IGCSE Chemistry

[Lana19984]

HELPP (acid is a molecule or other species which can donate a proton or accept an electron pair in reactions.)

can someone please explain what does that mean ?? i mean donating a proton basically means donating the hydrogen right ? but the hydrogen also has an electron so why do we say a proton donor ? then we have the thing about accepting an electron pair , this is so confusing please explain it ??

 

[LONKBUCH]

Well first, most hydrogen atoms are made of only a single proton and electron (the most commonly found isotope).
When we have an acid such as HCl dissolved in water, it ionizes (forms ions) to give us H+ and Cl-. An H+ ion is a hydrogen atom that has lost an electron (that the chlorine atom has gained to form a chloride ion), so it is only a proton.
Now, when KOH reacts with HCl, it forms KCl and H2O.
KOH(aq) + HCl(aq) --> KCl(aq) + H2O(l).
If we split it into ions it looks like this:
K+(aq) + OH-(aq) + H+(aq) + Cl-(aq) --> K+(aq) + Cl-(aq) + H2O(l)
If we write it as an ionic equation (we eliminate the spectator ions, the ones that do not take part in the reaction, on both sides) , it is:
OH- + H+ --> H2O.
The acid has lost the hydrogen ion (in other words, donated it) and it was accepted by the OH- from the alkali. It also accepted the electron from the OH- and formed covalent bonds to form water.


In summary, a hydrogen ion is called a proton because a hydrogen atom is just a proton and an electron, so when it forms ions it loses the electron and becomes a lone proton. The acid gives the hydrogen ion/proton to the base, reacting with the OH- to form water, so it is called a proton donor and an alkali is called a proton acceptor, because it accepted the proton.

IF you have any more questions in chemistry, or need further explanation if you didn't understand my previous explanation feel free to ask.

 

[Lana19984]

Thank you so much , do you have an email i can contact you on ,when i have doubts ? that would be so helpful if not i will try to reach you there and thank you again

 

[LONKBUCH]

My email is [email protected]

 

[XxChampXx]

My email is [email protected]

Can you help me with question 1 part C of chemistry may june 2013 qp 61. The marking scheme says gas syringe does not work. But I don't understand why. Thank you in advance for your help

 

[LONKBUCH]

Can you help me with question 1 part C of chemistry may june 2013 qp 61. The marking scheme says gas syringe does not work. But I don't understand why. Thank you in advance for your help

Well if you look at the diagram that shows a collection of a gas in a gas syringe, the gas syringe only takes in gas from a small area, which is obviously not enough to cover the entire anode in the diagram seen in the question paper, that is why you cannot use a gas syringe.

 

[XxChampXx]

Well if you look at the diagram that shows a collection of a gas in a gas syringe, the gas syringe only takes in gas from a small area, which is obviously not enough to cover the entire anode in the diagram seen in the question paper, that is why you cannot use a gas syringe.

Thank you so much!!