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Flame test of a few metal ions A flame test involves introducing a sample of the element or compound to a hot, non-luminous flame and observing the color of the flame that results. [ 4 ] The compound can be made into a paste with concentrated hydrochloric acid, as metal halides , being volatile, give better results. [ 5 ]
A metal ion in aqueous solution or aqua ion is a cation, dissolved in water, of chemical formula [M(H 2 O) n] z+. The solvation number , n , determined by a variety of experimental methods is 4 for Li + and Be 2+ and 6 for most elements in periods 3 and 4 of the periodic table .
A formulae booklet was available to all candidates for all examinations up to and including those in 2018. As of 2019, candidates are no longer be issued with a formulae booklet; instead they will be expected to recall, or know how to derive quickly, standard formulae.
In 1994 the A* grade was added above the grade A to further differentiate attainment at the very highest end of the qualification. This remained the highest grade available until 2017, when numerical grades were introduced (see below). The youngest pupil to gain an A* grade was Thomas Barnes, who earned an A* in GCSE Mathematics at the age of 7 ...
The molar ionic strength, I, of a solution is a function of the concentration of all ions present in that solution. [3]= = where one half is because we are including both cations and anions, c i is the molar concentration of ion i (M, mol/L), z i is the charge number of that ion, and the sum is taken over all ions in the solution.
GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.
The practical importance of high (i.e. close to 1) transference numbers of the charge-shuttling ion (i.e. Li+ in lithium-ion batteries) is related to the fact, that in single-ion devices (such as lithium-ion batteries) electrolytes with the transfer number of the ion near 1, concentration gradients do not develop. A constant electrolyte ...
A simple qualitative method to determine the presence of phosphate ions in a sample is as follows. A small amount of the sample is acidified with concentrated nitric acid, to which a little ammonium molybdate is added. The presence of phosphate ions is indicated by the formation of a bright yellow precipitate layer of ammonium phosphomolybdate ...