CHEMICAL REACTIONS

Chemical Reactions INVESTIGATION ONE

 Chemical compounds are formed when two or more elements combine.  H ₂ + O  H₂O (water)  Na + Cl  NaCl ( Sodium Chloride – Salt) CHEMICAL COMPOUNDS

 Elements are held together by chemical bonds.  Two Types of Chemical Bonds  Ionic bonds are formed by positive and negative ions that are attracted together resulting in the loss or gain of electrons  Covalent bonds are formed between Carbon atoms and another element and no electrons are gained or lost. CHEMICAL BONDS

 When two or more compounds interact a chemical reaction can occur  The chemical compounds that interact are called reactants  The substances that form from their interactions are called products CHEMICAL REACTIONS

 Reactants and Products can be written in the form of an equation called a chemical formula  Reactants and Products are separated by (  ) (yield)  Reactant + Reactant  (yield) Product (s)  NH ₄ OH + HCL  H ₂ O + NH ₄ CL + Heat  Ammonium hydroxide + hydrochloric acid yields water + ammonium chloride+ heat CHEMICAL FORMULAS

 Single elements, new compounds, and heat all can be products of a chemical reaction  Measuring the starting temp ending temp determines the amount of heat and products produced PRODUCTS

 In a chemical reaction, as the amount of reactants increases the amount of the products produced also increases. RELATIONSHIP BETWEEN REACTANTS AND PRODUCTS

Chemical Reactions INVESTIGATION TWO

 During a chemical reaction the bonds that hold chemical compounds together break and reform in different arrangements when they interact to form products BONDS IN CHEMICAL REACTIONS

 When all of the reactants are used in a chemical reaction they no longer are present in their original form  All of the atoms from the reactants are found in the products  The atoms are converted from a reactant to a product REACTANTS IN CHEMICAL REACTIONS

 The converting of reactants to products is referred to as the Law of Conservation of Matter  Matter is not created or destroyed just simply changes (converted) form LAW OF CONSERVATION OF MATTER

 Sometimes some reactants are present in higher amount than others  The one that has a lesser amount is completely used up in the reaction  At this point the chemical reaction stops and the other reactant remains unreacted  Mg + 2HCl  MgCl ₂ + H ₂ REACTANTS

 Reactants must be present in the reaction in equivalent amounts to produce the maximum amount of all products AMOUNT OF REACTANT AFFECTING THE AMOUNT OF PRODUCTS

 No matter is lost from a chemical reaction even is the reactants are present in amounts that are not equivalent.  Every atom of every reactant can be found in either the products or in the reactants that are not consumed LAW OF CONSERVATION OF MATTER AND CHEMICAL REACTIONS

INVESTIGATION THREE

 As the reactants interact they are consumed at the same time that the products are formed.  Since the products come from the reactants and the rate at which the reactants are consumed is equal to the rate that the products are formed. CHEMICAL REACTIONS

 The rate at which a reactant disappears or a product is produced can be measured to get the rate of the reaction  Scientist can measure the absorbance of a specific wavelength to determine the rate of the reaction  Spectrophotometer measures the absorbance of different wavelengths  Wavelength is measured in nanometers RATE OF A REACTION

 In order to affect the rate of a reaction a catalyst can be added  A catalyst is neither a reactant nor a product because it is not produced or consumed.  CH₃COCH₃ + I₂  (HCL)  CH₃COCH₂I + HI  HCL = catalyst SPEEDING UP A REACTION

 As the amount of reactant increases, the rate of the reaction increases.  As the rate increases, this can be measured as an increase in the rate of disappearance if the reactants and an increase in the production of products.  Therefore the more reactants added to a reaction, the more products that will be produced. RELATIONSHIP BETWEEN REACTANTS, PRODUCTS, AND THE RATE OF THE REACTION