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Balancing Chemical Equations

Balancing Chemical Equations. Left of the staircase is positively charged. Right of the staircase is negatively charged. Balancing Charges. When a metal and a non-metal are combined an ionic compound is formed. Ex.  NaCl (s )

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Balancing Chemical Equations

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  1. Balancing Chemical Equations

  2. Left of the staircase is positively charged. Right of the staircase is negatively charged. Balancing Charges

  3. When a metal and a non-metal are combined an ionic compound is formed. Ex. NaCl(s) Sodium has a charge of 1+ while chlorine is 1-. The two combine with no extra atoms needed. However the compound aluminum fluoride is different. Ex. AlF3 (S) Aluminum has a charge of 3+ and fluoride has a charge of 1-. Three fluorine atoms are needed to balance the electron charges. Ionic Compounds

  4. Balancing Simple Equations In order to balance a simple equation you need to make sure all the charges in the compounds are balanced. Ex. _Al + _H2SO4  _Al2(SO4)3 + _H2

  5. Special Ten • Keep in mind the “special ten”. • When on their own, such as the last hydrogen in the previous equation, the special ten come in specific quantities. • They are as follows: • H2 • C2 • N2 • O2 • F2 • Cl2 • Br2 • At2 • S8 • P4

  6. Multiple Charges • Some metals have multiple charges. • When in doubt use the most common ion charge. This is first one. • Questions will indicate which charge to use with roman numerals. • Ex. Balance iron (III) chlorine. • FeCl3(S) • If iron is has a charge of 3+ and chlorine 1-, three chlorine atoms are needed to balance the charges.

  7. Hydrates • A hydrate is when a certain amount of water is attached to a compound. • Ex. sodium chloride heptahydrate OR sodium chloride-7-water • When written hydrates look as follows. • Ex. NaCl 7H2O • A small filled in dot separates the water molecules.

  8. Naming Ionic Compounds • The non-metallic part of the compound has the only change in its name. Change the ending of the element to “ide”. • Ex. sodium chloride • iron (III) sulfide

  9. Polyatomic Ions • Watch out for polyatomic ions. • They are negatively charged compounds that mix with metals to form ionic compounds. • Ex. sodium phosphate • Na3(PO4)(aq) • To name these ionic compounds simply look on your table of elements for the polyatomic ions for the names. Then put the metal and polyatomic together.

  10. Balancing Simple Equations • _Al + _H2SO4 _Al2(SO4)3 + _H2 • 2 Al + 3 H2SO4  _Al2(SO4)3+ 3 H2 • From left to right balance the equation so the number of atoms of each compound account for each other.

  11. Word Problems • When given a word problem write out the compounds in a line and balance accordingly. • There are different types of equations and different ways to balance them. • Determine the type and proceed to solve from there.

  12. Formation • Ex. Sodium and chlorine react to produce: • _Na + _Cl _NaCl • Simply combine the elements and balance the charges like so. • Ex. Aluminum and chlorine react to produce: • _Al + _Cl  _AlCl3 • _Al + 3Cl  _AlCl3 • Since the initial charges create an off balance equation, more chlorine atoms are needed.

  13. Decomposition • Ex. Sodium chloride breaks down into its elements: • _NaCl  _Na + _Cl • This is the opposite of a formation reaction. • Ex. Aluminum chloride breaks down into is elements: • _AlCl3  _Al + _Cl • _AlCl3  _Al + 3Cl • More chlorine atoms are needed in the equation when properly balanced.

  14. Single Replacement Ex. sodium is added to lithium sulfide. _Na + _Li2(SO4) _Li + _Na2(SO4) 2Na + _Li2(SO4) 2Li + _Na2(SO4) When balancing this equation replace the metals and balance normally. If a non-metal was added, replace the non-metals.

  15. Double Replacement • Ex. sodium chloride is mixed with lithium fluoride. • _NaCl + _LiF  _NaF + _LiCl • When balancing this equation move • Since all the charges are balanced this equation is easy, but keep in mind all the possible factors. • Special Ten • Multiple Charges • Polyatomics

  16. Combustion Ex. Methane is burned in the presence of oxygen. _CH4 + _O2  _CO2 + _H2O _CH4 + 2O2  _CO2 + 2H2O When balancing combustion carbon dioxide and water are always formed. Balance alphabetically.

  17. Combustion Part 2 Some problems will require a different method: Ex. _C8H18 + _O2  _CO2 + _H2O When balancing you will notice the oxygens will not balance properly. Simply double your existing numbers and then balance. _C8H18 + _O2  8CO2 + 9H2O ? 25 O’s? 2C8H18 + 25O2  16CO2 + 18H2O

  18. Molecular Compounds • A molecular compound is formed when a non-metal and non-metal combine. • Ex. Carbon Dioxide (CO2) • Question will provide proper amounts of each element but to name you need to know Latin prefixes. • Mono • Di • Tri • Tetra • Penta • Hexa • Hepta • Otca • Nona • Deca

  19. Molecular Compounds Part 2 • Add the prefix to your compound according to the amounts of each element. • Ex. P4O3 • Tetraphosphorus trioxide • Remember your “ide’s” at the end and watch out for polyatomic. • Ex. PO4 • Phosphate • NOT monophosphprus tetraoxide

  20. The End

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