Unit 1 Foundations of Chemistry – Expectations, Lab Safety, Measurement and Analysis

Nature of Science  Mystery Solutions Lab

3 The Nature of Science* Humans have need to:  Understand the world around them  Change their environment using technology  Natural curiosity vs. making life better Science always begins with observations ! Much of science is descriptive. Science uses both deductive and inductive reasoning. * Adapted from Next Generation Science Standards

4 The Nature of Science* Basic Understandings of Science 1. Scientific investigation uses a variety of methods (NOT just scientific method) 2. Based on EVIDENCE! 3. Scientific knowledge can change based on new evidence * Adapted from Next Generation Science Standards

5 The Nature of Science* Basic Understandings of Science 4. Use models, theories, laws, mechanisms to describe natural phenomenon 5. Assumes order in nature 6. Human’s “do” science 7. Addresses questions about the natural AND material world * Adapted from Next Generation Science Standards

Lab Safety

Why is Lab Safety Important?  Lab safety is a major aspect of every lab based science class.  Lab safety rules and symbols are needed so that students do not injure themselves or their classmates.

Lab Safety  Video  Demos  Why do you need to wear eye protection? I wear contacts?  What happens if I spill acid on my skin?  Why do I have to label materials?  Why shouldn’t I drink in the lab and why can’t I dump everything down the sink?

Why is Lab Safety Important?  Lab safety is a major aspect of every lab based science class.  Lab safety rules and symbols are needed so that students do not injure themselves or their classmates.

Lab Safety Rules 1. Always follow the teacher’s directions and only do lab work when a teacher is present. 2. Read instructions BEFORE starting experiments. 3. Do not touch any equipment, chemicals, or other materials until told to do so.

Lab Safety Rules 4. Do not eat food, drink beverages, or chew gum in the lab. 5. Do not use lab glassware as food or beverage containers 6. Keep hands away from face, eyes and mouth when using chemicals

Lab Safety Rules 7. Keep work areas clean & tidy 8. Keep aisles clear 9. Report ALL accidents to your teacher immediately, even if you think it is minor.

Lab Safety Rules 10. Wash hands thoroughly before leaving the lab.

Clothing Wear: Goggles/safety glasses Closed-toed shoes Clothing made of natural based fiber such as cotton Tie back long hair Do NOT Wear: Sandals Dangling Jewelry Loose or Baggy clothing

Safe Lab Procedures  When checking a chemical for odors, gently waft vapors towards nose;  Double check labels on chemical bottles  Take only as much chemical as you need;  Never return unused chemicals to their original containers;

Lab Safety Equipment Safety ShowerSafety Goggles Eye Wash

Lab Safety Equipment Fire Extinguisher Fire Blanket Fume Hood

Chemical Hazard Symbols and Definitions  Flammable – Any substance that will burn if exposed to an open flame.  Explosive – A substance that may explode if exposed to heat or flame.

Chemical Hazard Symbols and Definitions  Toxic/Poison – A substance that can lead to death if inhaled, ingested, or absorbed by the skin.  Corrosive – A substance that can destroy or burn living tissue and can eat away at other materials.

Chemical Hazard Symbols and Definitions  Irritant - A substance that causes inflammation upon contact with skin or mucous membranes.  Environmental - Substances that are harmful to the environment. They must be disposed of properly, not washed down the drain.

Accidents and Injuries  Again… Report ALL accidents and injuries to your teacher immediately!!!  Be aware of safety hazards associated with each chemical you use.  Eye accident – Wash the eye with copious amounts of water for at least 15 min.  Fire Burns – Stop, Drop, and be covered with a fire blanket or soaked with water. Do not remove clothing stuck to victim. Get medical attention immediately.

Waste Disposal  First ask your teacher where/how to dispose of waste.  Never pour anything down the drain unless you are told to do so. It can affect the community’s water, plants, animals & people.  A waste bottle will be supplied for substance that cannot go down the drain

Fire Drill  Why should I pay attention? Why should I pay attention?  Where do we go?  Class leader?

Lab Safety Continued  Lab Safety Contract  Lab Safety Crossword Puzzle

Any Questions?

Chemistry Lab Analysis

Lab Analysis  Chemistry labs are designed to investigate a problem or questions  Procedure designed  Data is collected.  Analysis section interprets the data

Lab Analysis  3 Tools for Lab Analysis:  1. Observation & Inferences  2. Accuracy & Precision  3. Graph Construction & Analysis

(I) Observation & Inference

Observations  Any information collected with the senses.  The skill of describing scientific events.

