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Monday February 11, 2013

Monday February 11, 2013. ( Discussion and WS – Percent Yield ). Bell Ringer Monday, 2-11-13. Calcium metal reacts with hydrochloric acid. If 7 mol of calcium are exposed to 16 mol of hydrochloric acid, which is the limiting reactant?. L. E. Ca + HCl æ CaCl 2 + H 2. 2. Have:. 7 moles.

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Monday February 11, 2013

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  1. MondayFebruary 11, 2013 (Discussion and WS – Percent Yield)

  2. Bell RingerMonday, 2-11-13 Calcium metal reacts with hydrochloric acid. If 7 mol of calcium are exposed to 16 mol of hydrochloric acid, which is the limiting reactant? • L • E • Ca + HCl æ CaCl2 + H2 • 2 • Have: • 7 moles • 16 moles • Need: • 7 moles • 14 moles

  3. Announcements Happy Clean Out Your Computer Day!

  4. Announcements I will be available after school today from 4:45 until 5:15.

  5. Percent Yield • The amounts of products calculated in the stoichiometric problems in this chapter so far represent theoretical yields. • The theoretical yield is themaximum amount of product that can be produced from a given amount of reactant. • In most chemical reactions, the amount of product obtained is less than the theoretical yield.

  6. Percent Yield • There are many reasons for this. • Some of the reactant may be used in competing side reactions that reduce the amount of the desired product. • Also, once a product is formed, it often is usually collected in impure form, and some of the product is often lost during the purification process.

  7. Percent Yield • The measured amount of a product obtained from a reaction is called the actual yield of that product. • Chemists are usually interested in the efficiency of a reaction. • The efficiency is expressed by comparing the actual and theoretical yields. • The percent yield is theratio of the actual yield to the theoretical yield, multiplied by 100.

  8. Percent Yield

  9. Percent Yield Sample Problem A chemist runs a reaction based upon the following equation. PCl3 + Cl2æ PCl5 (AB) The chemist starts with 50 grams of PCl3 and produces 73 grams of PCl5. What was the chemist’s percent yield for this reaction? % YIELD = 73 grams 96.4 % = X 100 75.7 grams Determined from a mass to mass stoichiometric calculation

  10. Percent Yield Sample Problem Methanol (CH3OH) can be produced through the reaction of CO and H2. CO + H2æ CH3OH If 100 grams of H2 reacts to produce 750 grams of CH3OH, what is the percent yield for this reaction? • 2 % YIELD = 750 grams 93.8 % = X 100 800 grams Determined from a mass to mass stoichiometric calculation

  11. Worksheet Percent Yield

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