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AS Chemistry (Unit 1: F321) > Moles and equations > Flashcards

Flashcards in Moles and equations Deck (14)
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What is the Avogadro constant?

The number of atoms in one mole of carbon-12 atoms. The number of particles in one mole of a substance. 6.02*10^23.


What is 'amount of a substance'?

The quantity of a substance in moles. A measure for how many atoms of a substance there are in a given mass.


What is a 'mole'?

The amount of a substance with exactly the same number of particles as there are atoms of carbon-12 in exactly 12g of carbon-12.


What is the empirical formula of a substance?

The simplest whole number ratio of atoms present in a compound.


What is the molecular formula of a substance?

The actual number of atoms of different elements present in a molecule.


What is an anhydrous compound?

A pure compound that contains no water of crystallisation.


What is a hydrated compound?

A compound that contains water as part of its final structure. This is often the water of crystallisation as many ionic compounds cannot crystalise without water present.


What is water of crystallisation?

The water molecules contained in a crystalline structure when a compound crystallises in water, and become an essential part of the structure.


What is a acid?

A species which is a proton donor.


What is a base?

A species which is a proton acceptor.


What is an alkali?

A base that is soluble in water and forms OH- ions.


What is a salt?

A compound formed when the H+ ions of an acid is replaced with metal ions or ammonium ions.


What is the test for halide ions?

Add aqueous silver nitrate to the solution in question.
1. If a white precipitate is formed, chloride ions are present.
2. If a cream precipitate is formed, bromide ions are present.
3. If a yellow precipitate is formed, iodide ions are present.


What other test can be performed on the precipitates as an extra distinguishing factor?

1. Dilute ammonia solution is added to the mixture. If the precipitate dissolves, chloride ions are present as chloride ions dissolve in dilute ammonia.
2. If the the precipitate doesn't dissolve in dilute ammonia, concentrated ammonia can be added. If the precipitate dissolves, bromide ions are present; if not, iodide ions are present.