Physical properties

Mass and weight, though often used loosely as synonyms in everyday speech, are physically distinct: mass is an inherent property of matter, the measure of how much matter a body actually contains, and it does not change with the body's position; weight, on the other hand, is the result of that mass being acted on by gravity, so a body's weight varies depending on how strong the local gravitational pull is (which itself varies with distance from the centre of the earth) — mass is therefore the more fundamental of the two properties. The SI base unit of mass is the kilogram, though the smaller unit 'gram' (1 kg = 1000 g = 10^3 g) is far more convenient for weighing out the small quantities of chemicals typically used in a laboratory. Length comes up in chemistry when discussing very small quantities such as atomic radius, bond length, or the wavelength of electromagnetic radiation, which is why fractional SI length units like the nanometre (1 nm = 10^-9 m) and picometre (1 pm = 10^-12 m) are used instead of the metre itself. Volume is the amount of three-dimensional space a body occupies, independent of its shape; the commonly used unit litre (L) is not itself an SI unit, but is related to the SI unit as 1 L = 1 dm3 = 1000 mL = 1000 cm3, while the true SI unit of volume is the cubic metre (m3). Laboratory glassware such as the graduated cylinder, burette, pipette and volumetric flask are the standard tools used to measure the volume of liquids and solutions with differing degrees of precision. Density is a substance's mass per unit volume, calculated by dividing a measured mass by the corresponding measured volume, and — being independent of how much of the substance is present — it is a characteristic property of that substance; its SI unit works out to kg/m3 (or kg m-3), while the CGS-based unit commonly used in the laboratory is g/mL (equivalently g mL-1 or g cm-3). Temperature is a measure of how hot or cold something is, and three scales are in common use: degree Celsius (°C), degree Fahrenheit (°F), and Kelvin (K) — the last of which is the true SI unit. On …