Solved: LAB 4 - Temperature and Rates of Reaction
Purpose:
To understand the effect of temperature on rates of reaction.
Materials:
• data sheet
• 3 Alka-Seltzer tablets
• 3 small glasses
• access to hot and cold tap water
• ice
• cup
• spoon
• digital thermometer (with a temperature range of at least -20°C to 120°C
• stopwatch
Procedure:
Follow these instructions and keep a written record of precisely what you do and do not do. The record should be detailed enough that someone else could perform the same procedure just using what you have written. Remember that you will need to submit your record of your procedure as part of your report.
- Fill one glass half full with hot water from the tap (as hot as your faucet makes it, be careful!)
- Use a thermometer to measure and record the temperature of the water.
- Drop one Alka-Seltzer tablet into the beaker. (If you need to, break it in half, but be consistent and do the same thing for each experiment.)
- Measure the time required for the tablet to fully dissolve.
- Fill the second beaker half full with room temperature water. Use a thermometer to measure and record the temperature of the water.
- Drop one Alka-Seltzer tablet into the beaker. (If you need to, break it in half, but be consistent and do the same thing for each experiment.)
- Measure the time required for the tablet to fully dissolve.
- Fill a cup with water and ice and stir. (Make sure there is about half as much ice as water, we want this water to be cold! Pieces of ice still in the water are fine.) Use a thermometer to measure and record the temperature of the water.
- Drop one Alka-Seltzer tablet into the cup. (If you need to, break it in half, but be consistent and do the same thing for each experiment.)
- Measure the time required for the tablet to fully dissolve.
What Do I Need To Submit?
All of the following should be submitted at one time--DO NOT submit partial reports, they will not be accepted.
• Submit to your teacher a lab report of your procedure and the data you collected. Use paragraphs with complete sentences and proper English grammar. You do not need to submit your data collection sheets, those are for your own convenience, but the information you collected should be part of your report.
• Be sure to include the Analysis Questions in your Discussion part of your Lab Report.
Section 1: Introduction
Section 2: Materials and Methods
Section 3: Results
Section 4: Discussion / Analysis
• Also record any other conclusions you have reached. Use paragraphs with
complete sentences and proper English grammar. Remember to cite any sources you consult.
Analysis Questions:
How much faster was the reaction in the hot tap water than in the ice water? If we increased the temperature of the water to almost boiling and dropped in a tablet, what do you predict would happen in this reaction?
Propose three other changes to the water that you could try in a future experiment to change the rate at which the tablet dissolves.
Lab Report Format
Each of the sections below should be at least one paragraph long. Except in
graphically presented data (tables, graphs, etc.), use complete, grammatically correct sentences. Revisions of mistakes in grammar will be required to improve your grade.
Section 1: Introduction
NOTE: Write this section BEFORE you do the lab.
In this section, you explain why you are doing this experiment/activity (besides the fact that it was assigned to you). Try to think from the point of view of the teacher who assigned it. Obviously he or she is hoping you will learn something, or that some concept from the lessons will become more concrete to you. This section should include the following three main points:
- Purpose: What will this lab activity/experiment help you learn about?
- Hypothesis: What do you think will happen?
- Reasoning/Prior support for hypothesis: Why do you think this will happen? What have you learned that leads you to believe this will happen?
Section 2. Materials and Methods
This should be a precise narrative of everything you did. Write in the past tense as if you are telling the story of it (not giving directions). If this lab is an experiment, be sure you point out which parts of the experiment are the independent variables, dependent variables, and the control. Keep in mind that you should describe your process in enough detail that another scientist could “replicate” your procedure. Do not simply copy this from the assignment. If you made mistakes, missed a measurement, etc.these are important details, not failings that will bring down your grade. Be honest about them. Sometimes great discoveries result from mistakes.In this section do not tell your readings, or measurements. For example you could say, “The temperature was measured at 4:03, 4:09,4:21, and 4:30.” You should not say, “At 4:03 the temperature was 13degrees Celsius…” Save those measurements for the results section.
Section 3. Results
This is where you record all your times, temperature readings, measurements, observations, etc. Feel free to use a combination of text, tables, charts, pictures, graphs or any logical ways to present your results. Be sure if you use graphically presented data that each figure, table, etc. is labeled and referred to in the text that accompanies it. (Example: Graph 1shows the temperature readings increasing over time.) Keep the submission format in mind when you choose how to present your results.You may upload your lab report as a document in either .doc or .pdfformat, or use the submission box.
Section 4. Discussion/Analysis
In this section you will state whether your hypothesis was supported or refuted (never “proven” or “disproven”). You will also answer any analysis questions that are included in the assignment. If no analysis questions are included, consider the following questions:
- Were any of your results unexpected?
- Where there any shortcomings in your procedures?
- What could be causing what you observed to happen?
- What additional studies need to be done to further advance your purpose stated in the introduction?
- What did you learn?