A Study of Chemical Changes - Design Journal Template化学变化设计杂志模板的研究.doc

A Study of Chemical Changes Name:_ Date Assigned:_Date Due:8/5/05This lab will not be accepted past the due date observe and record chemical changes. demonstrate the use of the names and formulas of common chemical compoundsIntroductionChemistry is a science that investigates changes in matter. In chemical changes, new substances are formed. Often qualitative data can help us to determine if a chemical change occurred. Such examples are a color change, a precipitate forming, or the evolution of a gas. A precipitate is a solid that is formed in a chemical reaction. Sometimes you must let the solid settle to observe the precipitate. You can easily determine if a gas evolves by noticing the bubbles. PurposeIn this lab, you will study some reactions of common chemicals contained in consumer products. You will observe the notable macroscopic changes these chemicals undergo. The essence of understanding chemistry is to infer from macroscopic changes the submicroscopic behavior of atoms and molecules.Safety Wear your safety glasses Use the pipets only for careful controlled delivery of liquids Use caution as you proceedMaterialsThe following solutions will be used:sodium hydrogen carbonate; NaHCO3blue dyesodium hydrogen sulfate; NaHSO4potassium iodide; KIphenolphthalein-phencalcium choride; CaCl2starchsodium carbonate; NaCO3ammonia; NH3sodium hypochlorite; NaOCllead(II) nitrate; Pb(NO3)2silver nitrate; AgNO3copper(II) sulfate; CuSO4sodium hydroxide; NaOHhydrochloric acid; HClEquipment test tubes test tube rack pipetteProcedureMix 20 drops of each of the following chemicals in your test tubes. Gently flick the bottom of each test tube to mix the chemicals. Write your qualitative data in the table below each chemical set.NaHCO3 +HClHCl + bluedyeblue dye +NaOCl, then a few drops HClNaOCl + KI, then a few drops starchKI + Pb(NO3)2Pb(NO3)2+ CaCl2CaCl2 + NaHSO4NaHSO4 + NaCO3NaHCO3 +phenphen +NaOHNaOH +AgNO3AgNO3 +NH3NH3 + CuSO4CuSO4 +NaHCO3Questions1. Color changes, the formation of a precipitate, and the evolution of a gas(bubbles) often tell that a chemical reaction took place. Write the names and formulas of each set that: 1. showed a color change/formed a precipitate2. a gas was released3. Sodium hydrogen carbonate is baking soda. When HCl is added to sodium hydrogen carbonate, carbon dioxide bubbles are formed. What is the formula for carbon dioxide? In what consumer product is this gas commonly found?4. Which of the other mixings form bubbles?5. What do you think the gas is that results from the mixing in question 4?6. The body uses hydrochoric acid, HCl, to help digest food. Where in the body is this acid found?7. A precipitate is a solid that separates upon mixing solutions. Which reaction produced a very bright yellow precipitate?8. Which mixture produced a precipitate that was very slow to form?9. What are three different kinds of observations that indicate that a che