Chemistry and Measurement Definitions and Formulas Flashcards

1
Q

What is Chemistry?

A
  • The study of composition, properties, structure and transformations of matter.
  • Knowing how changes take place, allows chemist to:
    • Make more substances
    • Use clues to find new processes and create new products.
    • Inhibit certain changes to preserve useful products.
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2
Q

Experiment

A

Observation of natural phenomena carried out in a controlled manner so that the results can be duplicated and rational conclusions obtain.

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3
Q

Law

A

Concise statement or mathematical equation about a fundamental relationship or regularity of nature.

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4
Q

Hypothesis

A

A tentative explanation of some regularity of nature.

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5
Q

Theory

A

tested explanation of basic natural phenomena.

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6
Q

Mass

A

The quantity of matter in a material

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7
Q

Matter

A

general term for the material things around us, defined as whatever occupies space and can be perceived by our senses.

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8
Q

Law of conservation of mass

A

The total mass remains constant during a chemical change (chemical reaction)

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9
Q

Who is Antonine Lavoisier?

A
  • Wrote the Traite Elementaire de Chemie (Basic treaties on chemistry)
  • Father of Modern Chemistry
  • Used the Metric system
  • Insisted on using balances in chemical research
  • had explained combustion.
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10
Q

Scientific Method

A
  • Framing of laws, hypothisis or theories and the conducting of more experiments.
  • Therefore scientific knowledge is testable, reproducible, explanatory, predictive and tentative.
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11
Q

Weight

A

The force of gravity exerted on a substance or gravitational attraction of earth on the body.

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12
Q

Physical States

A
  • Given kind of matter exists in different physical forms under different conditions
    • Solid:
      • incompressible, fixed shape and volume
    • Liquid
      • Fixed volume, no fixed shape, incompressible
    • Gas
      • Takes shape and size of container, easily compresible fluid.
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13
Q

Physical Change

A

A change in the form of matter but not in its chemical identity.

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14
Q

Chemical Constitution

A

Element, compound or mixture

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15
Q

Properties

A

Characteristics used to describe or identify matter.

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16
Q

Chemical change (Chemical reaction)

A

A change in which one or more kinds of matter are transformed into a new kind of matte or several new kinds of matter.

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17
Q

Physical Property

A

Characteristic that can be observed for a material without changing its chemical identity.

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18
Q

Chemical property

A

Characteristic of a material involving its chemical change.

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19
Q

Extensive Property

A

Values that depend upon the sample size.

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20
Q

Intensive Property

A

Values that do not depend on amount of the sample

E.g. temperature and melting point of water.

21
Q

Substances

A

Kind of matter that cannot be seperated into other kinds of matter by any physical process.

22
Q

Element

A

Substance that cannot be decomposed by any chemical reaction into simpler substances.

23
Q

Compound

A

Substance composed of two or more elements chemically combined.

24
Q

Law of definite proportions

A
  • also known as the law of constant compostion
  • a pure compound, whatever its source, always contains definite or constant proportions of the elements by mass.
25
Q

Mixtures

A

A material that can be seperated by physical means into two or more substances. Classified into homogeneous and heterogeneous.

26
Q

Homogeneous Mixtures

A
  • also known as a solution.
  • uniform in its properties throughout given samples.
27
Q

Heterogeneous Mixture

A

Physically distinct parts, each with different properties.

28
Q

Phase Mixture

A

one of several different homogenous materilas present in the portion of matter under study.

29
Q

Measurement

A

Comparison of a physical quantity to be measured with a unit of measurement - a fixed standard of measurement.

