safety Always: Wear goggles Wear lab gear Hair up Wear closed shoes NO playing Monitor experiments Check before turning the gas on Call the teacher if there is a problem – IMMEDIATELY Know where safety gear is Rinse off chemical simmediatley Follow all directions safety http://elearning.flinnsci.com/StandalonePlayer.aspx?vid=Whoosh Bottle Safety.flv

Chemical reactions

chemical reaction reactant product physical change chemical change chemical equation mitochondria chloroplast exothermic endothermic You should be able to identify and describe the following: a chemical reaction the difference between a chemical and physical change the components of a chemical equation exothermic versus endothermic reactions Vocabulary & Goal

Chemical versus physical changes Chemical changes Physical changes During this change the substance made is chemically different from what you started with The change cannot be reversed Clues: Smoke Sound Color change Gas is produced There is a change in size or shape change in state (solid, liquid, or gas) The change can be reversed Chemical versus physical changes

Your turn: physical or chemical changes explain your reasoning. Glass breaking Hammering wood together to make a house Spoiling food (what happens when you have milk for too long) Melting butter Burning toast (bread in the toaster for too long) Cutting grass Digestion of food Mixing salt and water

occurs when ingredients combine, interact, are rearranged, and new substances are made. More scientifically: in a chemical reaction you combine reactants (the original ingredients) to create a final product (what you get at the end of the chemical reaction) A chemical change has occurred. Chemical reaction

Chemical equation describes the reactants and products of a chemical reaction Reactants -the chemicals you start with & are written on the left side of the chemical equation Products - the chemicals that are made & are written on the right side of the chemical equation

Ingredients Reactants and products can be elements, compounds, or mixtures. An element is an atom. More on these later. A compound is made of more than one element bonded together. More on these later. A mixture is made of elements and/or compounds stirred together but not bonded

Therm – means heat or energy Endothermic Exothermic Exo- means out or to exit In an exothermic reaction – energy is released. Temperature of the surroundings increases (feels hot) Light may be emitted Why? When atoms bond together they release heat Endo –means inside or to enter In an endothermic reaction – more energy is absorbed than released Temperature of the surroundings decreases (feels cold) Why? Atoms need to absorb heat to break their bonds http://www.youtube.com/watch?v=p-27I_osoaw

Endothermic or Exothermic? Why? Your turn – identify each as endothermic or exothermic reaction and explain your reasoning Activity Endothermic or Exothermic? Why? making ice cubes *   melting ice cubes * cooking an egg burning wood Liquid water turning into steam (evaporation) * rusting iron * = not a chemical reaction

Pre-Lab Information How to measure pH to see if a liquid is an acid or alkaline Use a glass rod to take out a small sample of the liquid Transfer the sample to the litmus paper Wait 30 seconds Compare color to sheet Record pH and whether the liquid is acid (pH < 7), neutral (pH = 7), or alkaline (pH >7) Safety Goggles, lab coat, and hair up

Identity the Reactants Chemical Equation:   Identity the Reactants Identity the Products Elements, compounds, or mixtures? Color of litmus paper Acid or alkaline? Brief description of the method Observations: sight, smell, feel, etc. Was this an exothermic or endothermic reaction? How did you know this? Did a physical or chemical change occur during this reaction? How do you know?

HW: read pages 7-8 in packet describing common chemical reactions and balancing equations