chem ex 1

Exact number

Is a number that has a value with no uncertainty in it; that is, it is known exactly. Definition: 12 objects in a dozen Counting: there are 7 people in my room Simple fractions: 1/3 1/2 3/5 5/9

Accuracy

Is an indicator of how close a measurement (or the average of multiple measurements) comes to a true or accepted value. The true value of for a measurement is the most accurate currently known value for a measured quantity

scientific theory allows

It allows scientists to predict what will happen in yet-to-be-run experiments.

scientific laww

It is a generalized summary of facts about a natural phenomenon

seven base units in the si system of units

Length meter m Mass kilogram kg Time second s temperature kelvin K Amount of substance mole mol Electric current* ampere A Luminous intensity* candela cd

si unit of speed =

SI unit of length (m) ___________________________ SI unit of time (s)

Scope of chemistry

Principles are fundamental to understanding all processes of living state. Chemical processes produce the products needed for our clothes housing transportation medications and recreational pursuits.

Systematic error

A constant error associated with an experimental system itself. Ex. Is incorrect calibration of an instrument A flaw in a piece of equipment Or presence of an interfering substance within the experimental system. Affects the accuracy of measurements but not the precision

Mass

A gram is a small unit compared to a pound. 1 gram = 1/454 pound Two pennies have a mass of about 5 grams

Volume

A liter is slightly larger than a quart. 1 liter = 1.06 quarts Most beverages are now sold by the liter rather than by the quart

inexact numbers

A number that has a value with a degree of uncertainty in it.. anytime a measurement is made it is an in exact number. Can never be exact with measurements. Because of Flawed in measuring device construction Improper calibration of of an instrument Skills of person using measuring device These all contribute to error or uncertainty Two important factors of uncertainty are precision and accuracy

percent error

the ratio of the difference between a measured value and the accepted value for the measurement and the accepted value itself, all multiplied by 100. equation= (measured value - accepted value)/accepted value x 100 can be positive or negative if measured value is greater than the accepted value, the difference will be positive. & percent error positive. if measured value is less than accepted value, the diff. will be negative & percent error negative. usually round to the whole number so (-3, 3, 1, 2, -2, etc.)

science

the study in which humans attempt to organize and explain in a systematic and logical manner knowledge about themselves and their surroundings.

biological sciences

the study of living organisms botany and zoology (plants and animals) (also biochem)

physical sciences

the study of matter and energy astronomy geology physics chemistry (also biochem) astrochemistry geochemistry chemical physics

instrumentation

used to aid for observations in an experiment.

negative exponents

when number 10 is rasied to a negative power, always one more than the number of zeroes between the decimal point and the one. so 10^-2 would be written as .01 so between decimal and one is one zero because one less than two is one. 10^-6 would be .000001 because one less than 6 is 5 and there are 5 zeroes between the decimal and the one.

Conversion Factors from DEFINED Relationships

• All English-to-English and metric-to- metric conversion factors • Have an unlimited number of significant figures 12 inches = 1 foot (exactly) 4 quarts = 1 gallon (exactly) 1 kilogram = 103 grams (exactly) Metric-to-metric conversion factors are derived using the meanings of the metric system prefixes.

Conversion Factors from MEASURED Relationships

• All English-to-metric and metric-to- English conversion factors • Have a specific number of significant figures, depending on the uncertainty in the defining relationship 1.00 lb = 454 g (three sig figs) 1.000 lb = 453.6 g (four sig figs) 1.0000 lb = 453.59 g (five sig figs)

New scientific law steps

1. A number of alternative scientific hypotheses are proposed to explain the new scientific law 2. Experiments are carried out to eliminate invalid scientific hypotheses 3. Predictions are made based on the surviving scientific hypothesis and further experiments are carried out to test these predictions 4. Confirmed predictions produce a validated scientific hypothesis 5. Many more validating experiments give the scientific hypothesis the status of a scientific theory.

Possible outcomes for experiment designed to test a scientific theory

1. Results disprove the scientific theory: modification of the scientific theory occurs and experimentation to disprove the modified theory begins 2. Results fail to disprove the scientific theory: new experiments to again try to disprove the scientific theory begin Experimentation to disprove a theory is never completed as a process. But after many failed attempts to disproves experimentation slows down and theory becomes a foundation of the scientific discipline.

uncertainty in a measurement

1. human error - a person's hands have limits as to how well they can manipulate laboratory equipment and a person;s eyes can see (read) only so well. there are limits to how well a person can calibrate an instrument. 2. instrument error - instruments themselves can have imperfections (flaws) associated with their manufacture. proper calibration of an instrument does not always negate such manufacturing defects. corrosion problems as well as wear and tear on a heavily used instrumental can also contribute to instrument error.

