chemical analysis, assessing purity and separating mixtures, flame tests Flashcards
what is the smallest particle of an element
an atom
what is a molecule
it is a particle that consists of 2 or more atoms that are chemically combined
what is an element
it is a substance that consists of only 1 type of atom that cannot be easily separated
what is a compound
It is a substance that consists of two or more elements that are chemically combined
what is a mixture
it is where 2 or more substances are mixed but not chemically combined. there are no chemical bonds between them
properties of mixtures
A mixtures components are easily separated because they are not chemically joined together
properties of compounds
the components of a compound do not retain their individual properties. both sodium and chloride are poisonous; their compound, table salt (sodium chloride) is absolutely essential to life
it takes large inputs of energy to separate the components of a compound because they are chemically combined
what is a pure substance
it is a single element or compound not mixed with any other substances
what is the melting point
it is the temperature at which a solid changes into a liquid
what is the boiling point
it is the temperature at which a solid changed into a liquid
what is a formulation
it is a mixture which has been designed as a useful product and is formed by mixing together several different substances in carefully measured quantities to ensure the product has the required properties
what is a soluble substance
it is substance is one which dissolves in water
what is a insoluble substance
it is substance is one which doesn’t dissolves in water
what is a solute
it is a soluble substance which dissolves in water
what is a solvent
it is the liquid which a solute dissolves in
what is a solutions
it is formed when a solute dissolves in a solvent
what is the residue
it is the solid which remains on the filter paper
what is filtrate
it is the solution which passes through the filter paper
what is distillate
it is the liquid which is collected by condensation of a vapor during the distillation process
what is miscible
liquid mix
what is immiscible
liquid doesn’t mix
what is evaporation
occurs when a liquid changes to a gas below the boiling point
what is condensation
occurs when a gas changes to a liquid
what is the RF mean
distance moved by spot distance moved by solvent
what is anhydrous copper (ll) sulfate
it is a white solid which doesn’t contain any water of crystallisation if added to water it will turn from white to blue and if it was heated with the water it will turn from blue back to white
explain filtration
This method works by pouring a mixture of an insoluble solid and a liquid (which could itself be a solution through filter paper in a filter funnel. The solid, called the residue, is caught in the filter paper. The liquid called the filtrate, passes through the filter paper and is collected as it drips out of the spout of the funnel.
explain evaporation and crystallisation
This method works by boiling off a liquid from a solution which contains a solid (called a solute) dissolved in a liquid (called a solvent) which is often water. This is done in an evaporating basin to leave a solid (called the residue). Better crystals can be obtained by heating the solution gently until only half of its original volume remains. The concentrated solution is then allowed to cool and crystallise. If some solution remains, then further filtration can be used to obtain the crystals of solute which then be dried between two sheets of filter paper.
explain simple distillation
This method is used to obtain a solvent from a solution. The liquid is boiled off in a flask and then its vapour is cooled by using a Liebig condenser so that it condenses back to a liquid. The collected liquid is called the distillate, Simple distillation can also be used to separate two miscible liquids whose boiling points are far apart.
explain fractional distillation
This method works by separating a mixture of two or more miscible liquids whose boiling points are quite close together. It is similar to simple distillation except that a special tube called a fractionating column is placed between the flask and the condenser. As the liquid is heated, the liquid with the lowest boiling point boils off first. This is then condensed and collected as a pure liquid. After the first liquid has been collected the second liquid may be distilled over and so on. The different distillates are known as fractions.
explain separating funnel
If two Liquids do not mix, they are said to be immiscible eg oil and water. The separation of two immiscible liquids is very simple. The mixture is placed in a separating funnel where the less dense liquid will form the upper layer. The two liquids can then be run out of the funnel one after the other.
explain chromatography
Paper chromatography is the simplest type of chromatography. It works by separating a mixture of different soluble substances (usually with different colours). A spot of the mixture is placed on some chromatography paper (stationary phase) which is then dipped into a solvent (mobile phase). As the solvent passes up the paper, the mixture separates aut as different spots as each substance in the mixture moves at a different rate up the paper. The components separate because some are more attracted to the paper whilst others are more attracted to the solvent. Those that prefer to dissolve in the solvent move faster and travel further up the paper.
what colour flame is Potassium K+
lilac
what colour flame is Calcium Ca2+
brick red
what colour flame is Copper(ll) Cu2+
blue-green
what colour flame is Sodium Na+
pick one between yellow or orange
what colour flame is Lithium Li+
crimson
