Scientific Process Skills

Objective 1: the student for at least 40% of instructional time, conducts laboratory and field investigations using safe and ethical practices

Objective 2: the student uses scientific methods to solve investigative questions

Objective 3: the student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom

Material Safety Data Sheet

The MSDS for a chemical is a document

that lists the manufacturer, physical

and chemical properties, health

hazards, precautions for safe handling, exposure

limits, first aid, and other hazard data

Hazard Possible Effects

Common Symbol

Corrosive Damages tissue or

surface on contact

Flammable Causes fires or ignition

(burns or ignites easily)

Radioactive Damages tissue by

removing electrons or

breaking bonds;

carcinogen

Toxic Can damage or kill by

exposure via inhalation,

skin contact, or ingestion

Laboratory Safety Rules and Equipment

1. Read and understand all safety rules and labels

2. Follow directions and use the equipment only as instructed

3. Locate the emergency exit and safety equipment, including the eyewash station, fire blanket, and fire extinguisher

4. Wear required safety equipment, such as safety goggles, apron, and gloves when instructed to do so

5. Tie back hair and loose clothing

6. When diluting, pour chemicals into water, not water into chemicals

7. Do not return unused chemicals to the container

8. Report all accidents, spills, and broken glass to the instructor

9. Avoid eating, drinking, or directly smelling chemicals

10. Point test tubes that are being heated away from you and others

11. Clean up your area, tools, and hands when done

12. Turn off equipment when finished

Scientific Investigation

Investigation Example

Descriptive Use a thermometer to measure the heat of a reaction

Comparative Use pH scale to compare the acidity of several liquids

Experimental Test the effect of temperature on the solubility of solutions

*Science includes the design and application of testable statements and predictions regarding natural phenomena. Scientific questions can be explored through different types of investigations.

Scientific Method

1. Begin with a well-defined question

2. Learn, research, and collect information about your question

3. Make a hypothesis, a prediction about what might happen. It is a statement (often if/then) that must be able to be tested (not just opinion).

4. Design and conduct an experiment to test your hypothesis. Change only the variable that you are testing.

5. Collect and organize observations in a table, graph, or any other means of visual presentation.

6. Evaluate the data and make inferences. Look for patterns and use models or mathematical approximations to describe the data.

7. Make a valid conclusion. Do the results support the hypothesis?

Types of Variables

Variable Description

Independent Variable that is manipulated during the

experiment; it is shown on the x-axis

(horizontal)

Dependent Variable that responds to changes in the

independent variable; its value is measured; it is

shown on the y-axis (vertical)

Controlled Variable that is held constant during the

experiment

Types of Observation

Observation Description

Quantitative Involves measurements such as mass,

temperature, and volume

Qualitative Uses descriptions such as color, clarity, and

precision

Laboratory Equipment Equipment Purpose

Beaker Holds liquids; a wide mouth cylindrical container

Burette Dispenses precise liquid amounts via a vertical tube

Balance Measures mass in grams

Erlenmeyer flask Holds liquids; conical base with a cylindrical neck

Graduated cylinder

Measures the volume of liquids

Pipette Transfers small amounts of liquids using a thin tube

Test tube Holds small amounts of chemicals

Thermometer Measures the temperature of a substance

Volumetric flask Holds liquids; conical base with a cylindrical neck with volume derivations drawn on

Explanations, Data Evaluation, & Representation

• We evaluate scientific explanations using evidence, logic, and investigations.

• We extract and consider information from different sources, like scientific journals, news reports, and marketing materials

• We formulate a hypothesis about what might happen; a prediction based on observations and can be repeatedly tested

• We develop theories based upon our tested data; a well-established inference, reliable explanation that has been tested by multiple people under varying conditions

• Example: the Big Bang Theory states that all the matter in the universe was once contained in a single subatomic particle which exploded and is continuing to expand, even today.

Explanations, Data Evaluation, & Representation

Term Description

Average/mean Sum of values divided by numbers of items

Precision Closeness of values to each other (repeatability)

Accuracy Closeness to the “true” or “correct” value

Percent error (accepted value - experimental value) (100) accepted value

High precision, low accuracy High accuracy, low precision

Rules to determine the number of significant figures:

• For scientific notation, all digits of coefficients are

significant

• For “regular” numbers:

– Non-zero digits are significant

– Zeros between non-zero digits are significant

– Zeros both to the right of the decimal point and also to

the right of a non-zero digit are all significant

– Leading zeros are NOT significant

*Examples: significant figures 14 2 sig.figs. 32,000 2 sig.figs. 14.03 sig.figs 3.081x105

4 sig.figs. 0.0091 sig.fig. 2.00x10-9

3 sig.figs. 1.0094 sig.figs. 2x10-9 1 sig.fig.

Mathematic Operations With Significant Figures

Operation Significant Figures in Answer Example

Addition / Subtraction

Limit the answer to smallest place value on least precise number you began with

5.01 + 1.001 = 6.01

(3 sig.figs.)

Multiply / Divide

Limit the answer to the least number of significant figures that you started with

1,200 x 0.245 = 290

(2 sig.figs.)

Dimensional Analysis

• Method to convert units using equivalent values in different units

• Place one value in the numerator and the equivalent value in the denominator (the fraction’s value is now 1)

• Multiply this fraction to convert a value to different units

• Carefully write out all units to check your work

• Example:

– There are 760mmHg in 1atm; so 760mmHg/1atm = 1 or 1atm/760mmHg = 1

– How many mmHg is 0.89atm?

0.89atm x 760mmHg = 680mmHg

1atm

International System (SI) Units

kilo(k) hecto(h) deka(da) base deci(d) centi(c) milli(m)

1,000 Base units

100 Base units

10 Base units

1 Base unit

0.1 Base unit

0.01 Base unit

0.001 Base unit

Metric (SI) system: uses metric (SI) prefixes that represent powers of 10

larger unit smaller unit

*Smaller prefix values include micro (μ) = 10-6 and nano (n) = 10-9

Conversions and Constants

Unit Conversions

• It takes more of the smaller unit to equal the larger unit

• Use equivalent values of the initial and final units to find a unit of conversion factor (fraction’s value is 1)

• Multiply by this fraction to convert between units

Metric (SI) Conversions

• Set up a proportion using the metric prefix values discussed earlier

• If using scientific notation, keep the coefficient the same and change only the power of ten

Example: A wave travels 2.4 meters each second. How far will it travel in one hour? 2.4m x 60s x 60min = 8.6x103m/hr 1 s 1min 1hr

Examples: Convert 55.1mL to kL. 55.1mL x __1L__ x _1kL__ = 5.51x10-5kL

1000mL 1000L

End of Objective 1,2,3 notes