Chapter 3 Chemical Reactions

Physical Properties of Matter Physical Property - any property of matter that can be observed or measured without changing the identity of the matter Examples: color shape taste state/phase density D = m V

Physical Change ( Reaction) Physical Change – a change that affects one or more physical properties of a substance * a change in shape, size, color, or state a change without a change in chemical composition a change that is reversible Examples: tearing paper cutting your hair change in state ex. Solid to liquid leaves changing color

Chemical Properties of Matter Chemical Property - any property of matter that describes a substance based on its ability to change into a new substance that has different properties Examples flammability reactivity with vinegar reactivity with oxygen Iron + Oxygen  Iron oxide (rust) 2Fe + 3O2  Fe2O3

Chemical Change (Reaction) Chemical Change -a change in which a substance becomes another substance having different properties a change that is not reversible using ordinary physical means Changes that usually cause heat, sound, light, odor, fizzing/foaming, color changes You usually need more than one of the above characteristics to be considered a chemical change! Examples: combining sulfuric acid and sugar burning a piece of wood soured milk

Signs of a Chemical Reaction fire Bubbles/fizzing color changes rust precipitate A solid that is produced as a result of a chemical reaction in a solution, the solid is called the precipitate.

Chemical or Physical Property? Paper is white Boiling point of H2O is 100oC Zinc reacts with hydrochloric acid and creates hydrogen gas Nitrogen does not burn Sulfur smells like rotten eggs Physical Property Physical Property Chemical Property Chemical Property Physical Property

Comparing Physical and Chemical Properties Substance/Matter Physical Property Chemical Property Helium Less dense than air Nonflammable Wood Grainy texture Flammable Baking soda White powder Reacts with vinegar to produce bubbles Powdered sugar Does not react with vinegar Rubbing alcohol Clear liquid Red food coloring Red color Reacts with bleach and loses color Iron Malleable Reacts with oxygen

Chemical or Physical Change? Bending a Paper Clip Baking a cake The phase change of carbon dioxide Crushing an aluminum can Vinegar and baking soda combining to create salt and water Physical Change Chemical Change Physical Change Physical Change Chemical Change

Is evaporation a physical change or a chemical reaction? 7 Is evaporation a physical change or a chemical reaction? [This object is a pull 

tab] Answer A A Physical Change B Chemical Reaction C May be either

Is dissolving in water a physical change or a chemical reaction? 8 Is dissolving in water a physical change or a chemical reaction? [This object is a pull 

tab] Answer A A Physical Change B Chemical Reaction C May be either

Is burning paper a physical change or a chemical reaction? 9 Is burning paper a physical change or a chemical reaction? [This object is a pull 

tab] Answer B A Physical Change B Chemical Reaction C May be either

Is baking a cake a physical change or a chemical reaction? 10 Is baking a cake a physical change or a chemical reaction? [This object is a pull 

tab] Answer B A Physical Change B Chemical Reaction C May be either

Are smoke and flame signs of a physical change or a chemical reaction? 11 Are smoke and flame signs of a physical change or a chemical reaction? [This object is a pull 

tab] Answer B A Physical Change B Chemical Reaction C May be either

Are bubbles a sign of a physical change or a chemical reaction? 12 Are bubbles a sign of a physical change or a chemical reaction? [This object is a pull 
tab] Answer C Bubbles can form when something evaporates, like boiling water. Bubbles can form when chemicals react like vinegar and baking soda. A Physical Change B Chemical Reaction C May be either