Chemicals in Everyday Life

Experiment (4) Chemicals In Everyday Life Objectives: To identify the chemical constituents of some household items and some common chemicals. Introduction: It is important to know the composition of common substances at home and handle them safely. In case of an accident the fast action is important before taking the injured person to the hospital if it is needed, identification of substances can be done either by instruments or by chemical tests of identify some household items. Warning: "Never mix household chemicals unless you know what you are doing. Mixing chemicals sometimes produces explosion, fires, or other hazardous reactions". Procedure: A- Glass Cleaner, ammonia (NH3): It is dilute solution of ammonia, (NH3), which is tested by a red litmus paper. Hold a wet red litmus paper over a 100 ml beaker (or large test tube) containing household glass cleaner (ammonia). Record your observations. B- Fertilizers, ammonium salts : Some ordinary fertilizers contain ammonium compounds. Ammonium salts are converted to ammonia by strong bases: The familiar odor of ammonia could be noticed. The ammonia can be tested by a red litmus paper as described above. Hold a wet litmus paper over a test tube containing small amounts of solid fertilizer (0.5g), add 1ml of 8M NaOH solution to the test tube. Note the smell of the evolved gas by fanning the gas with your hand toward your nose. Record your observation. C- Table Salt, Sodium Chloride (NaCl): Table salt is mostly sodium chloride, Nacl. The test for Cl- is to convert it to HCl by strong acids, such as H2SO4, and the produced HCl is tested by blue litmus paper: Another test for Cl- is to convert it to a white solid AgCl by treatment with AgNO3(aq): Place about 0.5g of table salt in a test tube, add two drops of concentrated H2SO4 Solution. Note the smell of the gas. Test the gas by a wet blue litmus paper. Dissolve about 0.5g of NaCl in a test tube by adding 1ml of distilled water and a drop of 3M HNO3 solution, then add 4 drops of 0.1M AgNO3 solution. Record your observations. D- Baking Soda, sodium bicarbonate (NaHCO3); Lemon Juice, and Vinegar: Baking soda is sodium bicarbonate (NaHCO3), which is a basic salt that can be reacted with acids to form CO2(g): The CO2(g) evolved helps to raise the cake or dough. Lemon juice is simply citric acid, and vinegar is a dilute solution of acetic acid. Both acids react with baking soda. Place about 0.5g of baking soda in a test tube, add 1-2ml of lemon juice or vinegar. Record your observations. The test for escaping CO2(g) can be done by holding a drop of Ba(OH)2 solution at the tip of a dropper, and inserting the dropper down into mouth of the test tube. Clouding of the Ba(OH)2 drop is a proof for the presence of CO2(g) due to the formation of BaCO3(s): E- Bathroom Clearner, HCl: Most bathroom cleaners are dilute solution of HCl. Test form HCl in cleaners can be done by reacting the cleaner with limestone CaCO3, which will evolve CO2(g): The test for evolved CO2(g) can be done as described above (in part D). Place about 0.5g of limestone, CaCO3, into a test tube. Add 1-2ml of the bathroom cleaner, record your observations. F- Bleach, Cl2 / Water: Commercial bleach is a 5% solution of sodium hypochlorite, NaOCl. This solution behaves as though only chlorine, Cl2, were dissolved in water. Cl2(g) is a yellow green gas and it is considered as a strong oxidizing agent. It can be tested by oxidizing I- to I2 and I2 reacts with starch to form a dark blue complex: Dissolve 0.5g of NaI or KI in 1ml of distilled water, add drops of starch solution then add 5 drops of bleach. Record your observations. Warning: Bleach is a toxic material and has an irritating odor. Avoid direct contact with skin. G- Drain Opener, NaOH/AL: Drain opener is a mixture of solid sodium hydroxide and aluminum. When this mixture comes in contact with NaOH dissolves readily and reacts with AL to form H2(g): NaOH solution dissolves the solid fats that clogs the drain, H2 gas build up pressure which pushes wastes and dissolved fats down the drain. Place about 0.5g of drain opener in a test tube, add 5ml of warm water and shake well. Observe the formation of H2(g). Test form NaOH solution by a red litmus paper. Record your observations. H- Unknown: Receive an unknown solid from your instructor. The unknown contains one of the following ions: , or I-, Place a small amount of the unknown in a dray test tube and add a drop of 18 M H2SO4. Use the following table in determining the ion present in the unknown: Table (1): Reaction of solid salts with concentrated H2SO4. Ion Reaction Colorless, odorless gas, CO2 evolved. Cl- Colorless, pungent gas, HCl, evolve. No Reaction I- Violet vapors of I2 formed. Perform additional test to help in identification of the ion present. Observations: A- Glass Cleaner: 1- Change of litmus paper : ………………………………… 2- Reason for the change : ………………………………… B- Fertilizer: 1- Change of litmus paper : ………………………………… 2- Describe the smell of gas : ………………………………… 3- The smell is due to the formation of : ………………………………… C- Table Salt: 1- Describe the smell of the gas formed ………………………………… 2- The gas formed is……………… and it will turn a ……………… litmus paper into ……………… 3- When AgNO3 solution is added to the salt solution, a ……………… solid is formed which is ……………… D- Baking Soda: 1- Observation from the addition of lemon juice or vinegar to baking soda:……………… 2- Observation and equation of holding a drop of Ba(OH)2: …………………… E- Bathroom Cleaner: 1- Observation and equation of addition of the cleaner to limestone: …………….... F- Bleach: 1- Observation from the addition of bleach to KI solution and starch: The equation is ………………………………………………………………………… 2- The reaction is an oxidation-reduction, the element oxidized is:…………………. G- Drain Opener: 1- Observation from the addition to warm water to the drain opener: 2- The changes of litmus paper:………………………………………………………... H- Unknown: 1- Unknown No. is: …………………………………………………………………….... 2- Unknown Ion: …………………………………………………………………………… 3- Confirmatory tests: …………………………………………………………………...