-1

Which of the following reactions doesn't represent an oxidation-reduction?

$$ \begin{align*} \ce{2 P + 5 HClO + 3 H2O &-> 2 H3PO4 + 5 HCl} \\ \ce{Zn + 2 HCl &-> ZnCl2 + H2} \\ \ce{Mg + CuSO4 &-> MgSO4 + Cu} \\ \ce{NaOH + HNO3 &-> NaNO3 + H2O} \end{align*} $$

I want to find which of those reactions is not an oxidation-reduction reaction, but I'm not sure how to do this and how to find the oxidation numbers, should I memorize them?

Is there some rules like when bases and acids react this can't be an oxidation-reduction reaction — the last reaction implies this — so I can know if the reaction is an oxidation-reduction reaction or not when I look at it without searching for every oxidation number?

Community
  • 1
Omar Mohamed Khallaf
  • 21
  • 5
  • Only the last one doesn't. This case can be solved trivially without memorizing anything as in the first three reactions an element is a reactant, and the fourth reaction is a neutralization reaction. But in general, yes, you need to memorize typical oxidation numbers of elements and charges of common anions and cations. – andselisk Jul 30 '19 at 12:34
  • @andselisk so if there is an element in the reactants, does this means that it must by an oxidation-reduction reaction? – Omar Mohamed Khallaf Jul 30 '19 at 14:55
  • 1
    If there is an element in the reactants and it is not an element in the products then yes, oxidation/reduction has occurred. – Waylander Jul 30 '19 at 14:58

1 Answers1

0

If there is an element in the reactants and it is not an element in the products then yes, oxidation or reduction has occurred.
Acid-base reactions are pretty much non-redox reactions. But it is always handy to learn the oxidations numbers.
Extra sources Do non-redox reactions exist?

Omar Mohamed Khallaf
  • 21
  • 5
Akil
  • 164
  • 8
  • 1
    "Well acid-base reactions are pretty much non-redox reactions".
    Do you mean that almost all acid-base reactions are non-redox or are you emphasizing that all acid-base reactions are non-redox reactions ?     – Omar Mohamed Khallaf Jul 30 '19 at 14:59
  • Well if you mean by acids, the species which give H+ ion in solution and by base, thes species which give OH- ion in solution, yes. I haven't known anything yet. However, it doesnot account for lewis base and lewis acids. – Akil Jul 30 '19 at 15:02
  • And i would add up to @Waylander. "Vice-versa" – Akil Jul 30 '19 at 15:15
  • I have just suggested an edit to contain both to accept it as an answer. – Omar Mohamed Khallaf Jul 30 '19 at 15:17