Reviewing Reactions

Chem I | Chem II AP
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Determine the charge of the underlined atom:
1)
HBrO4
H is always +1 and O is always -2 so you have to figure out the charge for Br so that the molecule will be neutral.
+1 + ____ + 4 (-2) = 0
+1 + _+7_ + -8 = 0
2)
P2O5
O is always -2 so you have to figure out the charge for P so that the molecule will be neutral.
2(___) + 5 (-2) = 0
2(_+5_) + -10 = 0
3)
Mg(ClO3)2
Mg is always +2 and O is always -2 so you have to figure out the charge for Cl so that the molecule will be neutral.
+2 + 2 (____ + 3 (-2)) = 0
2 (____ + -6) = -2
____ + -6 = -1
_+5_ + -6 = -1
4)
K2CO3
K is always +1 and O is always -2 so you have to figure out the charge for C so that the molecule will be neutral.
+1 + ____ + 3 (-2) = 0
+1 + _+5_ + -6 = 0
5)
SO3-2
O is always -2 so you have to figure out the charge for S so that the molecule will have a total -2 charge.
____ + 3 (-2) = -2
_+4_ + -6 = -2
6)
CuCl
Although both of these atoms can have a varying charge, the halogen, Cl is more likely to follow the periodic trend than the metal is.
____ + -1 = 0
_+1_ + -1 = 0
7)
Fe(ClO3)3
The chlorate ion, ClO3, is always -1 so you have to figure out the charge for Fe so that the molecule will be neutral.
____ + 3(-1) = 0
_+3_ + -3 = 0
8)
MnO4-
O is always -2 so you have to figure out the charge for Mn so that the molecule will have a total -1 charge.
____ + 4 (-2) = -1
_+7_ + -8 = -1
Name these compounds:
9)
Mg(ClO3)2
10)
H3PO4
11)
NaHCO3
12)
HClO
13)
FeSO4
14)
H2SO3
15)
HBrO4
16)
H3PO2
17)
HBr
18)
HNO2
19)
KIO4
20)
NaClO2
21)
SO3
22)
P2O5
23)
NO2
24)
CO
Complete and balance these reactions, if no reaction write NR:
25)
Na
+
Br2
26)
NaBr
+
Pb(NO3)2
+

The insoluble product is PbBr2 because bromides are typically soluble but Ca is an exception.

27)
K2CO3
+
HCl
+
+

The double displacement product is H2CO3, but that doesn't exist. It immediately breaks down into CO2 and water.

28)
Ag
+
HCl

Silver cannot replace hydrogen from water, steam or acids, so this reaction will not occur.

29)
C6H6
+
O2
+
30)
Na2SO4
+
Zn

Na is higher than Zn on the activity series so this reaction will not occur.

31)
(NH4)2S
+
Mg(NO3)2
+

MgS is the insoluble product because sulfids are typically insoluble and Mg is not an exception.

32)
A solution of sodium hydroxide is added to a solution of potassium chloride.
+

All products are soluble. No reaction occurs. There is no precipitate.

33)
Calcium reacts with hydrochloric acid.
+
+

Calcium can displace hydrogen from water, steam and acids.

34)
Fluorine gas is bubbled through a solution of sodium iodide.
+
+

Fluorine is higher on the activity series for nonmetals than iodine, so the reaction will occur. The flourine gas is reduced. Its oxidation number changes from 0 to -1.

35)
Butyne (C4H6) is burned in air.
+
+

The product for all combustion reactions is CO2 and water.

36)
A strip of magnesium metal is added to a solution of silver nitrate.
+
+

Magnesium is higher than silver on the activity series, therefore this reaction will occur. The magnesium is oxidized. Its oxidation number changes from 0 to +2.

Complete and balance. Write the net ionic equation (if there is one).
37)
MgBr2(aq)
+
KOH(aq)
+
Net ionic equation:
+
Spectator ions?
and
38)
HCl(aq)
+
KOH(aq)
+
Net ionic equation:
+
Is this redox or precipitation?
39)
Zn(NO3)2(aq)
+
K2S(aq)
+
Net ionic equation:
+
Spectator ions?
and
40)
NH4Cl(aq)
+
Pb(C2H3O2)2(aq)
+
Net ionic equation:
+
Spectator ions?
and
41)
Zn(s)
+
HCl(aq)
+
Net ionic equation:
+
+
Spectator ions?
What gas is produced?
42)
Given: Al + Ni(NO3)3 → Al(NO3)3 + Ni
Oxidation half-reaction:
Reduction half-reaction:
Add the half-reactions:
Substance oxidized:
Substance reduced:
43)
Which of the following will form an insoluble salt with the ammonium ion?
chloride
sulfate
carbonate
hydroxide
None of these will form an insoluble salt with the ammonium ion because ammonium salts are always soluble (no exceptions).
44)
Hydrogen chloride gas is oxidized by oxygen gas.
Balanced equation:
+
+
If four moles of hydrogen chloride gas and four moles of oxygen gas react as completely as possible, which reactant, if any, is present in excess?
O2 is in excess - you need all four moles of HCl to react with only one mol of O2.
45)
Balance: (basic environment)
MnO4- → MnO2
Fe+2 → Fe+3
H2O
+
MnO4-
+
Fe+2
MnO2
+
Fe+3
+
OH-