30
Q

Purpose of measurement

A
  • To be able to reproduce an experiment
  • To make sure that the correct concentration or amount is used.
31
Q

Precision

A
  • Refers to the closeness of the set of values obtained from obtained from identical measurements of a quantity.
  • Or, or how well a number of independent measurements agree with one another.
32
Q

Accuracy

A
  • the closeness of a single measurement to its true value.
  • or, how close the true value a given measurement is.
  • For maximum reliability, the number obtained for measure chould contain all the digits that are known, plus one digit that is estimated. This last digit introduces some uncertainty.
33
Q

Significant Figures

A
  • Those digits in a measured number (or in the result of a calculation with measured numbers) that include all certain digits plus a final digit having some uncertainty.
34
Q

Number of Significant figures

A
  • Refers to the number of digits reported for the value of a measured or calculated quantity, indicating the precision of the value.
  • The more significant the figure, the more precise the measurement.
35
Q

What are the rules for Significant Figures?

A
  1. Zeros in the middle of a number are like any other digit; they are always significant.
    • 4.803 cm has four significant digits
  2. Zeros at the beginning of a number are not significant; they act to locate the decimal point
    • 0.00661 g has three significant digits
  3. Zeros at the end of a number and before the decimal point may or may not be significant.
    • 900 cm may be one, two or three significant figures
    • if 900. cm then there is three significant digits.
36
Q

Scientific Notation

A

The representation of a number in the form A x 10 n ,

where

  • ‘A’ is a number with a single non-zero digit to the left of the decimal point
  • ‘n’ is an integer, or whole number
37
Q

Exact Numbers

A
  • Number that arises when you count items or sometimes when you define a unit.
  • They have no effect on the number of significant figures in a calculation.
38
Q

Significant Figures in Multiplication and Division

A
  1. Give as many significant figures in the answer as there are in the measurement with the least number of significant figures.
  2. e.g. 190.6 x 2.3 = 438.38 => 440
39
Q

Significant Figures in Addition and Subtractions

A
  1. Give the same number of decimal places as the value with the fewest decimal places.
  2. 125.17 + 129 + 52.2 = 306
40
Q

Rounding

A
  • The procedure of dropping nonsignificant digits in a calculation result and adjusting the last digit reported
    • If the digit is 5 or greater, add 1 to the last digit and drop all digits to the right.
    • If the digits is 5 or less. simply drop it and all digits to the right.
41
Q

What are SI units?

A
  • 1790, the French Academy of Sciences devised the metric system.
  • International System of units or SI after the French le Système International d’Unités, which is a modernized version of the metric system established in France was adopted in 1960 by the General Conference of Weights and Measures.
42
Q

What are the seven base units of SI?

A
  1. Mass, kilogram, kg
  2. Length, meter, m
  3. temperature, kelvin, K
  4. Amount of substance, mole, mol
  5. Time, second, s
  6. Electric current, ampere, A
  7. Luminous intensity, candela, cd
43
Q

Formula to convert Celsius to Kelvin?

A
44
Q

Formula to convert Celsius to Fehrenheit?

A
45
Q

Formula to convert Fehrenheit to Celsius?

A
46
Q

Derived Units

A

Units expressed by using one or more of the seven base units

  1. Area, length squared,m2
  2. Volume, length cubed, m3
  3. Density, mass per unit volume, kg/m3
  4. Speed, distance traveled per unit time, m/s
  5. Acceleration, speed changed per unit time, m/s2
  6. Force, Mass times acceleration, kg • m/s2, also known as a Newton
  7. Pressure, force per unit area, kg/(ms2), also known as a Pascal
  8. Energy, force times distance traveled, kg • m2/s2 , also known as a Joule
47
Q

Density

A

Is the mass of an object divided by the volume: d =m/V

g/cm3 for a solid

g/mL for a liquid

Density of a substance

  • Can be used to identify the substance
  • Is temperature dependent because volume changes with temperature. Specify the temperature at which the density was measured.
48
Q

What is dimensional analysis?

A
  • Also known as: factor-label method.
  • Method of calculation in which one carries along the units of the quantities
  • We can use known relationships among the units or factors to fin the unknown quantity.
  • All conversion factors are numerically equal to 1.

(Original Qty) x (Conversion factor) = (Equivalent Qty)

49
Q

What are the steps for using dimensional analysis?

A
  1. Find out the unit given
  2. Find out the unit required in the answer
  3. Find a relationship between the given units and the required answer units.
  4. Solve the problem.