HOW TO PREPARE FOR CHEMISTRY LAB?
Nbsp; Elmira Alimkulova, Nazira Mukhanbetova
EXPERIMENTAL LABORATORY MANUAL
By discipline GENERAL CHEMISTRY
For students of technical specialties
Astana 2015
CONTENTS
| Introduction | 3 |
| How to prepare for chemistry lab? | 5 |
| Safety in the laboratory | 5 |
| How to write a lab report? | 7 |
| Laboratory equipment and instruments | 9 |
| What is chemistry? | 15 |
| Si unit | 19 |
| Laboratory work «Chemical thermodynamics» | 24 |
| Laboratory work «Chemical kinetics» | 29 |
| Laboratory work «Solutions» | 38 |
| Laboratory work «Colligative properties of solutions» | 50 |
| Laboratory work «Ionic reaction» | 56 |
| Laboratory work «Salts hydrolysis» | 64 |
| Laboratory work «Water hardness» | 73 |
| Laboratory work «Redox reactions» | 80 |
| Laboratory work «Coordination compounds» | 86 |
| Laboratory work «Electrochemical cell types» | 103 |
| Laboratory work «Electrolysis» | 112 |
| Laboratory work «Metals» | 131 |
| Laboratory work «Metal corrosion» | 148 |
| Questions for the exam | 157 |
| Glossary | 160 |
| Literature sources | 167 |
INTRODUCTION
The study programs for scientific and technical degrees include classroom theoretical teaching, analysis and resolution of real exercises, and some more practical teaching in the laboratory. The laboratory teaching focuses on the application of the theoretical concepts and principles to practical cases, in order to complement the theoretical classes and to reinforce the understandability of the main theoretical concepts.
Commonly, the professor provides the students with a detailed recipe about what to do and how to do in the lab. The recipe contains the theoretical basis and the detailed description of the work in the lab in order to reach the desired result. However, there is different approach to the laboratory teaching. The professor can provide the student with the theoretical concepts and the practical tools to get the desired results without a detailed recipe. It makes the laboratory teaching more dynamic and creative. However, it implies more work for the professor and the student. The professor needs to supervise the work of the student more closely; and the student has to organize his/her work before to go to the lab.
Chemistry is the science of matter, its properties, and changes. In your classroom work in chemistry, you will learn a great deal of the information that has been gathered by scientists about matter. But, chemistry is not just information. It is also a process for finding out more about matter and its changes. Laboratory activities are the primary means that chemists use to learn more about matter. The activities in the Laboratory Manual require that you form and test hypotheses, measure and record data and observations, analyze those data, and draw conclusions based on those data and your knowledge of chemistry. These processes are the same as those used by professional chemists and all other scientists.
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Organization of Activities :
• Introduction: following the title and number of each activity, an introduction provides a background discussion about the problem you will study in the activity.
• Problem: the problem to be studied in this activity is clearly stated.
• Objectives: the objectives are statements of what you should accomplish by doing the investigation. Recheck this list when you have finished the activity.
• Materials: the materials list shows the apparatus you need to have on hand for the activity.
• Safety: precautions Safety symbols and statements warn you of potential hazards in the laboratory. Before beginning any activity, refer to page 23 to see what these symbols mean.
• Pre-Lab: the questions in this section check your knowledge of important concepts needed to complete the activity successfully.
• Procedure. The numbered steps of the procedure tell you how to carry out the activity and sometimes offer hints to help you be successful in the laboratory. Some activities have CAUTION statements in the procedure to alert you to hazardous substances or techniques.
• Hypothesis: this section provides an opportunity for you to write down a hypothesis for this activity.
• Data and Observations: this section presents a suggested table or form for collecting your laboratory data. Always record data and observations in an organized way as you do the activity.
• Analyze and Conclude. The Analyze and Conclude section shows you how to perform the calculations necessary for you to analyze your data and reach conclusions. It provides questions to aid you in interpreting data and observations in order to reach an experimental result. You are asked to form a scientific conclusion based on what you actually observed, not what “should have happened.” An opportunity to analyze possible errors in the activity is also given.
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• Real-World Chemistry. The questions in this section ask you to apply what you have learned in the activity to other real-life situations. You may be asked to make additional conclusions or research a question related to the activity.
When scientists perform experiments, they make observations, collect and analyze data, and formulate generalizations about the data. When you work in the laboratory, you should record all your data in a laboratory report. An analysis of data is easier if all data are recorded in an organized, logical manner. Tables and graphs are often used for this purpose.