Observations 22 Types QQualitative observations = descriptive observations, no numbers involved (i.e. color, texture, smell) QQuantitative observations = observations described by a numbered measurement. (i.e. 5 meters, 30 seconds, 32 mL)

Inference  Conclusions or deductions based on observations *May be influenced by prior knowledge.  Process of drawing a conclusion from given evidence.

Tracks like these are common in parts of New England and in the southwestern United States. What do you OBSERVE? What can you INFER?

Now what do you think?

Infer what happened based on your observations.

Observation Activity #1  Observe the picture for exactly 30 seconds. Look at everything you think might be important.picture  After 30 seconds, answer the questions on the next page on a sheet of paper.  How observant were you? Compare your answers to the picture.

Questions: 1. Are there cars parked on the sides of the road? 2. What color is the pickup truck driving in the road? 3. Any minivans around? 4. What does the blue sign say? 5. What’s the speed limit? 6. Are there any pedestrians on the road?

Question 1 Are there cars parked on the side of the road?

Question 2 What color is the pickup truck driving in the road?

Question 3 Any minivans around?

Question 4 What does the blue sign say?

Question 5 What's the speed limit?

Question 6 Are there any pedestrians on the road?

Observation Activity #2  Observe the picture for exactly 30 seconds. Look at everything you think might be important.picture  After 30 seconds, answer the questions on the next page on a sheet of paper.  How observant were you? Compare your answers to the picture.

Questions: 1. How many cars were in the intersection? 2. Across the street, are there any parked cars on the side? 3. What is the color of the van in the intersection? 4. Are there any other potential witnesses? 5. What was the speed limit? 6. Was there anyone parked in the first parking spot?

Question 1 How many cars were in the intersection?

Question 2 Across the street, are there any parked cars on the side?

Question 3 What is the color of the van in the intersection?

Question 4 Are there any other potential witnesses?

Question 5 What is the speed limit?

Question 6 Was there anyone parked in the first parking space?

Accuracy & Precision Two important points in measurement

Accuracy Accuracy = the extent to which a measured value agrees with a standard value  Accuracy of a device/tool  Accuracy of reader

Example: Accuracy Who is more accurate when measuring a book that has a true length of 17.0 cm? Susan: 17.0 cm, 16.0 cm, 18.0 cm, 15.0 cm Amy: 15.5 cm, 15.0 cm, 15.2 cm, 15.3 cm

Precision Precision = the degree of exactness of a measurement that is repeatedly recorded. (smallest range of values) Which set is more precise? Susan: 18.2, 18.4, Amy: 17.9, 18.3, Tom: 16.8, 17.2, 19.44

Exit Quiz: Evaluate whether the following are precise, accurate or both. Figure #1 Figure #2 Figure #3

Experimental Results Accuracy and Precision Sean 2.56g Average:_________________ 2.37g Accurate:________________ 2.41g Precise: _________________ Morgan 3.12 Average:_________________ 2.11 Accurate:________________ 4.32 Precise: _________________ Doug 3.22 Average:_________________ 3.25 Accurate:________________ 3.27 Precise: _________________ If the true value of the mass is 3.10g, explain each students measurements in terms of accuracy and precision.

 Percent Error  Percent deviation from the true (actual) value  Measure of accuracy  Anything below 10% is acceptable as accurate. The closer to 0% the better! % error = l True – experimental l x 100 True

II. Percent Error Example: AA student measured the density of an object to be g/ml. The true density of the object is 2.699g/ml. What is the percent error of the experiment? Is the student accurate? ll g/ml – g/ml l x 100 = 7.040% error g/ml  Y Yes, student is accurate. AAnything below 10% is acceptable as accurate. The closer to 0% the better!

Why is it so important to be accurate and precise as a chemist? MMedicine – certain amounts can turn into lethal dosages WWork with flammable products TTo insure reproducible products (cosmetics, soap, hair products…) TTo insure quality of our environments (air and water quality)

(III) Graphing

2 Types of Graphs used in Chemistry Lab Line Graph  A line graph shows the relationship between your variables. Usually used to show how things change over time.

2 Types of Graphs used in Chemistry Lab Bar Graph  A bar graph is used to show a comparison of different trials or different experimental groups.