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17 Cards in this Set
- Front
- Back
what is the relative charge of a neutron? what is its relative mass? |
- a neutron’s relative charge is 0 - relative mass of a neutron is 1 |
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explain what is meant by the term isotopes |
isotopes are different forms of the same element, which have the same number of protons but different numbers of neutrons |
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why do atoms have no charge? |
atoms have the same number of protons and electrons and neutrons are neutral |
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what is a compound |
a compound is a substance formed from two or more different elements in fixed proportions, held together by chemical bonds |
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what type of process is needed to separate a compound into its elements why should |
you need a chemical reaction |
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why should you put a lid on the container during a paper chromatography experiment |
a lid helps to stop the solvent from evaporating |
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what is a solvent from |
the point that the solvent in paper chromatography reaches as it moves up the paper |
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what is a mixtureexplain |
a mixture consists of two or more elements or compounds that are combined, but not chemically bonded together |
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explain why techniques to separate mixtures are described as physical processes when |
the separation of a mixture is a physical process because it does not involve any chemical reactions and no new substances are made |
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when can filtration be used to separate a mixture |
filtration can be used when you have a mixture of an insoluble solid and liquid |
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when is crystallisation used to separate a mixture |
crystallisation is used to separate a soluble solid from a solution |
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explain how filtration works |
- filtration works by passing the mixture through a filter - the liquid passes straight through, but the insoluble solid particles are caught by the filter |
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why might crystallisation be used instead of evaporation |
crystallisation is used if the salt will decompose when heated, or if you want to make big crystals of the salt |
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what equipment would you need to carry out a crystallisation |
- evaporating dish - heat source - beaker - flask - funnel - filter paper |
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in fractional distillation where is the hottest point of the fractioning column |
the bottom of the fractioning column |
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mixtures of liquids, including those with similar boiling points a |
mixtures of liquids, including those with similar boiling pointsa |
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explain why simple distillation can’t be used to separate substances with similar boiling point |
if the boiling points of the compounds are too close together, they will all evaporate and mix together again |