1b - elements compounds and mixtures Flashcards
Explain what is meant by centrifuging
It is a method for separating out particles of different densities in a substance.
What is an atom?
An atom is the smallest particle of a chemical element that can exist.
What is an element?
An element is a substance made up of only one type of atom.
Elements can be classified into two groups based on their properties; what are these groups?
Metals and non-metals
What is a compound?
Two or more elements combined chemically in fixed proportions which can
be represented by formulae
Do compounds have the same properties as their constituent elements?
No, they have different properties.
What is a mixture?
A mixture consists of two or more elements or compounds not chemically
combined together
What are the methods through
which mixtures can be separated
(there are five)?
Filtration, evaporation/crystallisation, simple distillation, fractional
distillation and chromatography
Describe and explain simple
distillation.
Simple distillation is used to separate liquid from a solution – the liquid boils off and condenses in the condenser.
Describe and explain evaporation
Evaporation is a technique for separation of a solid dissolved in a solvent from the solvent
Describe and explain crystilisation
we remove some of the solvent by evaporation to form a saturated solution
Describe and explain fractional distillation
Fractional distillation is a technique for separation of a mixture of liquids. they have to have the same bp
Describe and explain filtration
Filtration is used to separate an insoluble solid suspended in a liquid. The insoluble solid gets caught in the filter paper, because the particles are too big to fit through the holes in the paper.
Describe and explain chromatography
Chromatography is used to separate a mixture of substances dissolved in a solvent.
How is Rf value calculated?
Distance moved by the spot / distance moved by solvent
What is a separating funnel?
A separatory funnel is an apparatus for separating immiscible liquids.
Explain the following: solute, solvent, solution, miscible, immiscible, soluble, insoluble.
-A solute is a substance that is dissolved in a solvent. Together they form a solution.
-Miscible refers to the substances that mix together in all
proportions, e.g. water and alcohol.
-Soluble refers to the substance that can be dissolved in a solvent, -An insoluble substance won’t dissolve in a particular solvent.
true or false:
compounds can be separated into their elements by physical means
false:
compounds cannot be separated into their elements by physical means
what is the difference between a compound and a mixture?
a compound consist of two or more chemically combined elements, but a mixture consists of two or more substances that aren’t chemically combined.
what is the difference between an element and a compound?
an element only consists of one of itself, as for a compound consists of two or more chemically combined elements
