Elements from the Sea

Talentless Academic
Flashcards by Talentless Academic, updated more than 1 year ago
Talentless Academic
Created by Talentless Academic about 7 years ago
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AS Level Chemistry Flashcards on Elements from the Sea, created by Talentless Academic on 02/08/2014.

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Question Answer
How are Titrations carried out? And what do they do? Titrations allow you to find out exactly how much acid is needed to neutralize a quantity of alkali. Step1- you measure out some alkali using a pipette and put it in a flask along with some indicator eg. phenolphthalein step2- do a rough titration to get an idea where the end point is.add the acid to the alkali using a burette giving the flask a regular swirl. then an accurate titration run acid down within 2cm cubed of the end point then add acid dropwise. if youre not precise you can overshoot it. record results are repeat.
What do indicator's do? and give me an example of two and what colour they are and what they change. Indicators show you when the reactions finshed. 2 Main indicators Methyl orange- turns yellow to red when adding acid to alkali Phenolphthalein turns red to colourless when adding acid to alkali. Universal indicator isn't good because its colour change is to gradual.
What's the exception with Cr and Cu They donate one of their 4s sub shell electrons to their 3d subshell because they prefer a more stable full or half full 3d Subshell.
How does electronic structure decide the chemical properties of an element? The S block elements have 1 or 2 outer shell electrons they are easily lost to form positive ions with an inert gas configeration. Elements of group 5 and 6&7 can gain 1 2 or 3 electrons inorder to from negative ions with an inert gas configuration. groups 4&7 can also share electrons to form covalent bonds. group 0 dont need to lose or gain they have full outershells make them inert. D block lose S and D electrons to make them postive ions.
What is a Oxidising agent and reducing agent? An Oxidising agent accepts electrons and gets reduced. a Reducing agents donates electrons and becomes reduced.
What is a dipole? caused by a difference in electronegativities between two atoms .A dipole is a difference in charge between two atoms caused by a shift in electron denisty. greater difference in electronegativity the more polar a bond is.
How is a Temporary dipole produced? Van Der Waals forces cause all molecules to be attracted to each other. 1) electrons in charge clouds are constantly moving really quickly. At any particular moment the electrons in an atom are likely to be on one side than the other. At this moment this causes a temporary dipole. this diple than causes another dipole in the oppisite direction on a neighbouring atom. the two dipoles are then attracted to each other. The second dipole causes another dipole in the 3rd atom. since electrons are constantly moving temporary dipole are constantly being created and destroyed. even though they keep changing the overall effect is that the atoms to be attracted to each other.
What decides the strength of intermolecular forces. The shape eg alkanes have covalent bonds inside the molecules between the molecules there are Van Der waal forces which hold them together. The longer the carbon chain the stronger the Van Der Waal forces because there is more molecular surface area for electron interaction so as molecules get bigger it takes more energy to overcome the Van der waal forces. also branched alkanes cant pack closely together so they have less molecular surface area. so the forces are reduced.
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