Chemical Reactions

Homework Read pages: 61-63 Worksheet: Word Equations and Reactions 2

Describing Chemical Change In a chemical reaction, one or more substances (reactants) change into one or more different substances (products). Reactants Products Chemical reactions involve chemical changes.

Describing chemical change Reactants change into products Bonds are broken Atoms re-arrange New bonds are formed Atoms themselves are neither created nor destroyed!

Describing Chemical Change What happens when you combine baking soda and vinegar ? describe some of the changes. In aqueous solution, acetic acid reacts with sodium bicarbonate to produce sodium acetate, carbon dioxide and water.

Describing Chemical Change sodium bicarbonate + aqueous acetic acid sodium acetate + carbon dioxide water

Separates two or more reactants or products  Symbol Explanation + Separates two or more reactants or products  Yields - separates reactants from products →;←;↔ Reversible reaction (s); (l); (g) solid, liquid or gas (aq) Aqueous solution – a substance dissolved in water Heat supplied Platinum used as a catalyst heat → Pt →

Chemical Equations C12H24(s) + O2(g) CO2(g) + H2O(g) The physical state of the substances can be indicated by placing a symbol in parenthesis after the formula C12H24(s) + O2(g) CO2(g) + H2O(g) (s) For solid, (l) for liquid, (g) for gas, and (aq) for an aqueous solution. Heat

Chemical Equations SO2(g) What would the skeleton equation be for the following: Sulfur burns in oxygen to produce sulfur dioxide. S(s) + O2(g) SO2(g) Heat

Chemical Equations H2(g) + KOH(aq) What would the skeleton equation be for the following: When solid potassium is added to water, hydrogen gas and aqueous potassium hydroxide are produced K(s) + H2O(l) H2(g) + KOH(aq)

Homework Read 61-63 Reactions 8 and Balancing Chemical Equations

Balancing Chemical Equations Rules for Balancing Equations Determine the correct formula of all reactants and products Write reactant on the left and products on the right side of the arrow. Count the total number of atoms of each element on each side.

Balancing Chemical Equations Rules for Balancing Equations Balance the elements one at a time by using coefficients – DO NOT CHANGE SUBSCRIPTS Check each atom or polyatomic ion to make sure the equation is balanced Make sure all coefficients are the lowest possible ratio that balances Let’s see how it is done…

Balancing Chemical Equations Balance the following equations: SO2 + O2 SO3 Fe2O3 + H2 Fe + H2O P + O2 P4O10 Al + N2 AlN

Balancing Chemical Equations Balance the following equations: 2SO2 + O2 2SO3 Fe2O3 + 3H2 2Fe + 3H2O 4P + 5O2 P4O10 2Al + N2 2AlN More Practice…