Lab 7Chemicals 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

1. NH3 + H2O NH4

+ OH-

• Positive tests for NH3

• Warning! Ammonia is caustic

• Ammonia salts synthesises to ammonium in water

Part A

1. Read procedures for part A on page 68 and fill out 1 –6 pg 73

• Positive tests for NH3

• Warning! Ammonia is caustic

• Ammonium salts decompose to ammonia when there is a strong base

1. NH3 + H2O NH4

+ OH-

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

1. CO3-2 + H+ CO2 + H2O

• Positive tests for baking soda (NaHCO3) austic

• Carbonates react with acids to produce carbon dioxide

Part B

• 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

– Warning fan the gas do not smell it!!

– Warning H2SO4 causes severe burns

• Do a positive tests for CO2 in baking soda

Part B

1. CO2 + BaOH BaCO3 (s) + H2O

• Determine if chalk contains carbon dioxide by doing Positive tests for carbon dioxide

• carbon dioxide and barium Hydroxide produces a white precipitate

Part B

• 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– Warning fan the gas do not smell it!!

– Warning HCL causes severe burns

• Determine if chalk contains carbon dioxide by doing Positive tests for carbon dioxide

Part C

1. 2Cl- + H2SO4 2HCl(g) + SO4

-2

2. Cl- + AgNO3

NO3 + AgCl (s)

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)

Part C

• 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– Warning fan the gas do not smell it!!

– Warning H2SO4 causes severe burns

• Do a positive tests on table salt to test for Chloride ions

Part C

• 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

• Record observation and answer questions 12 – 13

– Warning HNO3 causes severe burns

• Do a positive tests on table salt to test for Chloride ions

Part C

• 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

– Warning HNO3 causes severe burns

• Do a positive tests on Cl- ions in tap

Do not do procedures 15 or question 15

Part D

1. SO4 -2 + BaCl2 BaSO4(S) + 2 Cl-

SO4 -2

ions reacts with Barium chloride (BaCl2) to produce Barium sulfate BaSO4 (S)

•Read procedures for part D on pg 70 and fill out 16-17on pg 73

Part D• Positive tests for sulfates in Epson salt

• 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

• 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

• 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

• 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

• 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

• Record observation and answer question 19• Nitric acid is corrosive

Part E (iodide salts)• Must be done in hood

• In a test tube add a small quantity of sodium iodide• In the hood using a beral pipette add 1 drops of Slfuric

acid

• 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