Science 10 Chapter 4.3 Balancing Chemical Equations
Today
Learning check Review chemical compounds and formulas Chemical Reactions!!!
1. Silver chloride__________2. Sulphur dioxide__________3. Lead (II) acetate decahydrate_______________4. Silver dichromate__________5. Silicon tetraflouride__________6. Ammonium phosphate __________7. Copper (I) iodide__________8. Iron (II) fluoride nonahydrate_____________9. Zinc hydrogen sulphite______________10. Manganese (IV) monohydrogen phosphate
trihydrate ________________
Name into Formula
Formula into Name
1. NI3 _______________________________
2. Ca(OH)2 _______________________________
3. Fe2(SO4)3.H2O _______________________________
4. (NH4)2C2O4 _______________________________
5. Co3(PO4)2.8H2O_______________________________
6. H3PO4 _______________________________
7. HClO2 _______________________________
8. N3O _______________________________
9. HI _______________________________10. Mg3P2 _______________________________
Chemical Changes
• Nothing is created or destroyed, only rearranged• Reactants = products• 200 yrs ago John Dalton realized
atoms rearrange • # of each atom in reactants = # of each atom in products
The LAW: Conservation of mass• Antoine and Marie-Anne Lavoisier in the 1700’s
• Atoms are neither created or destroyed in chemical reactions
• Mass reactants = mass products
Indicators of chemical change
1. Colour changes2. Temperature changes3. A gas is produced4. A precipitate (solid form
Chemical Reactions
• Occur when new substances are createdreactants products
Can be written as:• A word equation:
nitrogen monoxide + oxygen nitrogen dioxide• A symbolic equation:
2NO(g) + O2(g) 2NO2(g)
Word equations (the simplest)
Potassium metal + oxygen gas potassium oxide
Provides limited information
Skeletal Equations (Symbolic)
• Show formulas of compounds/elements, but not quantities of atoms
e.g.,K + O2 K2O
Symbolic Equations
2NO(g) + O2(g) 2NO2(g)
Coefficients – indicate ratio of cmpdsState of matter – dissolved in water/aqueous (aq), solid (s), liquid (l), or gas (g)
Balanced chemical equation• Shows all atoms and their quantities• Number of each atom should be equal on both
sides of the reaction arrow• Always use smallest whole-number ratio• To balance, change coefficients, never subscripts
e.g., 4K + O2 2K2O
HgO Hg + O2
Helpful hints
1. Balance metals first2. Count polyatomic groups as 1 atom3. Balance oxygen atoms last4. Odd/even problem? Double it!
____Mg + ____HCl → ____MgCl2 + ____H2
____H2 + ____ N2 → ____ NH3
____ Fe + ____ Br2 → ____ FeBr3
TRY THESE!____Sn(NO 2)4 ___K3PO4 → ___KNO2 ___Sn3(PO4)4
____P4 + ____I2 → ____PI3
____Al + ____O2 → ____Al2O3
Today Learning check Review chemical compounds and formulas Chemical Reactions
#X#(s) A B Due tomorrow: workbook pages 71 and 73 Due Monday: workbook pages 77, (78-79 even #’s), 80