ABC-R Lab #1 Test
Nickel Cycle
Name ______________________________
Reaction #1 Nickel metal reacts with the weak acid sulfurous acid.
Ni (s) + H2SO3(aq)  NiSO3 (aq) + H2(g)
1. Sulfurous acid is a weak acid.
a. Write the reversible reaction that occurs at equilibrium in an aqueous solution of sulfurous acid.
b. Write the Ka expression for the equilibrium constant. Ka = 1.7 x 10-2. What does this tell you about the
relative amounts of ions and molecules in the solution?
c. After the nickel is added, H+ ions from the weak acid equilibrium leave the solution as H2 gas, how does
this shift the equilibrium of the weak acid in 1a (not the reaction shown: Ni(s) with the acid?
 Use Le Chatelier’s principle to predict the direction of shift. Address three keys points.

Use collisions to explain the shift in equilibrium. Include which reaction is affected by the change in
concentration, whether that reaction will be faster or slower and why, which reaction will be faster
and the direction of the shift.
d. Referring the reaction #1 shown at the top, why are hydrogen ions leaving solution?
2. Write the total ionic and the net ionic equations for Reaction #1. Ni (s) + H2SO3(aq)  NiSO3 (aq) + H2(g)
Ni (s) + H2SO3(aq)
 NiSO3 (aq) +
H2(g)
3. Assign oxidation numbers to each element in the molecular equation.
Identify the species oxidized by connecting them above.
Identify the species reduced by connecting them above.
4. Write a half-reaction to show the oxidation. Did it gain or lose electrons?
5. Write a half-reaction to show the reduction of hydrogen ions. Did it gain or lose electrons?
Ni (s) + H2SO3(aq)  NiSO3 (aq) +
H2(g)
6. Describe what happened in the reaction. Include collisions and electrons transferred. Use the half reactions
to help describe what happened.
7. Identify the reaction type. Two answers.
6. Draw the complete electron configuration for nickel.
Assign quantum numbers to one of the valence electrons in each of the last two orbitals (two different
subshells). Explain what the first and second quantum number indicate.
Use quantum numbers to explain why the 4s orbital fills before the 3d orbital.
7. Compare and contrast the nickel in the reactant and the product of Reaction #1
BEFORE – atom, ion or molecule
AFTER– atom, ion or molecule
Name and describe the bonding or attractions before and after.
BEFORE
AFTER
9. If 4.0 M H2SO3 is used, calculate the volume in mL required to completely react with 0.435 grams of nickel.
10. If excess sulfurous acid is added, what will be limiting reactant?
Calculate how many grams of nickel (II) sulfite will be produced.
11. Would filtering the solution allow you to recover the aqueous nickel (II) sulfite? Remember excess
sulfurous acid was added. Explain your reasoning.
ABC-R Lab 1 Test Page two
Name ________________________________ period ___
Reaction #2 nickel (II) sulfite in solution reacts with hydrochloric acid.
NiSO3(aq) + HCl(aq)  NiCl2(aq) + SO2(g)
+ H2O(l)
1. a. Balance the equation.
b. Write the total ionic and the net ionic equations.
c. Describe what happened in the reaction.
2. Identify the reaction type.
3. Draw the Lewis structure for the sulfite ion.
a. Determine the electron pair geometry.
b. Determine the molecular geometry.
c. Determine the orbital hybridization.
4. Draw the Lewis structure for the sulfur dioxide.
a. Determine the electron pair geometry.
b. Determine the molecular geometry.
c. Determine the orbital hybridization.
5. Determine the polarity of the S-O bond using electronegativity. Describe the bond between the atoms.
Name and describe the attraction between SO2 molecules based upon the bond between the atoms.
Reaction #3 nickel (II) chloride reacts sodium hydroxide
NiCl2(aq) + NaOH (aq)  Ni(OH)2(s)
+ NaCl(aq)
1. Balance the equation and identify the reaction type.
How will the appearance of the solution change as a result?
2. Write the total and net ionic equations for the reaction.
Describe what happened in the reaction. Use the net ionic equation to help you describe what happened.
