C5 - Chemical analysis Flashcards
what is pure substance?
a substance is something that only contains one compound or element throughout
what are mixtures?
substances that contain more than one element or compound which isn’t chemically bonded
what are formulations?
what is filtration?
to separate an insoluble solid from a liquid
what is crystalisation?
separates a soluble solid from a solution
what is simple distillation?
is used for separating out a liquid from a solution, or to separate liquids that have very different boiling points
how do you calculate the relative atomic mass?
sum of (isotope abundance x isotope mass number) / sum of abundances of all isotopes
how do you calculate the percentage of mass of an element in a compound?
(atomic mass x amount of element ÷ atomic mass total of compound) x 100%
what are the 2 reasons why mass could change?
- if the mass increases, because some of the atoms in gaseous reactants end up in solid, liquid, or aqueous products
- if the mass decreases, because some of the solid/liquid/gas or aqueous reactants end up in gaseous products
what is the equation to work out the number of moles?
Number of moles = mass grams / relative formula mass
what is Avogadro’s constant?
6.0 x 10 to the power of 23
what is an acid?
is a substance that dissolves in water to release H+ ions
what is an alkali?
is a substance that produces hydroxide (OH-) ions when it dissolves in water
acid + alkali →
acid + alkali → salt + water
does the salt from the reaction contain the negative or positive ion?
negative
does the acid from the reaction contain the negative or positive ion?
positive
HCI + NaOH →
HCI + NaOH → NaCl + H₂O
what is concentration?
the amount of substance in a given volume of solution is called its concentration
how do you calculate the concentration of a solution?
g/dm concentration = mass of solute (g) / volume of solvent in dm3
how do u calculate the concentration for it to be in mols?
concentration (mol/dm) = number of moles solute (mol) / volume of solvent (dm)
