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Chemistry (CP)

Módulo 1 · Texto Lab Safety
Módulo 2 · Texto The Scientific Method
Módulo 3 · Mídia Law Vs. Theory
Módulo 4 · Mídia Accuracy Vs. Precision
Módulo 5 · Texto Sig-Figs and Scientific Notation Você está aqui
Módulo 6 · Texto Matter
Módulo 7 · Texto Displacement
Módulo 8 · Texto Density
Módulo 9 · Texto SI Units
Módulo 10 · Mídia Dimensional Analysis
Módulo 11 · Mídia The Periodic Table
Módulo 12 · Texto Isotopes
Módulo 13 · Texto Nuclear Reactions
Módulo 14 · Texto Nuclear Fission and Fusion
Módulo 15 · Texto Chemical Vs. Nuclear Reaction
Módulo 16 · Texto Electron Shells
Módulo 17 · Texto Ions
Módulo 18 · Texto Solubility and Conductivity
Módulo 19 · Mídia Types of Bonding
Módulo 20 · Texto Chemical Formulas
Módulo 21 · Texto Functional Groups
Módulo 22 · Texto Electron Domains
Módulo 23 · Texto Polarity
Módulo 24 · Texto Chemical Equations
Módulo 25 · Texto Physical Vs. Chemical Change
Módulo 26 · Texto Types of Reactions
Módulo 27 · Texto Moles
Módulo 28 · Texto Solubility and Molarity
Módulo 29 · Mídia Miracle Moles
Módulo 30 · Texto Acids and Bases
Módulo 31 · Mídia pH and pOH
Módulo 32 · Texto Dilutions
Módulo 33 · Texto Neutralization Reactions and Titrations
Módulo 34 · Texto Mol Ratios
Módulo 35 · Mídia Stoichiometry
Módulo 36 · Texto Endothermic and Exothermic Energy Transfer
Módulo 37 · Texto Specific Heat
Módulo 38 · Mídia Heating and Cooling Curves and Phase Change
Módulo 39 · Texto Gas Laws and Kinetic Molecular Frequency.

Módulo 5 de 39 · Texto

Sig-Figs and Scientific Notation

Enyx Jiang

Significant Figures

The significant figures in a measurement include all the digits that can be known precisely plus a last digit that must be estimated

Rules:

Every non-zero digit in a recorded measurement is significant
Zero Rules:
- Leading Zeros- zeros that precede all the non-zero digits; NEVER count as sig-figs
  - eg. 0.00832-- 3 sig-figs
  - eg. 0.23-- 2 sig-figs
- Captive Zeros- zeros between non-zero digits; are counted as sig-figs
  - eg. 7003-- 4 sig-figs
  - eg. 409.076-- 6 sig-figs
- Trailing Zeros- zeros at the right end of a number; only count as sig-figs when there is a decimal point
  - eg. 456200-- 4 sig-figs
  - eg. 50938.00-- 7 sig-figs
Exact Numbers
- Obtained by counting, not by measuring devices
- Can be assumed to have an unlimited amount of sig-figs
- Can come from definitions
  - eg. 1 in.=2.54 cm
Multiplying and Dividing sig-figs
- The answer must contain no more sig-figs than the measurement with the least sig=figs
- The position of the decimal point is irrelevant
  - eg. 5.89 x 4.5 = 27
Adding and Subtracting sig-figs
- The answer must contain the same number of sig-figs to the right of the decimal point as the measurement with the fewest sig-figs to the right of the decimal point
  - eg. 61.2 = 9.621 = 70.2

Scientific Notation

Chemists use scientific notation is used for very large or small numbers

eg. the mass of a hydrogen atom is 0.00000000000000000000000167 grams
eg. 2.0 grams of hydrogen is composed of 602000000000000000000000 hydrogen molecules

Numbers are written as the product of two numbers:

A coefficient
A power of 10 with an exponent
- The exponent tells you how many times you multiply a number by 10
- Numbers greater than 1 have a positive exponent (# of places the decimal moves left)
- Numbers less than 1 have a negative exponent (# of places the decimal moves right)
  - eg. The number 23000 is written in exponential form as 2.3 x 10^4
  - eg. 0.000051 is written in exponential form as 5.1 x 10^-5
- Numbers between 1 and 10 do not need scientific notation
  - eg. 9 = 9 x 10⁰
  - 1.2 = 1.2 x 10⁰
  - 7.562580 = 7.562580 x 10⁰
    - All have an exponent of zero (10⁰ = 1)