# Basics

## The SI-system, unit converters, physical constants, drawing scales and more

### Acceleration of Gravity and Newton's Second Law

Acceleration of gravity and Newton's Second Law - SI and Imperial units.

### Acceleration Units Converter

Converting between units of acceleration.

### Air - Thermophysical Properties

Thermal properties of air at different temperatures - density, viscosity, critical temperature and pressure, triple point, enthalpi and entropi, thermal conductivity and diffusivity and more.

### Angle Converter

Converting between angle units.

### Area Units Converter

Convert between units of area.

### British Imperial System

A principal system of units.

### Buffer Solutions

Definitions, explanations and examples of how to make buffer solutions.

### Circles - Circumferences and Areas

Circumferences and areas of circles with diameters in inches.

### Concentration Units Converter

Calculator and formulas for conversion between different units of concentration: Molarity, molality, mole fraction, weight percent of solute and grams of solute per liter of solution - descriptive terms for solubility.

### Convert between Gallons and Pounds of Water

- and vice versa.

### Decimal System Prefixes

Prefix names used for multiples and submultiples units.

### Density vs. Specific Weight vs. Specific Gravity

An introduction to density, specific weight and specific gravity.

### Dimensionless Numbers

Physical and chemical dimensionless quantities - Reynolds number, Euler, Nusselt, and Prandtl number - and many more.

### Drawing Scales

Commonly used blueprint drawing scales.

### Efficiency

The measure of usefulness.

### Electromagnetic Spectrum

The electromagnetic spectrum with wavelengths and frequencies.

### Elements of the Periodic System

The elements of the periodic system with names, symbols, atomic numbers and weights, melting and boiling points, density, electronegativity and electron affinity, and electron configuration.

### Empirical Equations

Equations based on observations and experience.

### Equilibrium

The mechanical, thermal, electrostatic, phase or chemical states of equilibrium.

### Exponents - Powers and Roots

The laws of fractional and integer exponents.

### Fractions and Decimal Inches Equivalents

The inches fractional and decimal equivalents.

### Fuel Equivalents - Online Calculator

Online fuels energy equivalents calculator for oil, gas and more.

### Geological Time

Geological periods and time scale.

### Heat Capacity

The amount of heat required to change the temperature of a substance by one degree.

### Humid Air vs. the Ideal Gas Law

Pressure, temperature and volume in a perfect ideal gas like moist air (air with water vapor).

### Inches - Fractional vs. Decimal Equivalents

The decimal equivalents of eights, sixteenths, thirty-seconds and sixty-fourths of an inch.

### Inches vs. Feet, Yards and Meters - Conversion Chart

Convert between inches, feet, yards and meters.

### Inches vs. mm - Conversion Chart

Convert fractional and/or decimal inches to metric mm - and vice versa.

### Length - Online Unit Converter

Convert between length units like meters, feet, inches, nautical miles and more.

### Logarithms

The rules of logarithms - log_{10} and log_{e} for numbers ranging 1 to 1000.

### Mass Moment of Inertia

The Mass Moment of Inertia vs. mass of object, it's shape and relative point of rotation - the Radius of Gyration.

### Mass vs. Weight

Mass vs. weight - the Gravity Force.

### Mixtures, Solutions and Suspensions

Mixtures vs. solutions vs. suspensions.

### Mole and the Avagadro's Number

The mole is the SI base unit for an amount of a substance.

### Naming Inorganic Binary Compounds

Rules for naming inorganic ionic and covalent types of chemical compounds.

### Naming of Organic Compounds

Nomenclature rules for different groups of organic compounds and functional groups, together with examples of use of the rules.

### Non-ideal gas - Van der Waal's Equation and Constants

The van der Waals constants for more than 200 gases used to correct for non-ideal behavior of gases caused by intermolecular forces and the volume occupied by the gas particles.

### Optical Distance Law

Geometric dilution of light vs. distance.

### Ounces and Pounds vs. Grams

Converting ounces (*ozs.*) and pounds (*lbs.*) to grams (*g*).

### Parts per Million - ppm

ppm - or parts per million - is commonly used as a unit of concentration.

