Concentration

In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. The term concentration can be applied to any kind of chemical mixture, but most frequently it refers to solutes and solvents in solutions. The molar (amount) concentration has variants such as normal concentration and osmotic concentration.

Qualitative description

Often in informal, non-technical language, concentration is described in a qualitative way, through the use of adjectives such as "dilute" for solutions of relatively low concentration and "concentrated" for solutions of relatively high concentration. To concentrate a solution, one must add more solute (for example, alcohol), or reduce the amount of solvent (for example, water). By contrast, to dilute a solution, one must add more solvent, or reduce the amount of solute. Unless two substances are fully miscible there exists a concentration at which no further solute will dissolve in a solution. At this point, the solution is said to be saturated. If additional solute is added to a saturated solution, it will not dissolve, except in certain circumstances, when supersaturation may occur. Instead, phase separation will occur, leading to coexisting phases, either completely separated or mixed as a suspension. The point of saturation depends on many variables such as ambient temperature and the precise chemical nature of the solvent and solute.

Concentration (game)

Concentration, also known as Match Match, Memory, Pelmanism, Shinkei-suijaku, Pexeso or simply Pairs, is a card game in which all of the cards are laid face down on a surface and two cards are flipped face up over each turn. The object of the game is to turn over pairs of matching cards. Concentration can be played with any number of players or as solitaire. It is a particularly good game for young children, though adults may find it challenging and stimulating as well. The scheme is often used in quiz shows and can be employed as an educational game.

Rules

Any deck of playing cards may be used, although there are special cards available, as shown in the picture above. The rules given here are for a standard deck of 52 cards, which are normally laid face down in four rows of 13 cards each. The two jokers may be included for a total of six rows of nine cards each.

Additional packs can be used for added interest. Standard rules need not be followed: the cards can be spread out anywhere, such as all around the room on a freshly-vacuumed carpet, again for added interest.

Samadhi

Samādhi (Sanskrit: समाधि, Hindi pronunciation: [səˈmaːd̪ʱi]), also called samāpatti, in Hinduism, Buddhism, Jainism, Sikhism and yogic schools refers to a state of meditative consciousness. It is a meditative absorption or trance, attained by the practice of dhyāna. In samādhi the mind becomes still. It is a state of being totally aware of the present moment; a one-pointedness of mind. When someone dies in India, it is not uncommon to say, that person has gone to 'Samādhi'. The tombstone area is also referred to as a place of 'samādhi'.

In Buddhism, it is the last of the eight elements of the Noble Eightfold Path. In the Ashtanga Yoga tradition, it is the eighth and final limb identified in the Yoga Sūtras of Patañjali.

Definitions