Lab 7
Chemicals in everyday life
Concepts
– Positive test
• A test that deteemines a type of reaction based on a
positive result.
– Can not detrmine based on a negative result
Part A
• Positive tests for NH3
• Warning! Ammonia is caustic
• Ammonia salts synthesises to ammonium
in water
1. NH3 + H2O
NH4 + OH-
Part A
• Positive tests for NH3
• Warning! Ammonia is caustic
• Ammonium salts decompose to ammonia
when there is a strong base
1. NH3 + H2O
NH4 + OH-
1. Read procedures for part A on page 68 and
fill out 1 –6 pg 73
Part A
• Determine if fertilizers and smelling salts
have ammonium in it by doing positive tests
for ammonia
Part B
• Warning H2SO4 and HCl causes severe
burns
Part B
• Positive tests for baking soda (NaHCO3)
austic
• Carbonates react with acids to produce
carbon dioxide
1. CO3-2 + H+
CO2 + H2O
Part B
• Do a positive tests for CO2 in baking soda
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Add a small amount of baking soda to a dry test tube
Using a beral pipette add 1 or 2 drops of 18 M sulfuric
acid
Note the color and odor of the escaping gas
Record observation and answer questions 7
Repeat procedure but use vinegar or acetic acid
Record observation and answer questions 8
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Warning fan the gas do not smell it!!
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Warning H2SO4 causes severe burns
Part B
• Determine if chalk contains carbon dioxide
by doing Positive tests for carbon dioxide
• carbon dioxide and barium Hydroxide
produces a white precipitate
1. CO2 + BaOH
BaCO3 (s) + H2O
Part B
• Determine if chalk contains carbon dioxide by doing
Positive tests for carbon dioxide
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Add a small amount of chalk to a dry test tube
Using a beral pipette add 1 or 2 drops of 2 M HCL
Note the color and odor of the escaping gas
Omit Barium Hydroxide
Record observation and answer question 9
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Warning fan the gas do not smell it!!
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Warning HCL causes severe burns
Part C
1. All Cl- salts react with sulfuric acid
(H2SO4) to produce HCl (g)
2.All Cl- salts react with silver nitrate
(AgNO3) to produce a white precipitate
AgCl (s)
1. 2Cl- + H2SO4
2HCl(g) + SO4-2
2. Cl- + AgNO3
NO3 + AgCl (s)
Part C
• Do a positive tests on table salt to test for
Chloride ions
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Add a small amount of salt to a dry test tube
Using a beral pipette add 1 or 2 drops of sulfuric acid
Note the color and odor of the escaping gas
Record observation and answer questions 10 and 11
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Warning fan the gas do not smell it!!
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Warning H2SO4 causes severe burns
Part C
• Do a positive tests on table salt to test for
Chloride ions
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Add a small amount of salt to a dry test tube
Add 15 drops of distilled water
Using a beral pipette add 1 drop of Nitric acid
Using a beral pipette add 3 drops of silver nitrate
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Record observation and answer questions 12 – 13
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Warning HNO3 causes severe burns
Part C
• Do a positive tests on Cl- ions in tap
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In a test tube add 2ml of tap water
Using a beral pipette add 1 drop of Nitric acid
Using a beral pipette add 3 drops of silver nitrate
Record observation and answer questions 14
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Warning HNO3 causes severe burns
Do not do procedures 15 or question 15
Part D
SO4 -2 ions reacts with Barium chloride
(BaCl2) to produce Barium sulfate BaSO4 (S)
1. SO4 -2 + BaCl2
BaSO4(S) + 2 Cl-
•Read procedures for part D on pg 70 and fill out 16-17on pg 73
Part D
• Positive tests for sulfates in Epson salt
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In a test tube add a small quantity of epson salt
Using a beral pipette add 1 or two drops of
Sulfuric acid
Record observation and answer question 16
• Warning Sulfuric causes severe burns
Part D
• Positive tests for sulfates in Epson salt
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In a test tube add a small quantity of epson salt
Add 1 ml of distilled water
Using a beral pipette add 1 or 2 drops of Nitric
acid
Using a beral pipette add 1 or 2 drops of
barium Chloride
Record observation and answer question 17
• Warning Sulfuric acid causes severe
burns
Part E (bleach)
NaOCl4- ion (bleach) acts like a Cl2
gas
Chlorine gas and Chlorine ion act very
differently from each other
Chlorine gas can convert iodide salts to
iodine giving water and reddish hue
Part E (bleach)
• Positive tests for Iodide Salts
NaOCl4 ion (bleach) reacts with iodine
salts to form iodine
(Cl2)(aq) + 2I-
(I2)(aq) + 2 Cl-
Part E (Bleach)
• Positive tests for chlorine in bleach
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In a test tube add a small quantity of Iodine salt
Add 1 ml of distilled water
Using a beral pipette add 5 drops of bleach
Add a few drops of mineral oil
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Record observation and answer question 18
• Warning Bleach is corrosive
Part E (iodide salts)
• Positive tests for Iodide Salts
iodide salts react with silver to form silver
iodide, a pale yellow precipitate
AgNO3 aq) + I-
(AgI)(s) + NO3-
Part E (iodide salts)
• Positive tests iodide salts
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In a test tube add a small quantity of sodium iodide
Add 1 ml of distilled water
Using a beral pipette add 1 drops of Nitric acid
Using a beral pipette add 3 drops of silver nitrate
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Record observation and answer question 19
• Nitric acid is corrosive
Part E (iodide salts)
• Must be done in hood
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In a test tube add a small quantity of sodium iodide
In the hood using a beral pipette add 1 drops of Slfuric
acid
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Record observation and answer question 20
• Sulfuric acid is corrosive
Part F (Unknowns)
• Determine the type of ion your is unknown is
based on the results of a positive test with
H2SO4 based on table 7.1 on page 71
• You solid unknown will contain one of
the following ions
– CO3 -2, Cl - ,SO4 -2 , I -
Part F (? ions)
• In a test tube add a small quantity of
your unknown compound
• Using a beral pipette add 1 drops of
Sulfuric acid
• Record observation and based on table
7.1 answer question 21
• Warning Sulfuric acid is corrosive
Due next week
• Pgs 73 – 74 omit page 75
• Pre Quiz on lab 8