1(a, b, c, d, e) Flashcards
What is sublimation and deposition?(2)
Sublimation is the conversion of a solid directly to a gas.
Deposition is the conversion of a gas directly in a solid.
Define solvent, solute, solution and saturated solution.(2)
The substance that dissolves is called the solute. The liquid it dissolves in is the solvent. The liquid formed is a solution.
A saturated solution is a solution which contains as much dissolved solid as possible at a particular temperature.
What is solubility per 100g of solvent and how can we experiment this for water?(4)
The mass of solute which must dissolve in 100g of solvent at that temperature to form a saturated a solution.
Take potassium nitrate, in water, at 40C. First we add potassium nitrate to water in a boiling tube at exactly 40C until there is an undissolved solid left over.
Pour some(doesn’t have to be all) of the solution onto an evaporating basin and weigh the entire thing. Heat the evaporating basin and contents to evaporate off all the water - heat to constant mass to check it is finished.
Finally solubility(g/100g) = mass of solute / mass of solvent x 100.
What is an element, compound and mixture?(3)
Elements are substances that can’t be split into anything simpler by chemical means - elements contain only one type of atom.
Compounds are formed when two or more elements chemically combine.
Mixtures are when various substances are mixed together and no chemical reaction occurs. Mixtures can be separated by physical means but compounds cannot.
Describe filtration?
Filtration is used to separate a solid from a liquid. The residue is the substance left in the filter paper, and the liquid comes through the filtrate.
Describe crystallisation?
Crystallisation is used to separate a solute from a solution. The solution is heated in an evaporating basin to boil off water until an almost saturated solution is formed.
Describe simple distillation?
Simple distillation is used to separate the components of a solution. It is heated in a flask and then the gas is condensed back into a liquid.
Describe fractional distillation?
Fractional distillation is used to separate a mixture of liquids such as ethanol and water. This is a very similar method to simple distillation except that there is a fractioning column present, which separates boiling points to a much finer degree.
What is chromatography how can you calculate the retardation factor?(4)
Paper chromatography can be used to separate coloured inks or food colourings. Most inks and food colourings are not just made up of one colour, but contain a mixture of dyes.
One can use paper chromatography to identify the particular dyes in a mixture.
Retardation factor = distance moved by a spot / distant moved by the solvent front
An Rf value must be between 0 and 1.
How can one investigate paper chromatography using food colourings?(4)
Draw a line with a pencil across the chromatography paper; 1 cm from the bottom.
Put a spot of the mixture of dyes on the pencil line and suspend the chromatography paper in a beaker that contains a small amount of solvent - it is important the solvent is below the pencil line.
Put a lid on the beaker, and wait. After the solvent has moved up the paper about 1 cm from the top, remove the paper and draw a pencil line to show where the solvent reached.
Let the paper dry so that the solvent evaporates. The final pattern is called a chromatogram.
What is an atom and a molecule?
A molecule consists of two or more atoms chemically bonded(by covalent bonds). The atoms in a molecule can be the same elements or different elements.
What is a group and period in the periodic table?
The horizontal rows are called periods. The vertical columns are called groups.
What are some properties of metals?(4)
Tend to be solids with high melting and boiling points.
Metallic lustre(shiny) when they are polished or freshly cut.
Ductile, malleable and good conductors.
Form positive ions in their compounds as well as only form ionic compounds.
What are some properties of non-metals?(4)
Low melting and boiling points.
Brittle as solids, no metallic lustre.
Poor conductors of heat(except diamond) and usually can’t conduct electricity.
Form both ionic and covalent compounds, usually forming negative ions in their ionic compounds.
Why do noble gases not readily react?
Noble gases are group 0 elements, and because their outermost shell has no space for more electrons they are almost completely unreactive. Helium and neon don’t react with anything.
