Ive only just found it on a 2011 paper but its not in my revision guide, do we have to know the reaction of halogens with cyclohexane? if so can anyone tell me what they are
yeah you do, a Cl2 turns the organic solvent layer light green, Br2 turns it orange and I2 turns it purple
The book only says because it's a compromise between the physicists and chemists as they were originally using different oxygen isotopes. But they are unlikely to ask why
Don't take my word for it, but I think it's because carbon-12 is a stable isotope of carbon and it is rarely found as an other isotope. As opposed to other elements where different isotopes may be more common.
Don't take my word for it, but I think it's because carbon-12 is a stable isotope of carbon and it is rarely found as an other isotope. As opposed to other elements where different isotopes may be more common.
Yh. Think you're right. I would of gone with its the most abundant isotope of carbon.
The question is: Suggest the formula of sodium chlorate(VII).
I know its something to do with oxidation numbers... or something... :P
I think it's NaCl04, because we know the chlorine has an oxidation number of 7. Chlorate means it is made up of chlorine and oxygen, and oxygen commonly has an oxidation number of 2. So in order to get an overall oxidation number of -1 (so that it reacts with the Na 1+ ion). There needs to be 4 oxygens.
I think it's NaCl04, because we know the chlorine has an oxidation number of 7. Chlorate means it is made up of chlorine and oxygen, and oxygen commonly has an oxidation number of 2. So in order to get an overall oxidation number of -1 (so that it reacts with the Na 1+ ion). There needs to be 4 oxygens.
Ahhh yes I get it, thanks.
Also, I hate the questions where it states two elements such as Magnesium and chlorine, and then says that magnesium's melting point is higher... Then it asks you to explain why. I understand that magnesium has metallic bonding, and chlorine has covalent bonding... but how do I know whether or not it has giant covalent or simple covalent.
And why does the mark scheme say that only the Cl has van der waals? I thought all molecules had van der waals...
Fluorine exists as a simple molecule. So there are only weak van der waal's forces between molecules which are weak and require a small amount of energy to break.
NF3 has permanent dipoles because Fluorine is more electronegative than Nitrogen. So it attracts the shared pair of electrons more creating a permanent dipole. The overall molecule is polar therefore since NF3 has an unsymmetrical shape and the dipoles would not cancel each other out.
The question is: Suggest the formula of sodium chlorate(VII).
I know its something to do with oxidation numbers... or something... :P
Yeah, the Roman numerals refer to the oxidation state of the chlorine. Oxygen has an oxidation state of -2 and sodium has an oxidation state of +1. So it must be the chlorine that has a +7 oxidation state. And, as it's neutral overall, the formula would be... Hope that helped!
Kind of worrying about this exam. It's a resit from January for me. I'm worried because I understand all of this stuff but only managed a C in the exam. Going through past papers, I can see nothing that poses a huge threat, but my confidence isn't there purely based on my performance in January. Here's hoping my exam technique is good enough now for me to be able to answer the questions better.
EDIT: dammit, late to this party :P Hope it helped alongside everyone else's answers, haha! Good practice for me, too