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1
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2
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- have two parts
- Reactants - the substances you start with
- Products- the substances you end up with
- The reactants turn into the products.
- Reactants ® Products
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3
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- The way atoms are joined is changed
- Atoms aren’t created or destroyed.
- Can be described several ways
- In a sentence
- Copper reacts with chlorine to form copper (II) chloride.
- In a word equation
- Copper + chlorine ® copper (II) chloride
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4
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- Table 11.1
- the arrow separates the reactants from the products
- Read “reacts to form”
- The plus sign = “and”
- (s) after the formula -solid
- (g) after the formula -gas
- (l) after the formula -liquid
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5
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- (aq) after the formula -
dissolved in water, an aqueous
solution.
- used after a product indicates a gas (same as (g))
- ¯ used after a product indicates a solid (same as (s))
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6
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- indicates a
reversible reaction (More later)
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shows that heat is supplied to the reaction
- is used to
indicate a catalyst used in this case, platinum.
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7
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- A substance that speeds up a reaction without being changed by the
reaction.
- Enzymes are biological or protein catalysts.
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8
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- Uses formulas and symbols to describe
a reaction
- doesn’t indicate how many.
- All chemical equations are sentences that describe reactions.
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9
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- Solid iron (III) sulfide reacts with gaseous hydrogen chloride to form
solid iron (II) chloride and
hydrogen sulfide gas.
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10
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- Nitric acid dissolved in water reacts with solid sodium carbonate to
form liquid water and carbon dioxide gas and sodium nitrate dissolved in
water.
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11
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12
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- Cu(s) + AgNO3(aq) ® Ag(s) + Cu(NO3)2(aq)
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13
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14
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- Atoms can’t be created or destroyed
- All the atoms we start with we must end up with
- A balanced equation has the same number of atoms of each element on both
sides of the equation.
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15
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- C + O2 ® CO2
- This equation is already balanced
- What if it isn’t already?
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16
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- C + O2 ® CO
- We need one more oxygen in the products.
- Can’t change the formula, because it describes what actually happens
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17
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- Must have started with two C
- 2 C + O2 ® 2 CO
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18
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- Write the correct formulas for all the reactants and products
- Count the number of atoms of each type appearing on both sides
- Balance the elements one at a time by adding coefficients (the numbers
in front)
- Check to make sure it is balanced.
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19
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- Change a subscript to balance an equation.
- If you change the formula you are describing a different reaction.
- H2O is a different compound than H2O2
- Never put a coefficient in the middle of a formula
- 2 NaCl is okay, Na2Cl is not.
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20
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21
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22
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23
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- AgNO3 + Cu ® Cu(NO3)2
+ Ag
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24
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25
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26
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27
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- If an atom appears more than once on a side, balance it last.
- If you fix everything except one element, and it is even on one side and
odd on the other, double the first number, then move on from there.
- C4H10 + O2 ® CO2 + H2O
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28
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29
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- There are too many reactions to remember
- Fall into categories.
- We will learn 5 types.
- Will be able to predict the products.
- For some we will be able to predict whether they will happen at all.
- Must recognize them by the reactants
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30
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- Combine - put together
- 2 elements, or compounds combine to make 1 compound.
- Ca +O2 ® CaO
- SO3 + H2O ® H2SO4
- We can predict the products if they are two elements.
- Mg + N2 ®
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31
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32
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- Fe + O2 ® iron (II)
oxide
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33
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- Al + O2 ®
- Remember that the first step is to write the formula
- Then balance
- Also called synthesis reaction
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34
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- If they tell you it is combination, you will make one product
- Two compounds will make a polyatomic ion.
- CO2 + H2O →
- H2O + Cl2O7→
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35
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- decompose = fall apart
- one reactant falls apart into two or more elements or compounds.
- NaCl Na + Cl2
- CaCO3 CaO
+ CO2
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36
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- Can predict the products if it is a binary compound
- Made up of only two elements
- Falls apart into its elements
- H2O
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37
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38
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- If the compound has more than two elements you must be
given one of the products
- The other product will be from the missing pieces
- NiCO3 NiO +
- H2CO3(aq)® CO2 +
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39
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- One element replaces another
- Reactants must be an element and a compound.
- Products will be a different element and a different compound.
- Na + KCl ® K + NaCl
- F2 + LiCl ® LiF + Cl2
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40
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41
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42
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- Metals replace metals (and hydrogen)
- Al + CuSO4 ®
- Zn + H2SO4 ®
- Think of water as HOH
- Metals replace one of the H, combine with hydroxide.
- Na + HOH ®
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43
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- We can tell whether a reaction will happen
- Some are more active than other
- More active replaces less active
- There is a list on page 333
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44
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- There is a list on page 333
- Higher on the list replaces lower.
- If the element by itself is higher, it happens,
- if element by itself is lower, it doesn’t
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45
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- Note the *
- H can be replaced in acids by everything higher
- Only the first 4 (Li - Na) react with water.
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46
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47
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48
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49
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50
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- What does it mean that Ag is on the bottom of the list?
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51
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- Nonmetals can replace other nonmetals
- Limited to F2 , Cl2 , Br2 , I2
- The order of activity is that on the table.
- Higher replaces lower.
- F2 + HCl ®
- Br2 + KCl ®
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52
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- Two things replace each other.
- Reactants must be two ionic compounds or acids.
- Usually in aqueous solution
- NaOH + FeCl3 ®
- The positive ions change place.
- NaOH + FeCl3 ® Fe3+OH-
+ Na+Cl-
- NaOH + FeCl3 ® Fe(OH)3
+ NaCl
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53
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54
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- Will only happen if one of the products
- doesn’t dissolve in water and forms a solid
- or is a gas that bubbles out.
- or is a covalent compound usually water.
- Polyatomic ions don’t change from side to side
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55
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- assume all of the reactions take place.
- CaCl2 + NaOH ®
- CuCl2 + K2S ®
- KOH + Fe(NO3)3 ®
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56
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- KOH + Fe(NO3)3 ®
- H3PO4
+ Ca(OH)2 ®
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57
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- Look at the reactants
- E for element
- C for compound
- E + E Combination
- C Decomposition
- E + C Single replacement
- C + C Double replacement
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58
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- Combustion
- A compound composed of only C H and maybe O is reacted with oxygen
- If the combustion is complete, the products will be CO2 and H2O.
- If the combustion is incomplete, the products will be CO and H2O.
- or just C and H2O.
- O2 will always be the second reactant
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59
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- Complete combustion of C4H10
- Incomplete combustion of C4H10
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60
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- Complete combustion of C6H12O6
- Incomplete combustion of C2H6O
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61
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- Fall apart into ions when they dissolve
- That’s why they conduct electricity when dissolved.
- So when we write them as (aq) they are really separated
- NaCl(aq) is really Na+(aq) and Cl-(aq)
- K2SO4 (aq) is really K+(aq) and
SO42-(aq)
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62
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- Many reactions happen in solution
- Makes it so the ions separate so they can interact.
- Solids, liquids, and gases are not separated, only aqueous
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63
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- Every aqueous compound is written as separate ions
- Solids, liquids and gases as whole compounds
- MgCl2(aq) + PbSO4(aq) →
MgSO4(aq) + PbCl2(s)
- Is really
- Mg2+(aq) + Cl-(aq) + Pb2+(aq) + SO4(aq)
→
Mg2+(aq) + SO4(aq) + PbCl2(s)
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64
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- FeBr3(aq) + KOH(aq) →
KBr (aq) + Fe(OH)3(s)
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65
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- CaCl2(aq) + MgSO4(aq) →
CaSO4(s) + MgCl2(aq)
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66
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- Ba(OH)2(aq) + H2SO4(aq) →
BaSO4(s) + HOH(l)
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67
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- Fe3+(aq)+ Br-(aq) + K+(aq) +OH-(aq)
→
K+(aq) +Br-(aq) + Fe(OH)3(s)
- K+ and Br- don’t change.
- They are spectator ions
- Could be eliminated
- Fe3+(aq) +OH-(aq) →Fe(OH)3(s)
- This is what really changes
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68
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- Shows only those particles that change before and after.
- Eliminate spectator ions
- Needs to be balanced in terms of both mass and charge
- Fe3+(aq) +OH-(aq) →Fe(OH)3(s)
- Fe3+(aq) +3 OH-(aq) →Fe(OH)3(s)
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69
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- HCl (aq) + Ba(OH)2 (aq) →
BaCl2(s) + HOH (l)
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70
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- Al + FeSO4(aq) → Al2(SO4)3(aq)
+ Fe
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71
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- Cl2(s) + NaI(aq) → NaCl(aq) + I2(s)
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72
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- K2CO3(aq) + MgI2(aq) →
MgCO3(s)
+ KI(aq)
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73
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- Written for single and double replacement.
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74
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- Solids formed from aqueous solution.
- You can predict them if you know some general rules for solubility.
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75
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- Salts with alkali metals and ammonium
- Salts of nitrates and chlorates
- Salts of sulfates except Ag+, Pb2+, Hg22+,
Ba2+, and Sr2+
- Salts of chlorides except Ag+, Pb2+, and Hg22+
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76
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- Carbonates, phosphates, chromates, sulfides, and hydroxides
- Unless they fall under rule # 1
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77
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- LiBr
- Ba(NO3)2
- CaSO4
- PbCl2
- CaCO3
- K2CO3
- Cd(ClO3)2
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78
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- For double replacement- has to make gas, solid or water.
- Water from an acid- H+
and a hydroxide- OH- makes HOH
- Solids- from solubility rules
- Exchange ions and see if something is insoluble
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79
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- MgSO4 + NaOH →
- H2SO4 + KOH →
- K3PO4 + FeF3→
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80
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81
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- Describes a reaction
- Must be balanced to follow the
- Law of Conservation of Mass
- Can only be balanced by changing
- Has special symbols to indicate state, and if catalyst or energy is
required.
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82
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- Come in 5 types.
- Can tell what type they are by the reactants.
- Single Replacement happens based on the activity series
- Double Replacement happens if the product is a solid, water, or a gas.
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83
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- 1. Determine the type by looking at the reactants.
- 2. Put the pieces next to each other based on type
- 3. Use charges to write the formulas
- 4. Use coefficients to balance the equation.
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Notes
