150 likes | 235 Views
Chemical Reactions. Changing Matter. What is a Chemical Reaction?. Also known as a chemical change. At the end of a chemical reaction you end up with a different substance than what you started with.
E N D
Chemical Reactions Changing Matter
What is a Chemical Reaction? Also known as a chemical change. At the end of a chemical reaction you end up with a different substance than what you started with. Take a moment with your table partner to come up with two examples of chemical change and one physical change.
Parts of a chemical reaction Reactants- your starting compounds, molecules or elements Products- the resulting compounds molecules or elements Reactant 1 + Reactant 2 = Product 1 + Product 2
Word equations • Word equations give you the name of reactants and products. • Aluminum + Bromine Aluminum Bromide • Which reads aluminum and bromine react to form aluminum bromide • Carbon + Sulfur Carbon Disulfide • How would you read this one?
Skeleton Equations give you the chemical formula of the reactants and products Al(s) + Br2(l) AlBr2(s) The small letter in parentheses tells you what state the elements or compounds are in. Skeletal equations give the same amount of information as word equations, but the skeletal equations show you more at a glance.
Comparing the two • Aluminum + Bromine Aluminum Bromide • Al(s) + Br2(l) AlBr2(s) • What is the major difference between the two? • The skeletal equations tells you that you need 2 bromine to every one aluminum • Write the Skeleton equations for: • Carbon + Sulfur Carbon Disulfide • Lithium + Fluorine Lithium Fluoride
Chemical Equations A statement that uses chemical formulas to show the identities and relative amounts of the substances in a chemical reaction.
Parts of CE • Coefficient- multiplies everything behind it until the next mathematical symbol • Element, compound, or molecule- the chemical formula for the substance • Subscripts- multiply the element directly in front of it • State of matter- Lets you know what state it is currently in. • Gas- (g), Liquid (l), Solid (s), Aqueous (aq)
Balancing Equations Conservation of states of matter states that matter is neither created or destroyed so The # atoms on one side = # atoms on the other side How many atoms total are on each side?
How to balance Start by finding out how many atoms there are for each element on both sides of the equation. Then start with any that are odd numbers- odd on one side even on the other. They will only line up so many ways so they need to be taken care of first Then start going back and forth. Remember that a change on one side will effect the other. Remember to reduce the coefficients to the lowest possible ration Write out and balance the equations for problems 4, 5, and 6 on page 287
Types of chemical reactions • Synthesis reaction • Two more more reactants come to form one product. • A + B AB • Iron + Oxygen gas iron oxide (rust) • Na + Cl NaCl
Combustion reactions A specific type of synthesis reaction that has a release of energy in the form of heat and light. C(s) + O2(g) CO2(g) 2H2(g) + O2(g) 2H2O
Decomposition Reactions One single reactant breaks down into two products AB A + B H2O2 H2O + O2 Balance the equation 2H2O2 2H2O + O2
Replacement Reactions This type is a swap of sorts Single replacement reactions move one piece AX + B A + BX 2H2O + 2Li H2 + 2LiOH CuSO4 + Fe FeSO4 + Cu
Double replacement reactions AX + BZ AZ + BX Acid + Base salt + water HCL + NaOH ? + ? HCL + NaOH NaCl+ H2O