Observations Experimental Procedure NAME Part 1

Transcription

1 1 Observations Experimental Procedure NAME Part 1 All scientific experimentation should be accompanied by careful and complete observations. These observations will often be the best medium available for discovering and understanding the principles that help us describe chemical systems. Your level of success in both the lecture and laboratory portion of this course can be enhanced if you learn this first lesson and apply it to the remainder of the course. Procedure 1. There are three stations to work through labeled A, B, and C. Start at any one of the stations and follow the directions for that station (given below). Record all your observations, neatly and completely, in the space provided below. You may cycle through stations A, B, and C in any order. (Note: ignore stations D, E, and F for now.) Instructions for Station A Reaction 1: Place one dropper full of Liquid A1 into a clean test tube, then add an equal amount of Liquid A2. Record your observations. Reaction 2: Place one dropper full of Liquid A3 into a clean test tube, then add an equal amount of Liquid A4. Record your observations. Dispose of the contents of both test tubes by washing them down the Station A observations: Instructions for Stations B and C on next page

2 2 Instructions for Station B Reaction 3: Place two droppers full of Liquid B1 into a clean test tube, then add one small piece of Solid B2. Record your observations. Reaction 4: Place one small scoop of Solid B3 into a clean test tube, fill the test tube one-third full with Liquid B4. Stir thoroughly for one minute. Record your observations. Dispose of any remaining solid from Reaction 3 in the trash can; everything else can be washed down the Station B observations: Instructions for Station C Reaction 5: Place one dropper full of Liquid C1 into a clean test tube, then add an equal amount of Liquid C2. Record your observations. Reaction 6: Place one dropper full of Liquid C3 into a clean test tube, then add one piece of Solid C4. Record your observations. Dispose of the contents from Reaction 5 in the indicated container (ask the instructor). Dispose of any remaining solid from Reaction 6 in the trash can; everything else can be washed down the Station C observations: 2. When you ve finished with stations A, B, and C, take your lab report sheet to the instructor to be initialed and get permission to begin the next part of the lab.

3 3 Observations Experimental Procedure NAME Part 2 Procedure 1. Read through the sheet Tips for Making Observations (on page 5). 2. After carefully reading the Tips for Making Observations, complete the lab by working through the three stations labeled D, E, and F. For each station, follow the directions given below. Record all your observations, neatly and completely, in the space provided below. You may cycle through the stations in any order. Be sure to use what you learned from the Tips for Making Observations! Instructions for Station D Reaction 1: Place one dropper full of copper nitrate into a clean test tube, then add an equal amount of ammonia. Record your observations. Reaction 2: Place one dropper full of iron chloride into a clean test tube, then add an equal amount of potassium thiocyanate. Record your observations. Dispose of the contents of both test tubes by washing them down the Station D observations: Instructions for Stations E and F on next page

4 4 Instructions for Station E Reaction 3: Place two droppers full of hydrochloric acid into a clean test tube, then add one small piece of magnesium metal. Record your observations. Reaction 4: Place one small scoop of ammonium nitrate into a clean test tube, fill the test tube one-third full with pure water. Stir thoroughly for one minute. Record your observations. Dispose of any remaining solid from Reaction 3 in the trash can; everything else can be washed down the Station E observations: Instructions for Station F Reaction 5: Place one dropper full of lead nitrate into a clean test tube, then add an equal amount of potassium iodide. Record your observations. Reaction 6: Place one dropper full of silver nitrate into a clean test tube, then add one piece of copper metal. Record your observations. Dispose of the contents from Reaction 5 in the indicated container (ask the instructor). Dispose of any remaining solid from Reaction 6 in the trash can; everything else can be washed down the Station F observations: 3. Complete the postlab exercise on page 6 and turn everything in before you leave.

5 5 TIPS FOR MAKING OBSERVATIONS 1. Do your observations contain references to all of the appropriate senses? Example: When the two clear, colorless [sight] liquids were mixed, the solution remained clear and colorless and the test tube became hot [touch]. A vapor was given off. 2. Do your observations contain descriptions of what was observed both before and after? Example: Two clear, colorless liquids [before] were mixed. A white solid was formed [after] which was suspended in a clear liquid. 3. Do your observations include any reference to the time factor? Example: A clear, viscous liquid was added to a purple solid. There was no immediate reaction; after a short delay, the mixture began to bubble. Second example: As soon as the two clear, colorless liquids were mixed, the resulting solution instantly turned bright green; a white precipitate then became visible and slowly sank to the bottom over the next 5 minutes. 4. Do your observations contain reference to the state (solid, liquid, or gas) of each substance? Example: Bottle A contains a clear, colorless liquid. Bottle B contains a clear, light blue liquid. When mixed, a clear, dark blue solution [liquid] formed. Second example: When the gray solid was placed in water, it remained on the surface, bubbles formed around the edges of the solid, and the solid gradually diminished in size until it was no longer visible. 5. Do your observations contain references to the names of the chemicals used? Example: The clear, colorless liquid silver nitrate was mixed with the clear, colorless liquid hydrochloric acid. A white solid formed which was suspended in a clear liquid.

6 6 Observations Postlab Exercise NAME 1. Look over your recorded observations. The reactions in Stations A and D were actually the same. The reactions in B and E were also the same, and the reactions in C and F were the same. Explain how your observations for A,B,C compare to those of D,E,F in terms of completeness and details. 2. What have you learned about recording useful observations as a result of having done this lab?