3. The reversible reaction that occurs in the saturated solution of nickel hydroxide.
Ni(OH)2(s)
 Ni2+ (aq) + 2 OH- (aq)
a. Write the Ksp expression. The Ksp of nickel hydroxide is 5.5 x 10-16
b. Use the Ksp to explain why some nickel ions remain in solution at equilibrium.
c. Describe the equilibrium in a saturated solution. Include a description of both reactions and address the
ions in the solid and solution.
d. Use the Ksp to calculate the concentration of nickel hydroxide in the saturated solution.
c. Explain how adding excess sodium hydroxide will insure that “all” of the nickel ions are present in the
precipitate rather than in solution. Use Le Chatelier’s Principle to justify.
4. At the start of these procedures the mass of nickel was 0.435 grams. If 0.628 grams of nickel hydroxide is
recovered, calculate the percent yield. Hint: You need to calculate nickel hydroxide expected first.
ABC-R Lab 1 Test Page three
Name ________________________________ period ___
Reaction #4
Sulfuric acid a strong acid is poured through the filter paper containing the nickel hydroxide solid.
Ni(OH)2(s)
+ H2SO4(aq)
 NiSO4(aq)
+
H2O(l)
1. Identify the type of reaction.
2. The reversible reaction occurring at equilibrium
a. The hydrogen ions from the acid react with the hydroxide ions in the saturated solution of nickel
hydroxide from the previous reaction.. What happens to the concentration of hydroxide ions?
b. Based upon the change in the concentration of hydroxide ions, use Le Chatelier’s Principle to predict the
shift in equilibrium for the saturated solution of nickel hydroxide Explain your reasoning.
Ni(OH)2(s)
 Ni2+ (aq) + 2 OH- (aq)
c. Use collisions to describe the shift in equilibrium. Include which reaction is affected by the change in
concentration, whether that reaction will be faster or slower and why, which reaction will be
faster and the direction of the shift.
2. Sulfuric acid is a strong acid. How does this compare to the weak acid sulfurous acid? When you write a
total ionic equation involving these two acids, how would each appear in the equation?
Reaction #5 Solid aluminum is added to the nickel sulfate solution.
Al(s) +
Ni SO 4 (aq) 
Al 2 (SO 4 ) 3 (aq) +
Ni(s)
1. Assign oxidation numbers to each element.
2. Balance the equation.
3. Identify the reaction type.
4. Write the oxidation half-reaction.
4. Write the reduction half-reaction.
6. What is the minimum mass of aluminum required to completely recover all of the 0.391 g of Ni that was
originally used?
8. Describe the steps to isolate and measure the mass of nickel. Include an explanation of how each procedure
will further isolate the nickel. You have three lab procedures that isolate the nickel as well as a description
of the mass measurements required.
ABC-R Lab #1 Test
Nickel Cycle
Name ______________________________
Reaction #1 Nickel metal reacts with the weak acid sulfurous acid.
Ni (s)
+
H2SO3(aq)  NiSO3 (aq) + H2(g)
weak acid
1. Sulfurous acid is a weak acid.
a. Write the reversible reaction that occurs at equilibrium in an aqueous solution of sulfurous acid.
H2SO3(aq)  2 H+ (aq) + SO32-(aq)
b. Write the Ka expression for the equilibrium constant. Ka = 1.7 x 10-2. What does this tell you about the
relative amounts of ions and molecules in the solution?
Weak acid and equilibrium
Writing reversible
reactions
Shifts with Le Chatelier’s
and collisions
H2SO3(aq)  2 H+ (aq) + SO32-(aq)
Ka = [H+] [SO32-]
[H2SO3]
Since the Ka is less than one, the denominator (concentration molecules of H2SO3) of
the fraction, must be larger than the numerator (ions of [H+] [SO32-])
c. After the nickel is added, H+ ions from the weak acid equilibrium leave the solution as H2 gas, how does
this shift the equilibrium of the weak acid in 1a (not the reaction shown: Ni(s) with the acid?
 Use Le Chatelier’s principle to predict the direction of shift. Address three keys points.
