1. Chemistry November 25

2. Types of Chemical Reactions
Combination Reactions – 2 or more substances react to form a single new substance.
Ex. 2Mg(s) + O2(g) → 2MgO(s)
**Combination Reactions release large amounts of energy**

3. When 2 nonmetals react, more than one combination is often possible.
Ex. S(s) + O2(g) → SO2(g) sulfur dioxide OR 2S(s) + 3O2(g) → 2SO3(g) sulfur trioxide

4. Also, when a transition metal and nonmetal react, more than one product is often possible.
Fe(s) + S(s) → FeS(s) iron (II) sulfide OR 2Fe(s) + 3S(s) → Fe2S3(s) iron (III) sulfide **Look at Table 9.2 on p. 255 for the common transition metal ions.

5. How to predict whether product is solid, liquid, or gas
solid + liquid = solution(aqueous) unless they said a solid compound was formed  if they use the key word solution it is aqueous  all metals are solid except mercury  non metals are gas or liquid
There are solubility charts

6. Practice
Finish and balance the following equations. How many possible reactions are there for each? What is the name of the product compound(s)?
Ca (s) + O2(g) →
Mn(s) + Cl(g) →
P(s) + Cl(g) →

7. Decomposition Reaction
A single compound breaks into 2 or more simpler products. Decomposition reactions require energy (usually heat).
Complete practice problems 15 and 16 on p.332.

8. Complete and balance the decomposition reaction HI →

9. HI → H+ + I-
Remember, H and I are diatomic molecules
HI → H2 + I2
Now you must balance the equation.
2HI → H2 + I2

10. Write the formula for the binary compound that decomposes to the products H2 and Br2.

11. Since H is 1+ and Br is 1+, the compound that forms H2 and Br2 is HBr

12. Single-Replacement Reactions
One element replaces a second element in a compound. Which metal replaces another depends on the reactivity series. Table 11.2 p. 333.

13. Example: Zn(s) + H2SO4(aq) →
Remember: Zn2+ SO42- So.. Zn(s) + H2SO4(aq) → ZnSo4(aq) + H2(g) Is balanced.

14. Balance Cl2(aq) + NaBr(aq) → NaCl(aq) + Br2(aq)

15. Do Practice Problem 17 on p. 334 in groups. Answers are on next slides

16. Fe(s) + Pb(NO3)2(aq) → Fe(NO3)(aq) + Pb(s) Make the equation possible:
Complete the equation, balance each equation, and write “no reaction” if a reaction does not occur.
Fe(s) + Pb(NO3)2(aq) →
Fe is more reactive than Pb so the reaction will proceed.
Write the equation:
Fe(s) + Pb(NO3)2(aq) → Fe(NO3)(aq) + Pb(s)
Make the equation possible:
Fe(s) + Pb(NO3)2(aq) → Fe(NO3)2(aq) + Pb(s)
Balance the equation

17. b. Cl2(s) + NaI(aq) → Complete: Cl2(s) + NaI(aq) → NaCl(aq) + I(s) Make the equation possible: Cl2(s) + NaI(aq) → NaCl(aq) + I2(s) Balance: Cl2(s) + 2NaI(aq) → 2NaCl(aq) + I2(s)

18. c. Ca(s) + H20(l) → Complete: Ca(s) + H20(l) → Ca(OH)(aq) + H(g) Make the equation possible: Ca(s) + H2O(l) → Ca(OH)2(aq) + H2(g) Balance: Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)

19. Double Replacement Reactions
Exchange of positive ions between 2 compounds.
Only happens if:
One of the products is a precipitate
One of the products is a gas
One of the products is a molecular compound such as water.