two types of information must be conveyed whenever a numerical value for a measurement is recorded

1. the magnitude of the measurement and 2. the uncertainty of the measurement. the magnitude is indicated by the digit values. the uncertainty is indicated by the number of significant figures recorded.

when changing temperature reading on one scale to its equivalent on another scale, 2 factors:

1. the size of the unit on the two scales may differ 2. the zero points on the two scales do not coincide.

scientific discipline

a branch of science limited in size and scope to make it more manageable. examples: chemistry astronomy botany geology physics and zoology

Area

a measure of the extent of a surface. The units for area are squared units of length Note that a squared unit is just that unit multiplied by itself. The unit cm2 means centimeter * centimeter in the same way that 32 means 3 * 3

exponent

a number written as a superscript following another number and indicates how many times the first number, the base, is to be multiplied by itself. exponents = powers of numbers.

scientific theory

a scientific hypothesis that has been tested and validated over a long period of time. dividing line between hypothesis and theory isnt rigid. theres no set number of experiments that must be reached or successful to become a theory. 1) they allow scientists to predict what will happen in experiments that havent been run 2) they simplify problem of being able to remember all scientific facts that have already been discovered. refers to the best idea thus far - subject to change.

scientific method

a set of general procedures based on experimentation and observation used to acquire scientific knowledge and explain natural phenomena. 1. identify problem, break it into small parts, and carefully plan procedures to obtain info about all aspects of problem 2. collect data concerning problem thru observation and experiments 3. analyze and organize the data in terms of general statements that summarize experimental observations 4. suggest probable explanations for the generalizations 5. experiment further to prove/disprove the proposed explanations. ICASE identify collect analyze suggest experiment

orders of magnitude

a single exponential value o the number 10. thus 10^6 is four orders of magnitude larger than 10^2.

experiment

a well-defined controlled procedure for obtaining info about a system under study.

basic scientific research

research whos major focus is the discovery of new fundamental information about humans and other living organisms and the universe in which they live. small # of researchers

applied chemical research

research whose major focus is the discovery of products and processes that can be used to benefit humankind.

both of these are correct orders

scientific law, scientific hypothesis, scientific theory scientific fact, scientific law, scientific hypothesis book order scientific fact, law, hypothesis, theory is order. so it doesn't matter if one gets skipped

correct

scientific theory and validated scientific hypothesis scientific law and unvalidated scientific hypothesis fact and valid observation

scientific fact

single observed situation. "the burning candle generated both heat and light" "as a candle burns, its wax gradually disappear" individual pieces of new information or data about a system under study obtained by carrying out experimental procedures. It is a reproducible piece of data about some natural phenomenon that is obtained from experimentation. (REPRODUCIBLE). if given experiment, will have the same results. must be verifiable by anyone who has time means and knowledge to repeat experiments. must be published so can be critiqued

experiment usually involves

study of atleast 2 quantities - or variables, that have changing values. usually effect of change in 1 variable on another variable, with all other variables held constant is measured. usually is performed under controlled conditions in which values always noted not just ones that are changing so it can be reproduced when needed.

technology

the application of applied chemical research to the production of new products to improve human survival, comfort, and quality of life. useful for beneficial or detrimental purposes depends on motives of those men and women whether in industry or govt. who have decision making authority. citizens in democratic society can influence technological decision (voting) cocaine used in medicine vs. illegally on the streets

Measurement

the determination of the dimensions, capacity, quantity, or extent of something. In chemical laboratories most common are mass volume length time temperature pressure and concentration How much how long how many

significant digits

the digits in any measurement that are known with certainty plus one digit that is uncertain - actually measured obtain from a measuring device report exactly as read from the measuring device number of significant figures = all certain digits + one uncertain digit

scientific law

"generalization" "all burning candles generated heat and light" (keyword = all) major goal of basic scientific research is to organize scientific facts so that their relationships can be established among them. scientific law is a generalization that summarizes scientific facts about a natural phenomenon. not easy to discover. thousands of facts and years before true relationships are determined. no new understanding, just describes observations that already exist or occur. can be expressed as a verbal statement or mathematical equation. key word "always" discovered by research and have no control over what it turns out to be. unlike arbitrary conventions - opposite.

All measurements consist of three parts:

(1) a number that tells the amount of the quantity measured, (2) an error that produces an amount of uncertainty, and (3) a unit that tells the nature of the quantity being measured

The cubic meter

(m3 ) is the SI system unit of volume. It is a derived SI unit rather than a base SI unit 1 cubic meter = volume of a cube with sides of 1 m =1 m * 1 m * 1 m = 1 m3 More frequently used than the preceding SI units of volume (m3 , dm3 , and cm3 ) are the non-SI units liter (L) and milliliter (mL). The abbreviation for liter is a capital L rather than a lowercase l because a lowercase l is easily confused with the number 1. (As with meter, we will use the U.S. spelling for liter rather than the international spelling, which is litre.)

milliliter

1 milliliter = 0.001 dm3 1 milliliter = 1 cm3

Precision

An indicator of how close a series of measurements on the same object are to each other. Must involve multiple measurements.

