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Chemical Reactions

Chemical Reactions. G.Burgess 2006. Chemical Reactions. Occur when atoms of substances join other atoms of other substances to form different chemical materials There are several types of chemical reactions Chemists show chemical reactions symbolically as chemical equations.

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Chemical Reactions

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  1. Chemical Reactions G.Burgess 2006

  2. Chemical Reactions • Occur when atoms of substances join other atoms of other substances to form different chemical materials • There are several types of chemical reactions • Chemists show chemical reactions symbolically as chemical equations

  3. Chemical Equations Products Reactants NaOH(aq)+ HCl(aq) NaCl(aq) + H2O(l) Molecular formula of compound State (aq) = aqueous/ in water (l) = liquid **the ‘+’’s means “reacts with” **the arrow between the reactants and products means “to give”.

  4. Types of chemical reactions • Formation(synthesis): when two pure substances combine to make a new substance ie. 2H2 + O2 2H2O 2. Decomposition: when a compound breaks up into its individual parts. ie. 2H2O 2H2 + O2

  5. Types of chemical reactions • Single displacement: when one element is removed from a molecule and replaced by another element. ie. 2Fe + 6HCl 2FeCl3 + 3H2

  6. Types of chemical reactions • Double displacement: When 2 molecules switch elements. AgNO3 + HClAgCl + HNO3

  7. Review • Fe + S FeS • 2 Mg + O2 2 MgO • Na2O + H2O 2 NaOH • CuCO3 CuO + CO2 • Fe + H2SO4 FeSO4 + H2 • AgNO3 + NaCl AgCl + HNO3

  8. Answers to review • Synthesis • Synthesis • Synthesis • Decomposition • Single Displacement • Double displacement

  9. Rules of chemical reactions • Law of conservation of matter: • The number of atoms of each element produced is the same as the number of atoms in the reactants. ie. H2 + O2 H2O 2H2 + O2 2H2O Creating a balanced equation helps demonstrate this law.

  10. Balancing Chemical Equations • All chemical equations must demonstrate the Law of conservation of matter. • Begin by balancing the metals • Then Poly atomic ions • Then non-metals • Then hydrogen • Lastly, balance oxygen.

  11. Balancing Chemical Equations Example: Al + O2 Al2O3 • Al on the left = 1; Al on the right = 2. Put a 2 in front of the Al on the left. 2Al + O2 Al2O3 2. O on the left = 2; O on the right = 3. Put a 3 in front of O on the left and 2 in front of Al on the right. 2Al + 3O22Al2O3 NOTICE: The Al’s do not match. To balance the Al’s use a multiple of all three numbers (2Al=2; 2Al2=4) Since Al = Al1 and 1*4 = 4. then the balanced formula is… 4Al + 3O22Al2O3 **Now we have 4Al’s and 6O’s on each side.

  12. Review • S + H2SO4 SO2 + H2 • NaCl + BeF2 NaF + BeCl2 3. Ca(OH)2(aq) + HCl(aq) CaCl2(aq) + H2O(l) 4. CH4 + O2 CO2 + H2O 5. Mg + Mn2O3 MgO + Mn

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