Edexcel Chemistry Unit 4 &5 Watch

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#21
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#21
Its actually Cr(OH)3, coz the valency of Cr was 3+ as stated in the question!


On addition of ammonia for the last bit, I believe the complex formed to be: [Cr(NH3)4]3+, although this may be the short way of writing it.
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#22
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#22
when was chem mod 5????? i only did mod 4 ..
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#23
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#23
mod 5 woz on the same day as mod 4.
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#24
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#24
The answer to that cr questiion was ACID BASE becuase Chromium is Amphoteric.
Vin
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#25
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#25
About the Cr question, I personally think there was a slight mistake as the question did imply 2 distinct solutions. They would expect a "no reaction" only if they worded it like: "name the reaction, if any ..." Deprotonation is the reaction for the first part and the precipitate is Cr(OH)3. The second one should have been excess OH instead of ammonia, since the latter would result in a (remaining) precipitate and not a solution as required in the question. Thus I suspect an erratum. If it were excess OH, it would be [Cr(OH)6]3-, a green solution after redissolving.
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#26
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#26
that's what i thought too Vin, i wrote Cr(OH)6 3- and stated that this would occur in excess NaOH, and wrote "erratum?".. Well if it was we would get the marks for that question.... wooo.
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#27
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#27
continuing my post from above, i wrote that it was Amphothericity reaction assuming that it meant excess OH, but i dunno.....
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#28
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#28
You know that question about the bonding in Cr(NH3)6 , i know one type of bonding was dative covalent bonding, but what was the second??
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#29
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#29
covalent... there is covalent bonding within the water
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