H2SO3(aq)  2 H+ (aq) + SO32-(aq)
Decrease [H+] – product is removed
System responds to replace product
Shift to the right _ products are on the right side

Use collisions to explain the shift in equilibrium. Include which reaction is affected by the change in
concentration, whether that reaction will be faster or slower and why, which reaction will be faster
and the direction of the shift.
H2SO3(aq)  2 H+ (aq) + SO32-(aq)
Decrease [H+] affects the reverse reaction of H+ colliding with SO32- ions
With less H+ ions in solution less likely to collide with SO32- ions – decrease rate of reverse reaction
Therefore the forward reaction will be faster than the reverse reaction (not faster than it was before just
faster than the reverse that slowed down)
The shift is to the right since the forward reaction is faster
Until the reactions return to equilibrium – rates once again equal OR run out of H2SO3
d. Referring the reaction #1 shown at the top, why are hydrogen ions leaving solution?
H+ ions leave the solution as hydrogen gas.
2. Write the total ionic and the net ionic equations for Reaction #1. Ni (s) + H2SO3(aq)  NiSO3 (aq) + H2(g)
Ni (s)
+
H2SO3(aq)

2+
NiSO3 (aq)
Ni (s) + H2SO3(aq)  Ni (aq)
Do not split up the
since it is a weak acid
0
+1 +4 -2
Ni (s) + H2SO3(aq)
+
2-
+
H2(g)
SO3 (aq) + H2(g)
split up the NiSO3 (aq)
Writing net ionic equations to
since it an ionic compound show ions dissociated in solution
in solution the ions dissociate
+2 +4 -2
 NiSO3 (aq) +
0
H2(g)
Assigning oxidation numbers
3. Assign oxidation numbers to each element in the molecular equation.
Identify the species oxidized by connecting them above.
Identify the species reduced by connecting them above.
4. Write a half-reaction to show the oxidation. Did it gain or lose electrons?
Ni (s)  Ni2+ (aq) + 2e28 p
28 e-
Oxidation and Reduction
Writing half reactions
28p
26e-
5. Write a half-reaction to show the reduction of hydrogen ions. Did it gain or lose electrons?
2 H+ (aq) + 2 e-  H2(g)
1p
1p 1p - two H atoms
0 e1e- 1eNi (s) + H2SO3(aq)  NiSO3 (aq) +
H2(g)
6. Describe what happened in the reaction. Include collisions and electrons transferred.
Using half reaction to describe reactions at particle
levels with collisions and electron transfers
Use the half reactions to describe what happened.
H+ ions (from the sulfurous acid equilibrium) collide with solid nickel. If they collide with enough KE and
right orientation, they steal an electron and become hydrogen atoms. Two H atoms will then get together and
form nonpolar covalent bonds and leave the solution as H2 gas. Nickel atoms became nickel ions and moved
into solution forming ion-dipole attractions with water molecules. This leads to a shift in the weak acid
equilibrium to replace the lost ions and thus the reaction continues until either you run out of H+ or Ni.
7. Identify the reaction type. Two answers. Single replacement reaction and redox
6. Draw the complete electron configuration for nickel.
1s
2s
2p
3s
3p
Drawing e- configuration including Hund’s rule
4s
3d
Assign quantum numbers to one of the valence electrons in each of the last two orbitals (two different
subshells). Explain what the first and second quantum number indicate.
Oxidation numbers and linking the
number to the orbitals and e- distribution
e- in 4s orbital
400½
or 4 0 0 -½
e- in 3d orbital
320½
or 3 2 0 -½ third number could also be -2, -1, 1, or 2
first quantum number tells the energy level – related to distance from the nucleus
second quantum number tells shape of orbital – is is s, p, d, or f shaped orbital
third quantum number tells orientation in space – which one of the orbitals?
fourth number tells spin up or down
Use quantum numbers to explain why the 4s orbital fills before the 3d orbital.
