Forces, Solutions, Acids and Alkalis, and Separation Techniques

Comprehensive vocabulary flashcards covering forces, friction, drag, acids, alkalis, neutralisation, solutions, solubility, and separation methods such as distillation and chromatography.

Force

A push, pull, or twist that acts upon an object, measured in Newtons ($\text{N}$).

Friction

A contact force that acts in the opposite direction to movement when two surfaces rub together, generating heat, causing wear, and making movement more difficult.

Lubrication

A technique used to reduce friction between moving mechanical surfaces, often utilizing substances like motor oil to prevent metal parts from wearing away.

PTFE

A low-friction plastic used in modern taps for moving parts instead of rubber and brass.

Air resistance

A type of friction that occurs between air particles and another material moving through the air, opposing the object's motion.

Water resistance

A form of drag or friction experienced when an object moves through water due to collisions between the object's surface and water particles.

Streamlined

A shape designed for vehicles, helmets, and bicycles that minimizes air resistance to allow for higher speeds.

Forces diagram

A diagram where an object is represented as a box or dot with arrows pointing in the direction of each force, with arrow length proportional to force magnitude and labelled with names and values in Newtons ($\text{N}$).

Acid

A chemical substance with a pH below 7 that tastes sour, is corrosive or an irritant, and turns litmus paper red.

Alkali

A base that dissolves in water, characterized by a pH above 7, a bitter or soapy taste, a slippery feel, and the ability to turn litmus paper blue.

pH scale

A scale ranging from 0 to 14 measuring how acidic or alkaline a substance is, where 7 is neutral, values of 0 to 3 are strongly acidic, and values of 12 to 14 are strongly alkaline.

Neutralisation

A chemical reaction where an acid and an alkali react together to cancel each other out, producing a salt and water ($\text{Acid} + \text{Alkali} \rightarrow \text{Salt} + \text{Water}$).

Indicator

A chemical substance (such as litmus, universal indicator, or red cabbage) that changes colour to show whether a solution is an acid or an alkali.

Acid rain

Rain with a lower pH than normal (less than 5.6) caused by sulfur dioxide and nitrogen oxides from burning fossil fuels reacting with water vapor to form sulfuric and nitric acids.

Solution

A homogeneous mixture formed when a solute (solid, liquid, or gas) completely dissolves into a solvent.

Solute

The substance (solid, liquid, or gas) that dissolves in a solvent to form a solution.

Solvent

The liquid substance capable of dissolving a solute to form a solution.

Soluble

The property describing a substance that can dissolve in a specific solvent.

Insoluble

The property describing a substance that does not dissolve in a specific solvent.

Concentrated solution

A solution that contains a large amount of dissolved solute relative to the volume of solvent.

Dilute solution

A solution containing only a small amount of dissolved solute in the solvent.

Solubility

The maximum amount of solute that can dissolve in a specific volume of solvent at a specific temperature.

Saturated solution

A solution in which the maximum possible amount of solute has dissolved at a specific temperature, meaning no more solute can dissolve.

Supersaturated solution

A solution that contains more dissolved solute than normal saturation allows at that temperature, where no more solute dissolves and crystals may form.

Distillation

A separation technique used to separate a liquid (solvent) from a mixture and retain it by boiling the solution and condensing the vapour back into a liquid via cooling.

Chromatography

A separation method producing a chromatogram that distinguishes pure substances (one spot) from impure substances (two or more spots) and allows identification by spot colour and distance travelled.