percent purity percent yield

Determining Mr. Lawson’s Wealth ($)

1. At the front of the room is a Silver coin2. With your phone take a close-up picture of BOTH sides of a coin3. 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 PurityPercent 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 PurityAn analogy

What is the percent purity of gold in gold quartz?

Gold Quartz Weighs 28.0 gWhen refined the gold weighs 6.0 g

V. Percent Purity



Percent Purity =Mass of pure chemical

x 100 %Mass of impure chemical

V. Percent Purity



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

Percent Purity =Mass of pure chemical

x 100 %Mass of impure chemical

Example 1

If 100.0g of FeO produces 12.0g of pure Fe according to the reactionFeO + C + O2 Fe + CO2

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 ZnCl2 + H2

Example 2

Purity Problems

1. Please collect a % Purity worksheet from the front of the class2. 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

Percent Yield =Mass of product attained

x 100 %Mass of product expected

V. Percent YieldAn analogy

What is the percent yield?

30 kernels


30 kernels

Actual yieldPercent yield = Theoretical yield


30 kernels

Actual yieldPercent yield = Theoretical yield = 30


30 kernels

Actual yield = 24Percent yield = Theoretical yield = 30

24 popped corn


30 kernels

Actual yield = 24Percent yield = Theoretical yield = 30

24 popped corn

= 80%

Example 1 – The process

Given the following equation: _____ K2PtCl4 + _____ NH3 _____ Pt(NH3)2Cl2 + _____ KCl

a. Balance the equation. b. Determine the theoretical yield of KCl if you start with 34.5 grams of NH3. c. Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is

the percent yield?


Given the following equation: _____ K2PtCl4 + __2___ NH3 _____ Pt(NH3)2Cl2 + __2___ KCl

a. Balance the equation. b. Determine the theoretical yield of KCl if you start with 34.5 grams of NH3. c. Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is

the percent yield?



a. Balance the equation. b. Determine the theoretical yield of KCl if you start with 34.5 grams of NH3.

151 g KCl c. Starting with 34.5 g of NH3, and you isolate 76.4 g of Pt(NH3)2Cl2, what is

the percent yield?



a. Balance the equation. b. Determine the theoretical yield of KCl if you start with 34.5 grams of NH3.

151 g KCl c. 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

Example 2

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

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 3

Example 4

What mass of CuO is required to make 10.0g of Cu according to the reaction

NH3 + CuO N2 + Cu + H2Oif the reaction has a 58.0% yield?

Example 4

percent purity percent yield

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