### Periodic Table of Elements

The periodic table of the elements with their atomic numbers.

### pH - Basic (alkaline) vs. Acidic

Introduction to pH - the acidic and basic (alkaline) definition.

### Physical Constants

Physical constants - SI Units.

### Pressure

Introduction to pressure - online pressure units converter.

### Pressure Units - Online Converter

Convert between pressure units like *Pa, bar, atmosphere, pound square feet, psi* and more.

### Pressure vs. Head Unit Converter

Pressure vs. head units - like *lb/in ^{2}, atm, inches mercury, bars, Pa *and more.

### Property vs. State

The concept of properties and state.

### Pumps, Fans and Turbines - Horsepower

British Horse Power as used for pumps, fans and turbines - and how to convert to other units.

### Radians vs. Degrees

Radian is the SI unit of angle. Convert between degrees and radians. Calculate angular velocity.

### Radiation Units - Becquerel to Curie

Converting between Bequerel and Curie radiation units.

### Ratios and Proportions

The relative values between quantities - ratios and proportions.

### Real Numbers Algebra

The commutative and associative law for addition and more.

### SI System

An introduction to the SI metric system.

### Solar System Constants

Properties and data for the Sun, the Earth and the Moon.

### Solids - Volumes and Surfaces

The volume and surface of solids like rectangular prism, cylinders, pyramids, cones and spheres - online calculator.

### Solubility

The amount of a solute that can be dissolved in a solvent.

### Solutions, Molarity and Dilution

Definitions and examples of how to calculate wt%, molarity and how to prepare dilutions.

### Some Measuring Units

Commonly used measuring units - like gross, dozen, quire, sheets and more.

### Specific Heat - Online Unit Converter

Online specific heat converter with the most commonly used units.

### Standard State and Enthalpy of Formation, Gibbs Free Energy of Formation, Entropy and Heat Capacity

Definition and explanation of the terms standard state and standard enthalpy of formation, with listing of values for standard enthalpy and Gibbs free energy of formation, as well as standard entropy and molar heat capacity, of 370 inorganic compounds.

### STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure

The definition of STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure.

### Symbols Used to Denote a Chemical Reactions and Process or Condition

Explanation of symbols used as subscripts or superscripts to tell more about the type of chemical reaction, process or condition.

### Temperature

Introduction to temperature - including Celsius, Fahrenheit, Kelvin and Rankine definitions - and an online temperature converter.

### The Ideal Gas Law

The relationship between volume, pressure, temperature and quantity of a gas, including definition of gas density.

### Thermodynamics Key Values Internationally Agreed

Internationally agreed, internally consistent, values for the thermodynamic properties (standard enthalpy of formation, entropy and [H°(298)-H°(0)]) of key chemical substances.

### Total and Partial Pressure - Dalton's Law of Partial Pressures

How to calculate total pressure and partial pressures for gas mixtures from Ideal Gas Law.

### Trigonometric Functions

Sine, cosine and tangent - the natural trigonometric functions.

### Unit Converter with commonly used Units

Common converting units for Acceleration, Area, Density, Energy, Energy per unit mass, Force, Heat flow rate, Heat flux, Heat generation per unit volume and many more.

### USCS - United States Customary System Units

An overview of the United States Customary System Units - Imperial Units.

### Vector Addition

Online vector calculator - add vectors with different magnitude and direction - like forces, velocities and more.

### Velocity Units - Online Converter

Convert between common velocity and speed units.

### Volume Converting Chart - Gallons vs. Cubic Feet vs. Cubic Meters and more.

Convert between volume units like U.S. liquid gallons, U.K. liquid gallons, cubic feet, cubic metre and more.

### Volume Flow - Online Unit Converter

Convert between volume flow units like *gpm, liter/sec, cfm, m ^{3}/h*.

### Volume Units Converter

Convert between common volume units like cubic metre, cubic feet, cubic inches and more.

### Water Content in Food and other Products

Water content before and after drying - in food and other products cork, grain, soap, peat, wood and more.

### Water Pressure vs. Head

Pressure in *pounds per square inch (psi)* vs. head in *feet of water (ft _{h2o})*.