Title: The title should clearly describe the topic of the report.
Hypothesis: Write a statement to express your expectations of the results and as an answer to the problem statement.
Materials: List of all laboratory equipment and other materials needed to perform the experiment.
Procedure: Describe each step of the procedure so that someone else could perform the experiment following your directions.
Results: Include in your report all data, tables, graphs, and sketches used to arrive at your conclusions.
Conclusions: Record your conclusions in a paragraph at the end of your report. Your conclusions should be an analysis of your collected data.
HOW TO PREPARE FOR CHEMISTRY LAB?
Chemistry lab is a required component of most chemistry courses. Learning about lab procedures and performing experiments helps you to learn techniques and reinforces textbook concepts. Make the most of your time in the lab by coming to lab prepared. Review these pre-lab tips before starting an experiment.
Complete any pre-lab assignments or homework. The information and calculations are intended to make the lab exercise quicker and easier.
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Know the location of the lab safety equipment and understand how to use it. In particular, know the location of the emergency exit, fire extinguisher, eye wash station and safety shower.
Read through the experiment before going to lab. Make sure you understand the steps of the experiment. Write down any questions you have so that you can ask them before starting lab.
Start filling out your lab book with information about the experiment. It's a good idea to draw out your data table in advance so all you need to do in lab is fill it in with numbers.
Review the Material Safety Data Sheets (MSDSs) of the chemicals you will be using during lab.
Make certain you have all of the glassware, materials and chemicals needed to complete the lab before starting any part of the procedure.
Understand disposal procedures for the chemicals and other items used in your experiment. If you are unclear about what to do with your experiment after it has been completed, ask your instructor about it. Don't throw items in the trash or dump liquids down the drain or in waste disposal containers until you are certain it is acceptable to do so.
Be prepared to take data in the lab. Bring your notebook, a pen and a calculator.
Have personal safety gear, such as a lab coat and goggles, clean and ready to use before lab.
SAFETY IN THE LABORATORY
The chemistry laboratory is a place to experiment and learn. You must assume responsibility for your own personal safety and that of people working near you. Accidents are usually caused by carelessness, but you can help prevent them by closely following the instructions printed in this manual and those given to you by your teacher. The following are some safety rules to help guide you in protecting yourself and others from injury in a laboratory.
1. The chemistry laboratory is a place for serious work. Do not perform activities without your teacher’s permission. Never work alone in the laboratory. Work only when your teacher is present.
2. Study your lab activity before you come to the lab. If you are in doubt about any procedures, ask your teacher for help.
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3. Safety goggles and a laboratory apron must be worn whenever you work in the lab. Gloves should be worn whenever you use chemicals that cause irritations or can be absorbed through the skin.
4. Contact lenses should not be worn in the lab, even if goggles are worn. Lenses can absorb vapors and are difficult to remove in an emergency.
5. Long hair should be tied back to reduce the possibility of it catching fire.
6. Avoid wearing dangling jewelry or loose, draping clothing. The loose clothing may catch fire and either the clothing or jewelry could catch on chemical apparatus.
7. Wear shoes that cover the feet at all times. Bare feet or sandals are not permitted in the lab.
8. Know the location of the fire extinguisher, safety shower, eyewash, fire blanket, and first-aid kit. Know how to use the safety equipment provided for you.
9. Report any accident, injury, incorrect procedure, or damaged equipment immediately to your teacher.
10. Handle chemicals carefully. Check the labels of all bottles before removing the contents. Readthe labels three times: before you pick up thecontainer, when the container is in your hand,and when you put the bottle back.
11. Do not return unused chemicals to reagent bottles.
12. Do not take reagent bottles to your work area unless specifically instructed to do so. Use test tubes, paper, or beakers to obtain your chemicals. Take only small amounts. It is easier to get more than to dispose of excess.
13. Do not insert droppers into reagent bottles. Pour a small amount of the chemical into a beaker.
14. Never taste any chemical substance. Never draw any chemicals into a pipette with your mouth. Eating, drinking, chewing gum, and smoking are prohibited in the laboratory.
15. If chemicals come into contact with your eyes or skin, flush the area immediately with large quantities of water. Immediately inform your teacher of the nature of the spill.
