. This can occur because: 1.The reactants may not all react They may not be 100% pure 2.Some of the products are lost due to the experiment procedures

Percent Yield = Mass of product attained x100 % Mass of product expected

V. Percent Yield An analogy What is the percent yield? 30 kernels

What is the percent yield? 30 kernels Actual yield Percent yield = Theoretical yield

What is the percent yield? 30 kernels Actual yield Percent yield = Theoretical yield = 30

What is the percent yield? 30 kernels Actual yield = 24 Percent yield = Theoretical yield = popped corn

What is the percent yield? 30 kernels Actual yield = 24 Percent yield = Theoretical yield = popped corn = 80%

Example 1 – The process Given the following equation: _____ K 2 PtCl 4 + _____ NH 3  _____ Pt(NH 3 ) 2 Cl 2 + _____ KCl a.Balance the equation. b.Determine the theoretical yield of KCl if you start with 34.5 grams of NH 3. c.Starting with 34.5 g of NH 3, and you isolate 76.4 g of Pt(NH 3 ) 2 Cl 2, what is the percent yield?

Example 1 – The process Given the following equation: _____ K 2 PtCl 4 + __2___ NH 3  _____ Pt(NH 3 ) 2 Cl 2 + __2___ KCl a.Balance the equation. b.Determine the theoretical yield of KCl if you start with 34.5 grams of NH 3. c.Starting with 34.5 g of NH 3, and you isolate 76.4 g of Pt(NH 3 ) 2 Cl 2, what is the percent yield?

Example 1 – The process Given the following equation: _____ K 2 PtCl 4 + __2___ NH 3  _____ Pt(NH 3 ) 2 Cl 2 + __2___ KCl a.Balance the equation. b.Determine the theoretical yield of KCl if you start with 34.5 grams of NH g KCl c.Starting with 34.5 g of NH 3, and you isolate 76.4 g of Pt(NH 3 ) 2 Cl 2, what is the percent yield?

Example 1 – The process Given the following equation: _____ K 2 PtCl 4 + __2___ NH 3  _____ Pt(NH 3 ) 2 Cl 2 + __2___ KCl a.Balance the equation. b.Determine the theoretical yield of KCl if you start with 34.5 grams of NH g KCl c.Starting with 34.5 g of NH 3, and you isolate 76.4 g of Pt(NH 3 ) 2 Cl 2, what is the percent yield? % yield = 25.1%

Example 1

Example 2 Given the following reaction: CH 4 + Cl 2  CH 3 Cl + HCl When 15.0g of CH 4 is reacted with Cl 2, a total of 29.7g of CH 3 Cl is formed. What is the percentage yield of the reaction?

Example 2

Example 3 What mass of K 2 CO 3 is produced when 1.50g of KO 2 is reacted according to the reaction, KO 2 + CO 2  K 2 CO 3 + O 2 if the reaction has a 76.0% yield?

Example 3

Example 4 What mass of CuO is required to make 10.0g of Cu according to the reaction NH 3 + CuO  N 2 + Cu + H 2 O if the reaction has a 58.0% yield?

Example 4