30
CHEMICAL EQUATIONS & REACTION STOICHIOMETRY Chapter 3

CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

  • Upload
    larue

  • View
    69

  • Download
    0

Embed Size (px)

DESCRIPTION

CHEMICAL EQUATIONS & REACTION STOICHIOMETRY. Chapter 3. Chemical Equations. symbolic representation of a chemical reaction that shows: reactants on left side of reaction products on right side of equation relative amounts of each with stoichiometric coefficients - PowerPoint PPT Presentation

Citation preview

Page 1: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Chapter 3

Page 2: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

symbolic representation of a chemical reaction that shows:◦ reactants on left side of reaction◦ products on right side of equation◦ relative amounts of each with stoichiometric

coefficients◦ attempt to show on paper what is happening at

the molecular level

Chemical Equations

Page 3: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Matter is not created or destroyed, there is no detectable change in quantity of matter in an ordinary chemical reaction

discovered by Lavoisier balance chemical reactions using coefficients balancing equations is a skill acquired

only with lots of practice propane,C3H8, burns in oxygen to give carbon

dioxide and waterC3H8 + 5 O2 ® 3 CO2 + 4 H2Othere are equal numbers of atoms of each element on

both sides of equation

Law of Conservation of Matter

Page 4: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 1) How many CO molecules are required to react with 27 formula units of Fe2O3 to make iron and carbon dioxide

Calculations Based on Chemical Equations

Page 5: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 2) What mass of CO is required to react with 140.0 g of iron (III) oxide?

Page 6: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 3) How many pounds of carbon monoxide would react with 128 pounds of iron (III) oxide?

Page 7: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Most experiments do not have the exact amounts needed to completely react. LR helps us decide which reactant is in excess (the one we have plenty of) and which reactant is limiting (the one that will determine the outcome of the reaction)

~ If a box has 87 bolts, 113 washers and 99 nuts, how many sets consisting of one bolt, two washers and one nut can you make?

Limiting Reactant (Reagent) Concept

Page 8: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 4) What is the maximum mass of sulfur dioxide that can be produced by the reaction of 95.6 g of carbon disulfide with 111 g of oxygen? (combustion rxn) How much of the excess chemical remains?

Page 9: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Most rxns in real life do not go to completion. A few reasons why ◦ Reactants did not react 100% to give the products◦ Side reactions can occur to form undesirable

products as well as the wanted products theoretical yield is what we have been

calculating on paper actual yield is what you have made in the

lab

Percent Yields from Reactions

%100yield ltheoretica

yield actual = yield %

Page 10: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex 5) A 10.0 g sample of ethanol, C2H5OH, was boiled with excess acetic acid, CH3COOH, to produce 15.0 g of ethyl acetate, CH3COOC2H5. What is the percent yield? (The other product is H2O)

Page 11: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex 6) Using the percent yield from Ex. 5, how much C2H5OH, is needed to give a yield of 45.0 g of CH3COOC2H5?

Page 12: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Sequential ~ multiple steps are needed for a rxn to go to completion

HNO3 Sn C6H6 C6H5NO2 C6H5NH2

H2SO4 Conc HCl

Sequential Reactions

Page 13: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 7) Starting with 100. g of benzene (C6H6), calculate the theoretical yield of nitrobenzene (C6H5NO2) and of aniline (C6H5NH2). (1 to 1 mole ratios)

Page 14: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 8) If 46.7 g of aniline is prepared from 100. g of benzene, what is the percentage yield?

Page 15: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

solution – a homogeneous mixture of 2 or more substances. Usually one substance is dissolved in another

solute – what gets dissolved solvent – what does the dissolving (water is the

universal solvent) concentration - amount of solute dissolved in a

solvent

Mass of solution = mass of solute + mass of solvent

% by mass of solute = mass of solute x 100% mass of solution

Concentration of Solutions

Page 16: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 9) Calculate the mass of potassium nitrate required to make 277 g of solution that is 20.0% KNO3 by mass. What is the mass of water in the solution?

Page 17: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 10) What volume of 24.5% lead(II) nitrate solutions contains 40.0g of lead(II) nitrate? The density of the solution is 1.25 g/mL

Page 18: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

molarity = mol solute/L of solution = M

Ex. 11) Calculate the molarity of a solution that contains 12.8 g of sulfuric acid in 1.70 L of solution.

Molarity (Molar Concentration)

Page 19: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 12) Determine the mass of calcium nitrate required to prepare 3.55 L of 0.822 M solution.

Page 20: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 13) The specific gravity of concentrated HCl is 1.185 and it is 36.31% w/w HCl. What is its molarity? (What is the pH of the soln?)

Page 21: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Dilution of Solutions number of moles of

solute remains constant M1V1 = M2V2 works

because # of moles is constant

If 10.0 mL of 12 M HCl is added to enough water to give 100. mL of solution, what is concentration of the new solution?

Page 22: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 14) What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.44 M sulfuric acid solution?

M1V1 = M2V2 n1 n2

Page 23: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Combine the ideas of molarity and stoichiometry

Ex. 15) What volume of 0.500 M BaCl2 is required to completely react with 4.32 g of Na2SO4?

Solution Stoichiometry

Page 24: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 16) a) What volume of 0.220 M NaOH will react with 50.0 mL 0f 0.220 M aluminum nitrate? b) What mass of aluminum hydroxide precipitates?

Page 25: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Titrations method of

determining the concentration of solutions once the concentration of a standard solution is known

requires special glassware

buret, pipet, flasks, and an indicator

Page 26: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Ex. 17) What is the molarity of a barium hydroxide solution if 44.4 mL of 0.103 M HCl is required to react with 38.8 mL of the barium hydroxide solution?

Page 27: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

In the lab, acid-base rxns are carried out as a titration:

◦ Standard solution: a soln of known concentration

◦ Standardization: process by which the conc. of a standard soln is determined.

◦ Equivalence point: point in a titration at which chemically equivalent amounts of reactants have reacted

◦ Endpoint: point in a titration where the indicator changes color and the titration is stopped.

Page 28: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Each diagram (A-P) shows a sample of a substance as viewed at the atomic level. Characterize the contents of each container in terms of the following categories:I. Homogeneous mixture, heterogeneous mixture or pure substanceII. Element(s), compound(s) or bothIII. Solid, liquid, gas or combination of phases

http://intro.chem.okstate.edu/1314F00/Lecture/Chapter1/Atomic.html

Atomic level practice

Page 29: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Nylon is made by the reaction of hexamethylene diammine, molar mass of 116.208, with adipic acid, molar mass of 146.142, in a 1 to 1 mole ratio to produce 1 mole of nylon, molar mass of 212.293. On a daily basis, a DuPont factory makes 1.5 million pounds of nylon. How many pounds of hexamethylene diamine and adipic acid must they have available in the plant each day?

Page 30: CHEMICAL EQUATIONS & REACTION STOICHIOMETRY

Manganese dioxide, potassium hydroxide and oxygen react to produce potassium permanganate and water. A mixture of 272.9 g of manganese dioxide, 2.660 L of 0.2500 M potassium hydroxide, and 41.92 g of oxygen gas are allowed to react. After the reaction is finished, 247.6 g of potassium permanganate is separated from the reaction mixture. What is the percent yield of this reaction?