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Intro to Chemistry
Intro to Chemistry
25
Chemistry
Undergraduate 3
09/05/2012

Additional Chemistry Flashcards

 


 

Cards

Term

 

Chemistry

Definition

 

the science that deals with the materials of the universe and the changes that these materials undergo;

the study of matter

Term

 

Scientific method

Definition

 

Observation:  qualitative or quantitative (measurement involving a number)

Hypothesis:  a possible explanation for the observation

Experiment:  testing the hypothesis

Theory - - - Law

A law tells what happened; a theory (model) is our attempt to explain why it happens

 

Theory:  a set of tested hypotheses that gives an overall explanation of some part of nature; an interpretation

 

Law: a summary of observed (measurable) behavior

Term

 

Steps used to solve problems

 

Definition

1.  recognize the problem and state it clearly

making an observation

 

Term

 

Theory

Definition

 

a set of tested hypotheses that gives an overall explanation of some part of nature

 

an observation is something that is witnessed and can be recorded.  A theory is an interpretation - a possible explanatino of why nature behaves in a particular way

Term

Law

 

Theory

Definition

A law is a summary of observed behavior; whereas a theory is an explanation of behavior.

 

A law tells what happened; a theory (model) is our attempt to explain why it happened

Term

measurement =

 

quantitive observation

Definition
must always consist of a number and a unit
Term
Scientific notation
Definition

simply expresses a number as a product of a number between 1 and 10 and the appropriate power of 10. 

 

93,000,000 = 9.3 x 10^7

 

the number of places the decimal point is moved determines the power of 10; the direction of the move determines whether the power of 10 is positive (left) or negative 9 (right)

Term
Unit
Definition
part of a measurement that tells what scale or standard is being used to represent the results of the measurement
Term
fundamental SI units
Definition

mass          kilogram           kg

length          meter          m

time          second          s

temperature          kelvin          k

Term
fundamental SI unit of length
Definition

1 m = 39.37 in

 

1 in = 2.54 cm

Term

 

volume - m

 

 

mass - kg

Definition

the amount of three dimensional space occupied by a substance

 

 

the quantity of matter present in a object

 

1 L = 1000 mL

 

1 kg = 1000 g

0.001g = 1 mg

 

 

 

Term

Every measurement has some degree of uncertainty

 

The numbers recorded ina measurement (all the certain numbers plus the first uncertain number) are called significant figures

 

 

Definition
Term
rules for counting significant figures
Definition

Non zero integers ALWAYS count as significant figures

 

Leading zeros are are zeros that precede all of the nonzero digits.  They NEVER count as significant; they simply indicate the position of the decimal point.

 

Captive zeros are zeros that fall between nonzero digits.  They  ALWAYS count as significant figures. 

 

Trailing zeros are  zeros at the right end of the number;  They are only significant if the number is written with a decimal point.

 

Exact numbers NEVER LIMIT the number of significant figures in a calculation.

Term
rules for using significant figures in calculations
Definition

For multiplication and division, the number of significant figures in the result is the same as that in the measurement with the smallest number of significant figures.  LIMITING

 

For addition and subtraction, the limiting term is the one with the smalles number of decimal places.

Term

Conversion factor

 

Equivalance statement

 

dimensional analysis

Definition

a ratio of the two parts of the statement that relates to two units

 

 

1 in = 2.54 cm

the respective numbers are different because they refer to different scales

 

Changing from one unit to another via conversion factors (based on the equivalance statements between the units)

Term

 

Temperature

Definition

Freezing and boiling points

(the difference is 100 on both scales)

 

 

Fahrenheit     32     212

Celsius            0     100

Kelvin           273    373

 

TK = TC + 273 

TC = TK - 273

 

TF = 1.80 (TC) + 32

TC = TF - 32 / 1.80    

 

Term
Density
Definition

the amount of matter present in a given volume of substance

 

D = mass / volume  in g/mL or g/cm^3

 

 the device used to test the density of a solution is a hydrometer

Term
Specific gravity
Definition

the density of a liquid;

the ratio of a given liquid to the density of H2O at 4C

Term

Matter

 

 

Definition

the stuff of which the universe is composed; has two characteristics:  it has mass and occupies space

 

States of matter:

SOLID - has fixed shape and volume

LIQUID - has definit volume but takes shape of its container

GAS - has no fixed volume or shape

 

Term

physical properties

 

chemical properties

Definition

odor, color, volume, state (solid, liquid, gas), density, melting point, and boiling point

 

its ability to form new substances

Term
Electrolysis
Definition
the decomposition of water by an electric current, a chemical proces
Term

physical change

 

chemical change

Definition

involves a change in one or more physical properties, but no change in the fundamental components that make up the substance.  The most common physical changes are changes of state.

 

involves a change in the fundamental components of the substance; a given substance changes into a different substance or substances.  Chemical changes are called reactions:  silver tarnishes

Term

Elements

 

Compounds

 

Mixture

 

Pure substance

Definition

a substance that cannot be broken down into other substances by chemical methods

 

a substance composed of a given combination of elements that can be broken down into those elements by chemical methods.  A compound always has the same composition. 

 

something that has variable composition; can be separated into pure substances: elements and/or compounds 

 

will always have the same composition; either elements or compounds

Term

homogeneous mixture / solution

 

heterogeneous mixture

Definition

is the same throughout

 

contains regions that have different properties from those of other regions

Term

distillation

 

filtration

Definition

the separation process; physical method with no chemical change

 

 

separates a liquid from a solid; physical method

 

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