Scientific facts cerified

By repeated experiments never change Theories to explain are subject to change Facts > theories

random error

Error caused by uncontrollable variables in an experiment. Can be momentary changes in air currents or temperature. A variation in the angle from which a measurement scale is viewed. Precise measurements are an indication of minimal random error. Can have accurate measurements in which high random error is present if the highs and lows balance each other to prove an average that is close to the true measurement value.

General steps in scientific method

Experiments results (facts) scientific law scientific hypothesis further experiments devised based on scientific hypothesis Negative results modify or reject hypothesis Positive results means it's scientific theory Further experiments Positive means support scientific theory Negative means modification or qualification of scientific theory

No theory can ever be proved correct by experiment

Experiments can only provide supporting data for a theory but always chance that new experiments will negate theory.

Invalidated hypothesis

I have a theory that such and such is the case in everyday language. It is more a speculative guess. Theory is misused by nonscientists

chemical processes examples

Many of the clothes we wear are made from synthetic fibers produced by chemical processes. Even natural fibers, such as cotton or wool, are the products of naturally occurring chemical reactions within living systems. Our transportation usually involves vehicles powered with energy obtained by burning chemical mixtures such as gasoline or diesel and jet fuels. The drugs used to cure many of our illnesses are the result of chemical research. The paper on which this textbook is printed was produced through a chemical process, and the ink used in printing the words and illustrations is a mixture of many chemicals. Almost all of our recreational pursuits involve objects made of materials produced by chemical industries. Skis, boats, basketballs, bowling balls, musical instruments, and television sets all contain materials that do not occur naturally, but are products of human technological expertise. Our bodies are a complex mixture of chemicals. The principles of chemistry are fundamental to an understanding of all processes of the living state. Chemical secretions (hormones) produced within our bodies help determine our outward physical characteristics such as height, weight, and appearance. Digestion of food involves a complex series of chemical reactions. Food itself is an extremely complicated array of chemical substances. Chemical reactions govern our thought processes and how knowledge is stored in and retrieved from our brains. In short, chemistry runs our lives.

Mass & weight

Mass is a measure of the total quantity of matter in an object. Weight is a measure of the force exerted on an object by gravitational forces The mass of a substance is a constant; the weight of an object is a variable dependent upon the geographical location of that object

liter cubic decimeter milliliter and cubic centimeter units

Thus, the liter and cubic decimeter units are the same, and the milliliter and cubic centimeter units are the same

Which of the following statements concerning conversion factors is correct?

a. English-to-English conversion factors come from defined relationships (no) b. Metric-to-metric conversions come from measured relationships (no) c. English-to-English conversion factors always contain exact numbers d. more than one correct response e. no correct response ANSWER: c

false WRONG

a. English-to-English conversion factors come from measured relationships. b. Metric-to-English conversion factors come from defined relationships.

Which of the following statements are examples of a scientific hypothesis?

a. The metal gold is a solid at room temperature. b. The metal gold is yellow in color because of air bubbles always present in its structure. c. The metal gold has a density greater than that of the metal silver. answer is B because it has the word because it is a hypothesis

Which of the following concepts applies to both scientific hypotheses and non-scientific hypotheses?

a. can be tested using experimental methods b. pertains only to substances that can be seen c. offers an explanation for several observations d. more than one correct response e. no correct response c. offers an explanation for several observations

chemistry subdisciplines (branches)

analytical (analysis and composition) general (fundamental laws concepts) inorganic (noncarbon) organic (carbon containing) physical (energy changes)

significant figures

are the digits in any measurement that are known with certainty plus one digit that is uncertain. number of significant figures = all certain digits + one uncertain digit

scientific research

basic activity thru which new knowledge is added to the various scientific disciplines, including chemistry, is that of scientific research. the process of methodical investigation into a subject in order to discover new information about the subject.

is often necessary to change measurements from the English system to the metric system or vice versa. The mathematical tool used to accomplish this task is a general method of problem solving called is a general problem-solving method in which the units associated with numbers are used as a guide in setting up calculations

dimensional analysis

scientific hypothesis

ex. "burning candles generate heat as the result of the decomposition of melted wax" WHY a scientific law happens. plausible, tentative explanations of the behavior incorporated in scientific law. a model or statement that can be tested by experiment, which offers an explanation for a scientific law. testability. philosophy hypotheses are not scientific because they can't be tested. after proposal of this, experimentation begins again. run tests under varied but controlled conditions to test reliability of proposed explanation or hypothesis. must be able to predict outcome of as of yet. validity based on predictions being true.