20. Ex Write a balanced equation for CaBr2(aq) + AgNO3(aq) →
Write the equation: CaBr2(aq) + AgNO3(aq) → CaNO3(aq) + AgBr(s) Make the equation possible: CaBr2(aq) + AgNO3(aq) → Ca(NO3)2(aq) + AgBr(s) Balance the equation: CaBr2(aq) + 2AgNO3(aq) → Ca(NO3)2(aq) + 2AgBr(s)

21. Write a balanced equation for FeS(s) + HCl(aq) →
Write the equation FeS(s) + HCl(aq) → FeCl(aq) + HS(g) Make the equation possible FeS(s) + HCl(aq) → FeCl2(aq) + H2S(g) Balance the equation FeS(s) + 2HCl(aq) → FeCl2(aq) + H2S(g)

22. Practice Problems p. 335
Answers on next slides

23. 18. Write the product and balance the equation of the following reaction:
a.NaOH(aq) + Fe(NO3)3(aq) →
(iron (III) hydroxide is precipitate)
Write the equation:
NaOH(aq) + Fe(NO3)3(aq) → Na(NO3)(aq) + Fe(OH)(s)
Make the equation possible:
NaOH(aq) + Fe(NO3)3(aq) → Na(NO3)(aq) + Fe(OH)3(s)
Balance the equation:
3NaOH(aq) + Fe(NO3)3→ 3Na(NO3)(aq) + Fe(OH)3(s)

24. b. Ba(NO3)2(aq) + H3PO4(aq) → (barium phosphate is a precipitate)
Write the equation:
Ba(NO3)2(aq) + H3PO4(aq) → Ba(PO4)(s) + HNO3(g)
Make the equation possible:
Ba(NO3)2(aq) + H3PO4(aq) → Ba3(PO4)(s) + HNO3(g)
Balance the equation:
3Ba(NO3)2(aq) + 2H3PO4(aq) → Ba3(PO4)2(s) + 6HNO3(aq)

25. 19. Write a balanced equation for each reaction.
KOH(aq) + H3PO4(aq) →
Write the equation:
KOH(aq) + H3PO4(aq) → KPO4(s) + H20(l)
Make the equation possible:
KOH(aq) + H3PO4(aq) →K3PO4(s) + H2O(l)
Balance the equation:
3KOH(aq) + H3PO4(aq) →K3PO4(s) + 3H2O(l)

26. 19b. H2SO4(aq) + Al(OH)3(aq) →
Write the equation: H2SO4(aq) + Al(OH)3(aq) → AlSO4(g) + H2O(l) Make the equation possible: H2SO4(aq) + Al(OH)3(aq) → Al2(SO4)3(g) + H2O(l) Balance the equation: 3H2SO4(aq) + 2Al(OH)3(aq) → Al2(SO4)3(g) + 6H2O(l)

27. Combustion Reactions
Chemical change in which an element or a compound reacts with oxygen. Energy is produced.
Ex: 2Mg(s) + O2(g) → 2MgO(s)
**combustion reactions also fall into another category of reaction. The above example is also a combination reaction.

28. Example p. 337 Write the reaction, then balance the equation.
Complete combustion of C6H6(l)
Write the equation:
C6H6(l) + O2(g) → CO2(g) + H2O(l)
Balance the equation:
2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(l)

29. Ex. p. 337
b. Complete combustion of CH3CH2OH(l) Write the equation: CH3CH2OH(l) + O2(g) → CO2(g) + H2O(l) Balance the equation: CH3CH2OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l)

30. Do Practice Problems p , 21
Answers on next slide

31. 337 #20 Write a balance equation for the combustion of
HCOOH
Write the equation:
HCOOH + O2(g) → CO2(g) + H2O(l)
Balance the equation:
2HCOOH + 2O2(g) → 2CO2(g) + 2H2O(l)

32. b. Write a balanced equation for the combustion of C7H16
b. Write a balanced equation for the combustion of C7H16. Write the equation: C7H16(l) + O2(g) → CO2(g) + H2O(l) Balance the equation: C7H16(l) + 11O2(g) → 7CO2(g) + 8H2O(l)

33. p. 337 #21 Write a balanced equation for the combustion of C6H12O6 Write the equation: C6H12O6(s) + O2(g) → CO2(g) + H2O(l) C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l)

34. Homework:
P. 339 # 22-27
Worksheet