16. Keep combustible materials away from open flames. (Alcohol and acetone are combustible.)
17. Handle toxic and combustible gases only under the direction of your teacher. Use the fume hood when such materials are present.
18. When heating a substance in a test tube, be careful not to point the mouth of the tube at another person or yourself. Never look down the mouth of a test tube.
19. Use caution and the proper equipment when handling hot apparatus or glassware. Hot glass looks the same as cool glass.
20. Dispose of broken glass, unused chemicals, and products of reactions only as directed by your teacher.
21. Know the correct procedure for preparing acid solutions. Always add the acid slowly to the water.
22. Keep the balance area clean. Never weigh chemicals directly on the pan of the balance.
23. Do not heat graduated cylinders, burettes, or pipettes with a laboratory burner.
24. After completing an activity, clean and put away your equipment. Clean your work area. Make sure the gas and water are turned off. Wash your hands with soap and water before you leave the lab.
25. The below given table is helpfull in an accident situation. Read and remember them:
| Situation | Safe Response |
| Burns | Flush with ethanol solution or diluted solution of KMnO4. |
| Cuts and Bruises | Treat as directed by instructions included with first aid kit |
| Fainting or collapse | Provide person with fresh air, have him recline in a position so that his head is lower than their body |
| Foreign Matter in Eyes | Flush about 15 min with plenty of water, then go to the doctor |
| Severe bleeding | Apply pressure or a compress directly to the wound and get medical attention immediately |
| 1. Spills, general 2. Acid burns 3. Base burns | 1. Wash area with plenty of water, use safety shower if needed 2. Use sodium hydrogen carbonate (baking soda) 3. Use 3 % of boric acid or acetic acid |
HOW TO WRITE A LAB REPORT?
Lab reports are an essential part of all laboratory courses and usually a significant part of your grade. If your instructor gives you an outline for how to write a lab report, use that. Some instructors require the lab report be included in a lab notebook, while others will request a separate report. Here's a format for a lab report you can use if you aren't sure what to write or need an explanation of what to include in the different parts of the report.
A lab report is how you explain what you did in experiment, what you learned, and what the results meant. Here is a standard format. If you prefer, you can print and fill in the science lab report template or download the pdf version of the template.
Title Page. Not all lab reports have title pages, but if your instructor wants one, it would be a single page that states:
· The title of the experiment.
· Your name and the names of any lab partners.
· Your instructor's name.
· The date the lab was performed or the date the report was submitted.
Title. The title says what you did. It should be brief (aim for ten words or less) and describe the main point of the experiment or investigation. An example of a title would be: "Effects of Ultraviolet Light on Borax Crystal Growth Rate". If you can, begin your title using a keyword rather than an article like 'The' or 'A'.
Introduction / Purpose. Usually the Introduction is one paragraph that explains the objectives or purpose of the lab. In one sentence, state the hypothesis. Sometimes an introduction may contain background information, briefly summarize how the experiment was performed, state the findings of the experiment, and list the conclusions of the investigation. Even if you don't write a whole introduction, you need to state the purpose of the experiment, or why you did it. This would be where you state your hypothesis.
Materials. List everything needed to complete your experiment.
Methods. Describe the steps you completed during your investigation. This is your procedure. Be sufficiently detailed that anyone could read this section and duplicate your experiment. Write it as if you were giving direction for someone else to do the lab. It may be helpful to provide a Figure to diagram your experimental setup.
Data. Numerical data obtained from your procedure usually is presented as a table. Data encompasses what you recorded when you conducted the experiment. It's just the facts, not any interpretation of what they mean.
Results. Describe in words what the data means. Sometimes the Results section is combined with the Discussion (Results & Discussion).
Discussion or Analysis. The Data section contains numbers. The Analysis section contains any calculations you made based on those numbers. This is where you interpret the data and determine whether or not a hypothesis was accepted. This is also where you would discuss any mistakes you might have made while conducting the investigation. You may wish to describe ways the study might have been improved.
Conclusions. Most of the time the conclusion is a single paragraph that sums up what happened in the experiment, whether your hypothesis was accepted or rejected, and what this means.
Figures & Graphs. Graphs and figures must both be labeled with a descriptive title. Label the axes on a graph, being sure to include units of measurement. The independent variable is on the X-axis. The dependent variable (the one you are measuring) is on the Y-axis. Be sure to refer to figures and graphs in the text of your report.
References. If your research was based on someone else's work or if you cited facts that require documentation, then you should list these references.
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