1 / 21

Stoichiometry

Stoichiometry. Inquiry Activity. Using 20 white balls (H), make 10 diatomic molecules. Make diatomic molecules using the yellow balls as well. Without looking, have someone choose 10 molecules at random.

avital
Download Presentation

Stoichiometry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Stoichiometry

  2. Inquiry Activity • Using 20 white balls (H), make 10 diatomic molecules. Make diatomic molecules using the yellow balls as well. • Without looking, have someone choose 10 molecules at random. • Out of the chosen molecules, pair up the reactants using the following chemical equation: Y2 + 3W2 2YW3 • Pair up reactants until you run out of one of the reactants. This is your limiting reagent. • Repeat the activity and see if you get the same results

  3. Review – Balance these equations • N2 + H2 NH3 • H2S + O2  SO2 + H2O • H2 + I2  HI

  4. Stoichiometry • Study of the amount of substances consumed or produced in a chemical reaction – Requires Balanced Equations! Reactants  Products

  5. Stoichiometry Reactants and Products ALWAYS the same Reactants and Products SOMETIMES the same Number of molecules Moles Volume • Number of Atoms • Mass N2 + 3H2 2NH3 Atoms 2 N 6 H = 2 N + 6 H Mass 28g + 6g = 34g Number of molecules 1 molecule 3 molecules 2 molecules Moles 1mole 3 moles 2moles Volume 22.4L 64.2L 44.8L

  6. What is conserved in each reaction?Atoms? Mass? Number of Molecules? Moles? • H2 + O2 H2O • H2 + I2  2HI • C2H2 + O2  CO2 + H2O

  7. Calculations • Mole ratio: Conversion factor using the coefficients of balanced chemical equations • Used to convert between moles of reactant and moles of product N2 + 3H2 2NH3 1 mol 3 mol 2mol So….. 1 mol N22 mol NH33mol H2 3 mol H21 mol N22 mol NH3

  8. How many moles of ammonia (NH3) are produced when 0.6mol nitrogen (N2) reacts with hydrogen (H2)? • Write the chemical reaction: • What conversion do you use to get from N2 to NH3? • Solve

  9. Al + O2 Al2O3 How many moles of aluminum are needed to form 3.7mol of aluminum oxide? How many moles of oxygen are required to react completely with 14.8mol Al? How many moles of Al2O3 are formed when 0.78 mol O2 reacts with aluminum?

  10. Mole – Mass Calculations • Calculate the number of grams of NH3 produced by the reaction of 5.40g hydrogen with an excess of nitrogen. • What is the chemical reaction? • Conversion gram hydrogen  mol hydrogen  mol NH3  gram NH3

  11. CaC2 + H2O  C2H2 + Ca(OH)2 • How many grams of acetylene gas (C2H2) are produced by adding water to 5.00g CaC2? • How many moles of CaC2 are needed to react completely with 49.0g H2O?

  12. Other conversions… • Number of particles - 1 mol 6.02x1023 particles • Volume of gas at STP - 1 mol 22.4L So you should be able to convert: mass-mass mol-mol mass-mol mol-number of particles mol-volume of gas at STP ALYWAYS CONVERT THROUGH USING MOLES!!!

  13. How many molecules of oxygen are produced when 29.2g of water is decomposed? H2O  H2 + O2 • How many grams of nitrogen dioxide must react with water to produce 5.0x1022 molecules of nitrogen monoxide? NO2 + H2O  HNO3 + NO

  14. How many liters of nitrogen dioxide are produced when 34L of oxygen reacts with excess nitrogen monoxide? NO + O2 NO2

  15. How much do you actually get? • In any reaction, the amount of product formed is limited by the amount of reagents…. • Limiting Reagent: -determines the amount of product that can be formed -is completely used up in the reaction • Excess Reagent: - reactant is not completely used up

  16. What is the limiting reagent when 80g of Cu reacts with 25g of S in the following reaction? Cu + S  Cu2S • Balance the equation • Convert grams to moles • What is the mole ratio between Cu and S? • Take the given mole quantity for one reagent (#2), multiply it by the mole ratio (#3) to find how many moles of the other reagent are needed • Compare moles needed to moles you have to find which one is limiting

  17. If 2.70mol of C2H4 is reacted with 6.30mol O2, what is the limiting reagent? C2H4 + O2 CO2 + H2O • What is the limiting reagent if 6.0g HCl reacts with 5.0g Mg? Mg + HCl  MgCl2 + H2

  18. Limiting reagents can be used to find out how much product is actually made. • What is the maximum number of grams of Cu2S that can be formed when 80.0 g Cu reacts with 25.0g S? Cu + S  Cu2S • What is the limiting reagent? • Use the limiting reagent to calculate the amount of product

  19. How many grams of water can be produced by the reaction of 2.40mol C2H2 with 7.4mol O2? C2H2 + O2 CO2 + H2O • If 2.7mol C2H4 is reacted with 6.3mol O2, how many moles of water are produced? C2H4 + O2 CO + H2O

  20. Things happen in lab… • Theoretical yield: the maximum amount of product that could be formed • Actual yield: the amount of product that is actually formed in lab Percent Yield = Actual yield x 100% Theoretical yield

  21. What is the percent yield if 13.1g CaO is actually produced when 24.8g CaCO3 is heated? CaCO3 CaO + CO2

More Related