Introduction to Science

Introduction to Chemistry

CHEMISTRY = the study of the composition of matter, its chemical and physical changes, and the changes that accompany these changes.

DEMO: THINK TUBEThe Nature of ScienceScientific law versus theory:

Scientific law: a summary of an observed natural event.

Scientific theory: a well tested, possible explanation of a natural event.The Way Science WorksScience involves critical thinking, or applying logic and reason to observations and conclusions.

Observation vs. InferenceObservation: descriptive of what you see, hear, taste, feel, smellInference: an assumption made as a result of an observation (not always correct!!)

Variables and ControlsA variable is anything that can change in an experiment.

Independent variable: The variable being changed or controlled by the scientist.Dependent variable: The variable being measured or observed by the scientist.

A controlled experiment tests only one variable at a time.

The Scientific Method:A series of logical steps to follow in order to solve problems.OBSERVEFORMULATE A QUESTIONFORM A HYPOTHESISDESIGN AND CONDUCT AN EXPERIMENTMAKE OBSERVATIONSRECORD AND ANALYZE DATADRAW CONCLUSIONSFORMULATE NEW QUESTIONS and CONTINUE CYCLEDEMO: ON THE LEVEL

Making MeasurementsMeasurements are made in this class using SI units.

LENGTH (m): distance between 2 points

VOLUME (L): space occupied.

MASS (kg): the amount of matter in an object.

WEIGHT (N): the force with which gravity pulls on a quantity of matter.

Accuracy vs. PrecisionAccuracy: the extent to which a measurement approaches the true value.Precision: the degree of exactness of a measurement. A scale may be precise to the nearest 100th of a gram, or +/- 0.01g

Precision vs. Accuracyincreasing accuracyincreasing precision

DEMO: COKE vs. DIET COKEDensity = mass/volumeExample:What is the mass of 10 mL of a liquid that has a density of 3.76 g/mL?

d = m / v m = dvm = (3.76 g/mL)(10 mL)m = 37.6 gm = 40 g (correct # of sig. figs.)

MDVCalculationsCalculate the density of each:A can of Coke has a volume of 355 mL and a mass of 394 g (assuming that the weight of the aluminum can is constant)

A can of Diet Coke has a volume of 355 mL and a mass of 355.1 g (assuming that the weight of the aluminum can is constant)WHY is Diet Coke less dense?There is less mass in the same volume (355 mL)Coke has 39 grams of sugar in it to sweeten it (355 + 39 = 394 g)Diet Coke only needs 0.1 g of Nutra Sweet to make is just as sweet as Coke (355 + 0.1 = 355.1 g)

Temperature ConversionsTemperature is a measure of the average kinetic energy in a system.

K = KelvinoF = degree FahrenheitoC = degree CelsiusR=Rankin (we wont use this one in this class)Temperature ConversionsK = oC + 273

oF = (1.8 x oC) + 32

oC = (oF 32) / 1.8

Percentage ErrorCalculate this value in labs where the accepted value is given.

Graph - visual representation of data1) title2) x and y axis labeled3) units for both the x and y axis4) scale is evenly and correctly spaced for data5) legend when appropriate

GRAPHING...Organizing DataData is organized and presented in tables, charts, and graphs.LINE GRAPH: best for displaying data that change.Independent Variable: x-axisDependent variable: y-axis

LINEGRAPHBAR GRAPH: useful when you want to compare data for several individual items

BAR GRAPHS

PIE CHART: ideal for displaying data that are parts of a whole.PIE CHARTS

DEMO: MAGIC BUBBLEChart1273273273293313333353373373373393413433

Temperature (K)Time (sec)Temperature (K)Temperature Increase of a Beaker of Water

Sheet1Time (sec)Temperature (K)0273302736027390293120313150333180353210373240373270373300393330413360433

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Temperature (K)Time (sec)Temperature (K)Temperature Increase of a Beaker of Water

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Chart33002331079857

Number of Deaths per 100,000 PeopleNumber of Death's per 100,000 PeopleLeading Causes of Death in 2000

Sheet1Time (sec)Temperature (K)0273302736027390293120313150333180353210373240373270373300393330413360433Favorite TV ShowPercentFriends45%Will and Grace30%Frasier20%Dawson's Creek4%Other1%Leading Causes of Death in 2000Number of Deaths per 100,000 PeopleHeart Disease300Cancer233Diabetes107Accidents98Homicide57

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Temperature (K)Time (sec)Temperature (K)Temperature Increase of a Beaker of Water

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PercentFavorite Television Shows among Teens

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Number of Deaths per 100,000 PeopleNumber of Death's per 100,000 PeopleLeading Causes of Death in 2000