Sum of the first two quantum numbers reflects the relative energy – lower sum represents lower PE thus
electrons fill orbital before filling one of higher energy
Oxidation numbers and filling orbitals
4s = 4+0 = 4 3d = 3+2 = 5 so 4s lower sum fills first
Identifying and describing particles
and the bonding between them
7. Compare and contrast the nickel in the reactant and the product of Reaction #1
Ni (s) BEFORE – atom, ion or molecule
Ni2+ (aq) AFTER– atom, ion or molecule
Atom
Ion in solution
Name and describe the bonding or attractions before and after.
BEFORE
Metallic bonds hold atoms in fixed positions
Electrons move freely in a sea of electrons shared by
all the atoms
AFTER
Positive Ni2+ ion is attracted to the negative –end of
water molecule – ion-dipole attraction
9. If 4.0 M H2SO3 is used, calculate the volume in mL required to completely react with 0.435 grams of nickel.
0.435 g Ni
1 mol Ni
58.71 g Ni
1 mol H2SO3
1 mol Ni
1 L sol’n
4 mol H2SO3
1000 mL sol’n
1 L sol’n
1.85 mL
Calculating using moles and reaction
10. If excess sulfurous acid is added, how many grams of nickel (II) sulfite will be produced?
0.435 grams of nickel
Calculating using moles and reaction
0.435 g Ni
1 mol Ni
58.71 g Ni
1 mol NiSO3
1 mol Ni
138.771 g
1 mol NiSO3
1.03 g
11. Would filtering the solution allow you to recover the aqueous nickel (II) sulfite? Explain your reasoning.
The nickel sulfite AND the left-over sulfurous acid will both go through the filter since they are ions in solution
and each is small enough to get through the pores of the filter. Thus filtering will not isolate the nickel sulfite.
Separation lab techniques
ABC-R Lab 1 Test Page two
Name ________________________________ period ___
Reaction #2 nickel (II) sulfite in solution reacts with hydrochloric acid.
NiSO3(aq) + 2 HCl(aq)  NiCl2(aq) + SO2(g)
+ H2O(l)
1. a. Balance the equation.
b. Write the total ionic and the net ionic equations.
Balancing equation
Writing ionic equations
Remember. What happens to ions in solution? In a solid?

NiCl2(aq)
+ SO2(g)
2+
+ Cl (aq)  Ni (aq) + Cl (aq) + SO2(g)
+ H2O(l)
+ H2O(l)
Ni2+(aq) + SO32-(aq) + H+(aq) + Cl-(aq)  Ni2+(aq) + Cl -(aq) + SO2(g)
+ H2O(l)
Ni
2+
NiSO3(aq)
SO32-(aq)
+
+
2 HCl(aq)
-
(aq) +
+ H (aq)
split up the NiSO3 (aq)
split up the HCl
Again – split up these ions
leave both these molecules
since it an ionic compound since it is a strong acid
be sure to show the charges
together
in solution the ions dissociate the ions completely ionize
SO32-(aq) + H+(aq) +  SO2(g)
+ H2O(l)
c. Describe what happened in the reaction. Use the net ionic equation to help you describe what happened.
Use the net ionic equation to help you describe what happened.
2-
+
SO3 (aq) + H (aq) +  SO2(g)
+ H2O(l)
Using ionic equations and
collisions to describe reactions
Notice the SO32- ion loses an O and neg 2 charge – so must have lost an O2- ion
That O2- ion must have got together with an H+ to make OHthen another H+ to make H2O molecules
2. Identify the reaction type. Double replacement that produces a gas
3. Draw the Lewis structure for the sulfite ion.
a. Determine the electron pair geometry.
b. Determine the molecular geometry.
c. Determine the orbital hybridization.
4. Draw the Lewis structure for the sulfur dioxide.
a. Determine the electron pair geometry.
b. Determine the molecular geometry.
c. Determine the orbital hybridization.
Lewis structures
VSEPR – EP geometry,
molecular geometry and
orbital hybridization
Using EN to identify bond
Describing the behavior of e- in the bond (polar covalent the
unequal sharing, etc)
Identifying and describing attractions between molecules
(the attraction between oppositely charged ends
5. Determine the polarity of the S-O bond using electronegativity. Describe the bond between the atoms.
Describe the sharing. What happens to the electrons?
Sulfur - electronegativity
2.5 A difference in EN of 1.0 indicates polar covalent bond
Oxygen - electronegativity
3.5
Difference in electronegativity
1.0 0 – 0.5 nonpolar 0.5 – 1.9 polar g
The oxygen pulls harder on the shared pair of electrons thus the shared pair of electrons spends more time at the
oxygen end – leading to a partially negative pole at the oxygen end and partially positive pole at sulfur end.
Since this molecule is bent without any symmetry for the polarity the molecule is a dipole.
Describe the attraction between sulfur dioxide molecules based upon the bond between the atoms.
Since the molecule has two oppositely-charged ends – the attractions between the sulfur dioxide molecules is
dipole-dipole attraction. The negative end of one molecule is attracted to positive end of another molecule
Reaction #3 nickel (II) chloride reacts sodium hydroxide
NiCl2(aq) + NaOH (aq)  Ni(OH)2(s)
+ NaCl(aq)
1. Identify the reaction type. Double replacement – producing a precipitate
2. Write the total and net ionic equations for the reaction.
NiCl2(aq)
+
NaOH (aq)
 Ni(OH)2(s)
Ni2+(aq) + Cl -(aq) + Na+(aq) + OH-(aq)  Ni(OH)2(s)
Ionic compounds dissolve in water
The ions split up – the ions are attracted to water
Be sure to show charges on separate ions
+ NaCl(aq)
+
-
+ Na (aq) + Cl (aq)
Ionic solid
The ions are in fixed positions
The ions are attracted to each other
The sodium and chloride ions were spectator ions – they were split up and attracted to water molecules before
and after the reaction – they did not change
2+
-
Ni (aq) + 2 OH (aq)  Ni(OH)2(s)
Balancing equation
Writing ionic equations
Using ionic equations and
collisions to describe reactions
Describe what happened in the reaction.
Ni2+(aq) + 2 OH-(aq)  Ni(OH)2(s)
Nickel ions that were in solution attracted to water molecules collided with hydroxide ions that
were in solution and formed strong ionic bonds so that the ions clump together to form a solid
precipitate that makes the solution cloudy and eventually settles to the bottom.
3. Write the equation for the reversible reaction that occurs in the saturated solution of nickel hydroxide.
Hint: Only nickel hydroxide
in the solution.
2+
-
Ni (aq) + 2 OH (aq)
Ni(OH)2(s)

Saturated ionic solution and equilibrium
Writing equilibrium constants for
reversible reactions
Describing equilibrium – rates and
conditions
Calculation using Keq
a. Write the Ksp expression. The Ksp of nickel hydroxide is 5.5 x
10-16
2+
- 2
Ksp = [Ni ][ OH ]
b. Use the Ksp to explain why some nickel ions remain in solution
at equilibrium.
Since the Ksp, the product of concentration of ions in solution, is greater than zero – there must
be ions in solution albeit not many given the extremely small value of the Ksp.
c. Describe the equilibrium in a saturated solution. Include a description of both reactions and address the
ions in the solid and solution.
At equilibrium the rate of the forward reaction (ions dissociating into solution) is equal to
the rate of the reverse reaction (ions crystallizing – leaving solution), so that conditions remain
constant (for example the amount of product compared to reactant) (concentration of nickel and
hydroxide ions remain constant as long as the system remains at equilibrium).
d. Use the Ksp to calculate the concentration of nickel hydroxide in the saturated solution.
2+
-
X = [Ni(OH)2] in solution at equilibrium. So [Ni ] = X and [ OH ] = 2X
Ksp = 5.5 x 10-16 = [Ni2+] [ OH-]2
(X) (2X)2
4x3 = 5.16 x 10-6
c. Explain how adding excess sodium hydroxide will insure that “all” of the nickel ions are present in the
precipitate rather than in solution. Use Le Chatelier’s Principle to justify.
4. At the start of these procedures the mass of nickel was 0.435 grams. If 0.628 grams of nickel hydroxide is
recovered, calculate the percent yield. Hint: You need to calculate nickel hydroxide expected first.
ABC-R Lab 1 Test Page three
Name ________________________________ period ___
Reaction #4
Sulfuric acid a strong acid is poured through the filter paper containing the nickel hydroxide solid.
Ni(OH)2(s)
+ H2SO4(aq)
 NiSO4(aq)
+
H2O(l)
1. Identify the type of reaction.
Double replacement – acid/base neutralization producing water molecules.
Saturated ionic solution and equilibrium
2. The reversible reaction occurring at equilibrium
Shifts with Le Chatelier’s
a. The hydrogen ions from the acid react with the hydroxide ions in
Shifts with collisions
the saturated solution of nickel hydroxide from the previous
reaction.. What happens to the concentration of hydroxide ions?
Decrease concentration of hydroxide ions
b. Based upon the change in the concentration of hydroxide ions, use Le Chatelier’s Principle to predict the
shift in equilibrium for the saturated solution of nickel hydroxide Explain your reasoning.
Ni(OH)2(s)
 Ni2+ (aq) + 2 OH- (aq)
Remove hydroxide – a product
System responds to replace product
Product on the right so shift to the RIGHT
c. Use collisions to describe the shift in equilibrium. Include which reaction is affected by the change in
concentration, whether that reaction will be faster or slower and why, which reaction will be
faster and the direction of the shift.
Decrease concentration of hydroxide ions affects the reverse reaction (OH- ions colliding with
Ni2+ ions). A decreased concentration will result in less collisions and a slower reaction. The
forward reaction will be temporarily faster than the reverse reaction. A shift to the right (in the
direction of the faster reaction – since more product will be produced than reactant during the
shift)
2. Sulfuric acid is a strong acid. How does this compare to the weak acid sulfurous acid? When you write a
total ionic equation involving these two acids, how would each appear in the equation?
Sulfuric acid is a strong acid so it completely dissociates in solution into hydrogen ions and sulfate ions. The
bond between the hydrogen and oxygen is weaker. These ions will be shown as separate ions in the ionic
2equation. H+ (aq) + SO4 (aq)
Sulfurous acid is a weak acid, so it only partially ionizes in water. The solution contains mostly sulfurous acid
molecules with few ions of hydrogen and sulfite. The system reaches equilibrium characterized the Ka of less
than one. The will be shown as molecules (not split up) in the ionic equation. H2SO3(aq)
The more oxygen on the central atom of the polyatomic ion – the weaker the H-O bond is in oxy-acid and
consequently the stronger the acid.
Strong vs weak acid
Reaction #5 Solid aluminum is added to the nickel sulfate solution.
0
+2 +6 -2
2 Al(s) +
3 Ni S O 4 (aq) 
+3
+6 -2
0
Al 2 (SO 4 ) 3 (aq) +
3 Ni(s)
1. Assign oxidation numbers to each element.
Balancing equations
Assigning oxidation numbers
Write half reactions
Calc using moles and rxn
2. Balance the equation.
3. Identify the reaction type. Single replacement and redox
4. Write the oxidation half-reaction. Al is oxidized since its oxidation number increased
Al(s)  Al3+(aq) + 3e4. Write the reduction half-reaction. Ni is reduced since its oxidation number decreased
Ni2+(aq) + 2e-  Ni (s)
6. What is the minimum mass of aluminum required to completely recover all of the 0.391 g of Ni that was
originally used?
8. Describe the steps to isolate and measure the mass of nickel. Include an explanation of how each procedure
will further isolate the nickel.
Lab techniques to isolate and measure mass
Nickel ions in solution will be colored while aluminum ions will not – so add aluminum until the color
disappears
Remove any remaining pieces of aluminum with forceps – you cannot add an acid – it will react with
both the Al and Ni
Decant the solution leaving behind the solid nickel – rinse to remove solution clinging to solid nickel
For added good measure – the solution can be filtered and rinsed multiple times – the filter allows the
solution to pass through as well as the rinse water, but the solid nickel remains.
Allow the filter paper to dry in the oven to remove the water
Measure the mass of the filter paper before and then with the nickel – subtract to find the mass of the
nickel recovered