chemistry is an

experimental science. most discoveries are made by the analysis of data obtained from experiments in labs.

inductive reasoning

general conclusions and is used to form hypotheses

uncertainty examples

if its one unit digits than its uncertainty goes to tenths if its ten unit intervals the uncertainty is 1 (10, 20) if its one unit with slivers than its hundredths. (29 to 30 is 29.25)

English system

inch, foot, pound, quart, and gallon

Volumee

is a measure of the amount of space occupied by an object. It is a three dimensional measure and thus involves units that have been cubed: in.3 , ft 3 , m3 , cm3 , and so on. Again, a cubed unit is just that unit multiplied by itself three times in the same manner that 33 is 3 * 3 * 3

si system of units

is a particular choice of metric units that was adopted in 1960 as a standard for making metric system measurements. The acronym SI comes from the phrase "French Systeme International d'Unites."

equivalence conversion factor

is a ratio that converts one type of measure to a different type of measure Density involves mass and volume, two different types of measure. density uses equivalence conversion

equality conversion factor

is a ratio that converts one unit of a given measure to another unit of the same measure. Twelve inches and one foot, which are both measures of length, generate an equality conversion factor ratios in which numerator and denominator involve the same measure

conversion factor

is a ratio that specifies how one unit of measurement is related to another unit of measurement Note that conversion factors always come in pairs, one member of the pair being the reciprocal of the other. Also note that the numerator and the denominator of a conversion factor always describe the same amount of whatever we are considering. One minute and 60 seconds denote the same amount of time

observation

is a statement that describes something we see, hear, smell, taste, or feel

liter

is a volume equal to that of a cube whose sides are 1 dm or 10 cm (1 dm = 10 cm) in length. 1 liter = 1 dm3 (1 dm * 1 dm * 1 dm) 1 liter = 1000 cm3 (10 cm * 10 cm * 10 cm)

SI-derived unit

is an SI unit derived by combining two or more SI base units.

Length

is measured by determining the distance between two points.

exact number in a multiplication problem

is not considered in significant figures, so look at the number with decimal places and pick the one that has the least amt. ignore the whole, exact number.

about 200 gummy bears

is qualitative because it is not exact - it is an estimate

exponential term

is the 10^4 that whole thing

meter

is the SI system base unit of length 1 meter equals 1.09 yards The kilometer (km) is 1000 times larger than the meter; the centimeter (cm) and millimeter (mm) are, respectively, one-hundredth and one-thousandth of a meter A meter is slightly longer than a yard. 1 meter = 1.09 yards A baseball bat is about 1 meter long.

kilogram (kg)

is the SI system base unit of mass It is the only SI base unit whose name includes a prefix (kilo- in this case). A gram is a very small unit compared with the English pound and ounce (Fig. 3.2b). It takes approximately 28 grams to equal 1 ounce and nearly 454 grams to equal 1 pound. Both grams (g) and milligrams (mg) are commonly used in the laboratory, where the kilogram (kg) is generally too large.

Percent

is the number of items of a specified type in a group of 100 total items.

Density

is the ratio of the mass of an object to the volume occupied by that object; that is, density (d) = mass/volume The SI-derived unit for density is kilograms per cubic meter (kg/m3 ). This is too large a unit for almost all chemical applications that involve density use.

metric system

is used in scientific work. Units in this system include the meter and kilogram

ACS (American chemical society)

largest scientific organization in the world. 33 subdivisions.

deductive reasoning

makes specific conclusions tests hypotheses

temperature

measure of the hotness or coldness ob an object. most common instrument is mercury-in-glass thermometer. degrees are defined units to indicate height of mercury or temp. si unit = kelvin (K) celsius: boiling = 100 and freezing = 0 kelvin has same size unit as celsius so same number of interals but diff. numbers. kelvin boiling = 373.15 k freeing is 273.15 k kelvin = negative temperature never occurs. lowest is 0, which is called absolute zero. fahrenheit difference between boiling and freezing is 600 equal degrees. water freezes at 32 F and 212 F. so 180 degrees between.

data

observations obtained while performing an experiment. quantitative data: numerical data obtained by various measurements on a system under city. the ice has a density of 0.9710 grams per cubic meter is quantitative. more useful bc can be compared and patterns show. qualitative data: non-numerical data consisting of general observations about a system under study. ice is less dense than liquid water.

how many digits are recorded as part of a measurement

only one estimated digit is ever recorded as part of a measurement.

percent equation

percent = (number of items of interest / total number of items) x100