CHEM120L Study Guide - Final Guide: Weak Base, Perchlorate, Rydberg Formula

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Published on 18 Apr 2013
School
University of Waterloo
Department
Chemistry
Course
CHEM120L
Experiment 1 & 2
Experiment #1: The Chemistry of Copper Compounds
Synthesis of Copper compounds form metallic compounds
o Cu Cu(NO3)2 Cu(OH)2 CuO CuSO4 5H2O Cu
Synthesis of Copper (II) Nitrate and Copper (II) Hydroxide
o Cu(s) + 4NO3(aq) Cu(NO3)2(aq) + 2NO2(g) +2H2O(l)
o Cu(NO3)2(aq) + 2NaOH(aq) Cu(OH)2(s) + 2NaNO3(aq)
Synthesis of Copper (II) Oxide
o Cu(OH)2(aq) CuO(s) + H2O(l)
Synthesis of Copper (II) Sulphate
o CuO(s) + H2SO4(aq) CuSO4(aq) + H2O(l)
Recovery of Copper
o CuSO4(aq) + Zn(s) Cu(s) + ZnSO4(aq)
o Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)
Percent Recovery
o ( Initial Mass / Recovered Mass ) x 100%
Common Errors:
o Bumping: superheating causing overflowing of liquid due to
bubbles forming rapidly
o Weighing the final sample of recovered copper when it is still
wet, giving a higher mass and a larger percent
o The overheating of Copper or the loss of copper in the
decanting the supernatant
Experimental Procedure
o Part 1: Synthesis of Copper (II) Nitrate and Copper (II)
Hydroxide
Obtain an length of copper wire and a piece of
sandpaper, sand wire and weigh on analytical balance
Place copper wire in beaker in fume hood with 10 mL of
Nitric Acid, let wire dissolve, bright blue solution
Dilute with 25mL of deionized water, stir in 25mL of
20% NaOH
o Part 2: Synthesis of Copper (II) Oxide
Heat the mixture and stir to prevent bumping until
boiling point is reached, then heat for one more minute
or until completely black, add more NaOH(20mL) until
black
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Isolate with solid CuO with vacuum filtration, using
Buchner funnel to quantitively transfer CuO
Use three 10mL portions of deionized water to rinse out
the beaker into the funnel
Wash the CuO with water to replace the NaNO3 and
NaOH with water. Collect all CuO on filtrate paper
o Part 3: Synthesis of copper (II) Sulphate
Convert CuO to CuSO4 with dilute sulphuric acid
CuO is water soluble and dissolves releasing Cu2+ ions
that are hydrated to form Cu(H2O)42+. Due to high
solubility the copper sulphate will not be isolated to
produce Cu
Transfer CuO back into original beaker from filtrate
paper and wash the paper with 20mL of 3M H2SO4 use
10mL of deionized water to wash out the acid
If the black CuO doesn’t dissolve completely, boil gently
until it is dissolved giving a blue solution, use 5mL
water to rinse adhering solution out after transferring
supernatant liquid to a 100mL beaker
o Part 4: Recovery of Copper
Zinc is more chemically active than copper and
displaces copper (II) ions from solution, and settles
quickly. The excess zinc is removed with HCl. When H
gas bubbles stop, Zn is completely dissoluted
2g of zinc was weighed using the top loading balance
and was added in small portions to the blue Copper (II)
sulphate solution. The solution was stirred until the blue
colour disappeared (copper(II) sulphate converted to
copper and Zinc Sulphate) The solid is Zn and Cu metal
Add 10mL of 6M HCl in the fume hood to dissolve the
Zn
When the reaction of Zn and HCl has stopped the
copper was allowed to settle and the supernatant was
decanted. The solid was washed with two separate
50mL portions of water. Decant after washing
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Using the analytical balance, weigh a clean and dry
evaporating dish. Transfer the Cu to the evaporating
dish using as little water as possible to wash it out.
Warm the dish until the water is evaporated but do not
burn off the Cu. Allow to cool, and weigh again.
Experiment #2: Acid-Base Titrations: The Identification of an
Unknown Solid Acid
Strong and Weak Acids
o Strong acids are fully ionized in aqueous solution, weak acids
are only partially ionized
o Analogous situation arises when a strong acid and a weak
base are mixed
Strongest
Acid
Strength
Weakest
Perchloric acid
HClO4
ClO4-
Perchlorate
ion
Weakest
Acid
Strength
Strongest
Nitric acid
HNO3
NO3-
Nitrate ion
Hydrochloric acid
HCl
Cl-
Chloride ion
Sulphuric acid
H2SO4
HSO4-
Hydrogen
sulphate ion
Hydronium ion
H3O+
H2O
Water
Phosphoric acid
H3PO4
H2PO4-
Dihydrogen
phosphate
ion
Acetic acid
CH3COOH
CH3COO-
Acetate ion
Carbonic acid
H2CO3
HCO3-
Hydrogen
carbonate
Dihydrogen
phosphate ion
H2PO4-
HPO42-
Hydrogen
Phosphate
ion
Ammonium ion
NH4+
NH3
Ammonia
Hydrogen
cyanide
HCN
-CN
Cyanide ion
Hydrogen
carbonate ion
HCO3_
CO32-
Carbonate
ion
Methylammoniun
ion
CH3NH3+
CH3NH2
Methylamine
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Document Summary

Synthesis of copper compounds form metallic compounds: cu cu(no3)2 cu(oh)2 cuo cuso4 5h2o cu. Synthesis of copper (ii) nitrate and copper (ii) hydroxide: cu(s) + 4no3(aq) cu(no3)2(aq) + 2no2(g) +2h2o(l, cu(no3)2(aq) + 2naoh(aq) cu(oh)2(s) + 2nano3(aq) Synthesis of copper (ii) oxide: cu(oh)2(aq) cuo(s) + h2o(l) Synthesis of copper (ii) sulphate: cuo(s) + h2so4(aq) cuso4(aq) + h2o(l) Recovery of copper: cuso4(aq) + zn(s) cu(s) + znso4(aq, zn(s) + 2hcl(aq) Percent recovery: ( initial mass / recovered mass ) x 100% Experimental procedure: part 1: synthesis of copper (ii) nitrate and copper (ii) Obtain an length of copper wire and a piece of sandpaper, sand wire and weigh on analytical balance. Place copper wire in beaker in fume hood with 10 ml of. Nitric acid, let wire dissolve, bright blue solution. Dilute with 25ml of deionized water, stir in 25ml of. 20% naoh: part 2: synthesis of copper (ii) oxide.

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