CLASSIFYING CHEMICAL REACTIONS Review of Science 10 (Section 2.5) Pg

Science 10 Review: When counting elements, don’t forget to look at both the subscript and the coefficient. When counting elements, don’t forget to look at both the subscript and the coefficient. For example: For example: PO = has 2 phosphorus atoms and 5 oxygen atoms P 2 O 5 = has 2 phosphorus atoms and 5 oxygen atoms = has 4 phosphorus atoms and 10 oxygen atoms 2P 2 O 5 = has 4 phosphorus atoms and 10 oxygen atoms Because there are 2 molecules (indicated by the coefficient) and 2 atoms in each molecule (indicated by the subscript) – So you multiply!!

Remember: Never change a subscript to balance an equation! Never change a subscript to balance an equation! O 2(g) + H 2(g)  H 2 O (l) Is unbalanced – but you can’t change it the following way! O 2(g) + H 2(g)  H 2 O 2(l) X Make sure the coefficients are the lowest whole-number ratio : Make sure the coefficients are the lowest whole-number ratio : 2O 2(g) + 4H 2(g)  4H 2 O (l) This is a balanced formula but these are not the lowest numbers you could use: O 2(g) + 2H 2(g)  2H 2 O (l) O 2(g) + 2H 2(g)  2H 2 O (l)

1) Write the chemical formulas for the reactants and products including the states Cu (s) + AgNO 3(aq)  Ag (s) + Cu(NO 3 ) 2(aq) Cu (s) + AgNO 3(aq)  Ag (s) + Cu(NO 3 ) 2(aq) 2) Balance the element (atom or ion) present in the greatest number by multiplying by the lowest coefficient possible (NO 3 ) 2(aq) = 2 present (lowest coefficient possible to balance = 2) (NO 3 ) 2(aq) = 2 present (lowest coefficient possible to balance = 2) Cu (s) + 2AgNO 3(aq)  Ag (s) + Cu(NO 3 ) 2(aq) Cu (s) + 2AgNO 3(aq)  Ag (s) + Cu(NO 3 ) 2(aq) 3) Repeat step 2 for the rest of the elements Now we have 2 Ag, so balance the other side Now we have 2 Ag, so balance the other side Cu (s) + 2AgNO 3(aq)  2Ag (s) + Cu(NO 3 ) 2(aq) Cu (s) + 2AgNO 3(aq)  2Ag (s) + Cu(NO 3 ) 2(aq) 4) Count elements on each side of the final equation to ensure they balance: 1 Cu (s) = 1 Cu (s) ; 2Ag = 2Ag (s) ; 2 NO 3 = (NO 3 ) 2(aq) 1 Cu (s) = 1 Cu (s) ; 2Ag = 2Ag (s) ; 2 NO 3 = (NO 3 ) 2(aq) Balancing Chemical Equations

What do you remember? Composition (Formation) Composition (Formation) Decomposition Decomposition Combustion Combustion Single Replacement Single Replacement Double Replacement Double Replacement CH 4(g) + O 2(g)  CO 2(g) + H 2 O (g) CH 4(g) + O 2(g)  CO 2(g) + H 2 O (g) Mg (s) + O 2(g)  MgO (s) Mg (s) + O 2(g)  MgO (s) Cu (s) + AgNO 3(aq)  Ag (s) + Cu(NO 3 ) 2(g) Cu (s) + AgNO 3(aq)  Ag (s) + Cu(NO 3 ) 2(g) CaCl 2(aq) + Na 2 CO 3(aq)  CaCO 3(s) + NaCl (aq) CaCl 2(aq) + Na 2 CO 3(aq)  CaCO 3(s) + NaCl (aq) H 2 O (l)  O 2(g) + H 2(g) H 2 O (l)  O 2(g) + H 2(g) In Science 10 you learned about five reaction types, can you match them up

Classifying Chemical Reactions: Composition (Formation) 2Mg (s) + O 2(g)  2MgO (s) element + element  compound Predict and balance the following: Li(s) + Cl2(g)  Na(s) + F2(g)  Ba(s) + N2(g) 

Classifying Chemical Reactions: Decomposition 2H 2 O (l)  O 2(g) + 2H 2(g) compound  element + element Predict and balance the following: NaCl (s)  Sr 3 P 2(s)  Cs 2 O (s) 

Classifying Chemical Reactions: Combustion CH 4(g) + 2O 2(g)  CO 2(g) + 2H 2 O (g) fuel + oxygen  carbon dioxide + water Predict and balance the following: C 3 H 8(g) + O 2(g)  C 2 H 6(g) + O 2(g)  C 4 H 10(g) + O 2(g) 

Classifying Chemical Reactions: Single Replacement 2AgNO 3(aq) + Cu (s)  Cu(NO 3 ) 2(aq) + 2Ag (s) compound + element  compound + element 2NaI (aq) + Cl 2 (g)  I 2 (s) + 2NaCl (aq) Predict and balance the following: NaBr (aq) + O 2(g)  CuCl 2(aq) + Al (s)  Li 2 CO 3(aq) + K (s) 

Classifying Chemical Reactions: Double Replacement 2AgNO 3(aq) + CuCl 2(aq)  Cu(NO 3 ) 2(aq) + 2AgCl (aq) compound + compound  compound + compound CaCI 2(aq) + Na 2 CO 3 (aq)  2NaCl (aq) + CaCO 3(s) Predict and balance the following: NaBr (aq) + MgO (aq)  CuCl 2(aq) + AlF 3(aq)  Li 2 CO 3(aq) + K 2 O (aq) 

Chemical Puzzler

Using the solubility table: