1 Chapter 4 Chemical Equations and Stoichiometry

2 Chemical Equations Show Substances being reacted – on the ____ of the arrow Substances being produced (products)- on the _____ of the arrow States of the substances – (s), (l), (g), (aq) ___________ used – (sometimes listed above or below the yield arrow), or _____  A balanced equation demonstrates the Law of ____________________________ (the mass (or moles) of substances reacted = the mass (or moles) of products produced)

3 Balancing Equations Examples follow:

4 Types of Equations - Review __________________ (aka synthesis) Decomposition Single Displacement (aka single replacement) Double Displacement (aka double replacement) Some acid/ base and ionic equations are also called “__________ rxns” - Acid / Base neutralization - Combustion - ionic (_____________ reactions) Three are two Power Point lessons on the web site to review types of Chemical Equations

5 Stoichiometry Calculating how much product can be produced is called _________________. After the theoretical yield is calculated, the experiment is carried out in the lab. The “________________” is what is obtained when the experiment is actually carried out. The “___________” is [Actual / theoretical] x 100. A balanced chemical equation is needed in order to complete any stoichiometry problem. Examples:

6 Oxygen can be prepared on a small scale by the decomposition of KClO 3. Write the balanced reaction and calculate the theoretical yield, in moles, of O 2 if moles of KClO 3 are decomposed. If moles of O 2 are actually produced in the lab, what is the percent yield?

7 What mass of O 2 is required to completely combust 454 grams of propane? What masses of CO 2 and H 2 O are produced?

8 Limiting Reagent (or Reactant) You recognize these because there will be ___ _____ _________ __ _________. Example; If grams of TiCl 4 are reacted with 500. Grams of water, how many grams of TiO 2 will be produced? (The other product is HCl). How many grams of HCl will be produced? What mass of excess reactant remains after the reaction?

9 Quantitative analysis of a sample From page 135 of your text:

10 Determining the Empirical Formula by Use of Combustion A g sample of unknown containing C and H is burned in air to give g of CO 2 and g of H 2 O. In a separate experiment, the molar mass for the compound was found to be 114 g/ mol. Determine the empirical and molecular formulas. Page 139 in text

11 A g sample of an alcohol composed of C, H, and O was burned to produce g CO 2 and g H 2 O. Determine the empirical formula of the alcohol.