Nature of Chemistry
Chemistry |
Study of substances that make up the world and the changes they undergo |
Pseydoscience |
Process inv. the collection of info that is supported by belief or opinion |
Science |
Process inv. the collection of info that is supported by evidence |
Science is systematic, inv. collection of info and ideas, inv. obs. and experimentation, supp. by evidence |
Science relies on process, is objective, is updated constantly |
Pseudoscience lacks process, is subject, is resistant to new info (i.e. flat earters..) |
Scientific inquiry is the process of using obs, investigations, and exp. to learn about natural phenomena -> any testable questions about obs., importance on creativity |
Formulating Scientific Questions
Scientific question |
Based on obs. and is testable |
Most Q are based on obs. |
What is that? Why? How does it work? I wonder why.. |
A good one |
narrow focus, unknown answer, addresses gap in knowledge, leads to a hypothesis that can be tested |
Non scientific question |
based on supernatural, opinion, rely on moral or social values |
Scientific methods
Dependent variable |
Variable that is changed by another variable |
Independent variable |
The variable that you change |
Qualitative |
Obs/data that is not measured on numbers/precise measurements |
Quantitative |
Obs/data based on numbers/precise measurements |
Sc. Inquiry |
Process of using obs, inv., and exp. to learn about natural phenomena |
Conclusion |
Summary of the results |
Controlled exp. |
an exp. in which one variable is changed |
Control sample |
Sample in a controlled exp. with variables that don't change |
Exp. sample |
sample in a controlled exp. in which one variable changes |
Models |
Simple, idea, picture, equation, method, diagram -> visualizing exp. results |
Writing a lab report |
Question/Hypothesis -> materials -> procedure -> results/data -> analysis -> conclusion |
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Research in Science
Skepticism |
Open minded knowledge in a certain area may be uncertain |
Bias |
Point of view influenced by opinion |
Scientific census |
General agreement along scientists on an idea |
How to develop sc. census? |
Communication! Publications (peer-reviewed), meetings/conferences, discuss findings (person/online) |
Databases |
Pubmed, NCBI, NHI, Google scholar |
Hypothesis, Theory, and Law
Hypothesis |
Testable expl. of a sc. problem based on research and obs. (if/then). Must be testable, supported/refuted by data |
Theory |
Hypothesis or a group of rel. hypothesis as true based on obs. and repetitive exp., must be testable, req. many exp. and confirmed data to overturn/modify, can be used for predictions or explanations |
Law |
Statement of facts generally accepted to be true, describes relationships in nature, but does not prov. explanation; can be used to predict events/exp. results, support. by all obs. and data, doesn't |
How to work with a Hypothesis? |
Attempt to explain an obs. or answer a Q -> test it -> if support, then data will agree with it -> if refute, then data will not agree, redo procedure or hypothesis -> continue evaluating data |
Dalton's Atomic Theory |
all matter is comp. of atoms, atoms cannot be made/destroyed during chemical reactions, all atoms of an element are identical, different elements have diff. kinds of atoms, chemical reactions occur through rearrangement of atoms |
Atomic Theory |
Explains law of conservation of mass |
Reproducibility leads to reliability |
Theory must be supported by all evidence, other scientists should get similar results, all experiment must be reproducible |
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Safety in Science
MSDS (material safety data sheet) |
Describes properties, handling, and emergency procedures of a substance |
General safety practices |
Avoid lose clothes/hair, wear long sleeves/close toed shoes, do not drink/eat/chew gum, no jewelry, avoid contacts if possible, avoid clutter in lab |
Handling chemicals/equipment |
Use tongs/mitts for hot objects, label all containers, inspect equipment before use, dispose of all substances appropriately |
PPE (personal protective equipment) |
Eyes/face: safety goggles/shield, skin/clothing: lab coat/apron, hands: gloves |
Emergency equipment |
Fire extinguisher, eye wash, safety shower, first-aid kit |
Chemistry glass ware |
Beaker, flask, test tubes, graduated cylinder |
Handling glass ware |
check for breaks/chips, use tongs/holders |
Heating devices |
Bunsen brenner/alcohol burner, hot plate |
Use of chemicals |
Use clear/accurate labels, do not taste/smell/touch chemicals, use pipettes to transfer liquids, do not put liquids back into storage container, refer to MSDS for storage/disposal/handling |
Accident |
Stay calm, report, avoid danger, spill kit, help injured |
Cuts from broken glassware |
apply pressure/flush |
Chemical burns/irritations/heat burns |
remove heat source/put out fire |
Inhalation of toxic chemicals |
Get fresh air/report |
Chemicals in eyes |
Eye wash (10-15 mins), report |
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Tools and Technology in chem
Balance |
Measure mass |
Beaker |
Holds liquids |
Buret |
Used to deliver specific volume, i.e. titrate volumes |
Degrees Celsius |
Fahrenheit - 30 : 2 = ~ x C |
Graduated cylinder |
Measure volume of liquid |
SI |
International system of units, standard set of units used by all scientists |
Kelvin |
SI unit for temperature in science, 0 C = -273.15 K |
Kilogram |
SI Unit for mass |
Liter |
SI unit for volume |
Meter |
SI unit for distance |
Metric conversion example
Collecting and organizing data
inference |
logical conclusion made from observation |
Qualitative data |
non-numerical, descriptive - describes categories or characteristics of things |
Quantitative data |
numerical data that can be measured, data that is easy to analyze over graph or table, has units, always numbers |
Charts |
Used for qualitative data |
Tables |
Used for numerical data set in columns and rows |
Graphs |
Bar/line/pie, display data for analysis |
Labels |
for all parts of charts, tables, and graphs |
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