Download Predicting Products online assistance #3

PREDICTING PRODUCTS RE-TEACHING WORK
Most chemical reactions can be classified into four major types:
1. synthesis - two reactants combine to form one product
2. decomposition - one reactant decomposes, or breaks apart, into two or more products.
3. single replacement - an element replaces another in a compound.
4. double replacement - the elements in two compounds switch partners to form two new compounds.
Writing Balanced Equations
A chemical reaction is the process by which one or more substances are changed into one or more different
substances. A chemical reaction may be represented by a chemical equation. A correct chemical equation shows
what changes take place. It also shows the relative amounts of the various elements and compounds that take part in
these changes. For example, let’s write a balanced chemical equation for the following reaction:
iron metal reacts with oxygen to form iron (III) oxide.
STEP 1: Determine exactly which are the reactants and the products.
iron metal reacts with oxygen to form iron (III) oxide
STEP 2: Write the correct formulas for each of the reactants and products then assemble the equation. the reactants
are written first, to the left of the arrow. The products are written to the right of the arrow. Remember there are
seven diatomic elements. Each compound must be neutral. The sum of the charges must equal zero.
iron metal reacts with oxygen to form iron (III) oxide
Fe + O2 Fe2O3
STEP 3 Balance the equation. The same number of atoms of each element must be on both sides of the equation. To
balance an equation, change only the coefficients. Never change the subscripts.
4Fe + 3O2  2Fe2O3
Predicting Products of Chemical Reactions
The products of a chemical reaction may often be predicted by applying known facts about common reaction types.
While there are hundreds of different kinds of chemical reactions, we will only consider four general types: single
displacement, double displacement, decomposition, and synthesis.
A single displacement reaction occurs when one element displaces another in a compound. The general form of a
single displacement reaction is element + compound  element + compound
Zn + 2HCl  H2 + ZnCl2
A double displacement reaction occurs when the positive and negative ions of the two reactants are interchanged.
The general form of a double displacement reaction is
compound AB + compound CD  compound AD + compound CB
FeS + 2HCl  FeCl2 + H2S
A decomposition reaction occurs when energy in the form of heat, light, electricity, or mechanical shock is supplied.
A compound may decompose to form simpler compounds and/or elements. The general form of a decomposition
reaction is compound two or more substances.
There are six general types of decomposition reactions. You will need to know all six different types. Consider two
types today.
1. Most metallic oxides are stable, but a few decompose when heated to form the metal and oxygen gas.
Example: 2HgO  2Hg + O2.
Some compounds can be decomposed by electricity into their elements. Example: 2NaCl  2Na + Cl2
A synthesis reaction occurs when two or more simple substances (elements or compounds) are combined to form
one new and more complex substance. The general form of a synthesis reaction is element or compound + element
or compound compound
2Mg + O2  2MgO
ONLINE ASSISTANCE:
http://www.chem.vt.edu/RVGS/ACT/notes/Types_of_Equations.html
http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Equations.html
http://employees.csbsju.edu/HJAKUBOWSKI/classes/ch123/Chem%20Reactions/hintsmistakesrx.htm
http://misterguch.brinkster.net/6typesofchemicalrxn.html (from www.chemfiesta.com)
http://web.fccj.org/~ksanchez/2045/wksheet/Reactions.htm
http://pages.towson.edu/ladon/react.html
Directions: Predict the products and write a balance equation for each of the following reactions.
Synthesis reactions
1. calcium reacts with oxygen
2. sulfur reacts with oxygen
3. carbon reacts with excess oxygen
4. aluminum reacts with nitrogen
5. magnesium reacts with sulfur
6. sodium reacts with oxygen
7. rubidium reacts with excess oxygen
Decomposition reactions
8. silver oxide is heated
9. water is decomposed by electricity
Single replacement reactions
10. zinc metal reacts with copper (II) nitrate
11. sodium iodide reacts with chlorine gas
12. potassium metal reacts with water.
13. iron reacts with copper (II) chloride.
14. Bromine reacts with sodium chloride.
Double replacement reactions
15. aluminum sulfate reacts with calcium phosphate
16. magnesium chloride reacts with silver nitrate
17. copper (II) oxide reacts with sulfuric acid.
18. silver nitrate reacts with hydrogen sulfide
19. lead (II) nitrate reacts with potassium chromate