# What are ionic equations?

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#1
Idk what ionic equations are and my science class is doing the higher tier and I don't get what it is and also I don't know what this means when they have 2+ at the end of Mg..
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1 year ago
#2
Ionic équations are chemical equations that show oxidation and reduction of species. But they don’t include spectator ions, only species that loses or gains electrons.
For example in the reaction Mg(s) + ZnSO4 (aq) —-> MgSO4(aq) + Zn(s) Magneisum has lost two electrons (oxidation), and zinc has gained two electrons (reduction). Mg(s) -> Mg 2+(aq) +2e- and Zn(aq) 2+ + 2e- -> Zn(s)
The sulphate ion (SO42-) hasn’t changed charge, so it’s not included. So the overall ionic equation is Mg(s) + Zn 2+ (aq) —-> Mg 2+ (aq) + Zn(s)
Last edited by Deggs_14; 1 year ago
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1 year ago
#3
Showing how electrons move between different ions. The 2+ refers to the charge of a Magnesium ion. It loses two electrons to a non-metal and therefore has 2 more protons than electrons, giving it a positive charge of 2+.
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1 year ago
#4
Magnesium starts off as a powder as a solid with no charge. But the aqueous zinc sulphate solution is ZnSO4(aq), an ionic compound with Zn2+ and SO42- ions. That’s where the Zn2+ comes from, as the zinc has lost two electrons, forming a positive charge.
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1 year ago
#5
Ionic equations show the reactions which occur between different ions which have dissociated in solution

For example, an acid-base reaction may look like this: HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
However, this is in aqueous conditions so everything separates into their ions... In ionic terms, it looks like this: H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) Na+(aq) + Cl-(aq) + H2O(l)
However, the spectator ions (the ions which appear on both sides of the equation and are hence unchanged throughout the course of the reaction) don't actually contribute to the reaction, so they cancel out on both sides to leave the overall ionic equation: H+(aq) + OH-(aq) H2O(l)
This shows that irrespective of what spectator ions you have, an acid-base reaction like above will occur in this way every single time, hence showing the primitive reaction between these ions

Of course, different types of reaction will have different ionic equations... But they all do the same thing, i.e. show the main reaction which occurs between different ions in solution

The 2+ at the end of Mg shows the charge of the magnesium ion, i.e. magnesium has lost two electrons to form an ion with a 2+ charge: Mg2+
Last edited by Kian Stevens; 1 year ago
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#6
(Original post by Tamimur)
Showing how electrons move between different ions. The 2+ refers to the charge of a Magnesium ion. It loses two electrons to a non-metal and therefore has 2 more protons than electrons, giving it a positive charge of 2+.
Thank you so much this makes a lot of sense to me now
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1 year ago
#7
(Original post by faatimahscoffee)
Idk what ionic equations are and my science class is doing the higher tier and I don't get what it is and also I don't know what this means when they have 2+ at the end of Mg..
Tamimur gives a nice simple summary here.
Last edited by Reality Check; 1 year ago
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#8
(Original post by Kian Stevens)
Ionic equations show the reactions which occur between different ions which have dissociated in solution

For example, an acid-base reaction may look like this: HCl(aq) NaOH(aq) NaCl(aq) H2O(l)
However, this is in aqueous conditions so the reactants separate into their ions... In ionic terms, it looks like this: H(aq) Cl-(aq) Na(aq) OH-(aq) Na(aq) Cl-(aq) H2O(l)
However, the spectator ions (the ions which appear on both sides of the equation and are hence unchanged throughout the course of the reaction) don't actually contribute to the reaction, so they cancel out on both sides to leave the overall ionic equation: H(aq) OH-(aq) H2O(l)
This shows that irrespective of what spectator ions you have, an acid-base reaction like above will occur in this way every single time, hence showing the primitive interaction between these ions

The 2 at the end of Mg shows the charge of the magnesium ion, i.e. magnesium has lost two electrons to form an ion with a 2 charge: Mg2
Ah thanks I think I get it: So spectator ions aren't relevant to the reaction. The 2 at the end of a symbol (like Mg) represents the charge of that Mg ion and also shows that Mg loses two electrons which gives it a positive charge with 2 less electrons than protons. Also the ions rearrange in the solution as they are free to move unlike in lattice conditions
Last edited by faatimahscoffee; 1 year ago
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1 year ago
#9
(Original post by faatimahscoffee)
Ah thanks I think I get it: So spectator ions aren't relevant to the reaction. The 2+ at the end of a symbol (like Mg) represents the charge of that Mg ion and also shows that Mg loses two electrons which gives it a positive charge with 2 more protons than electrons. Also the ions rearrange in the solution as they are free to move unlike in lattice conditions
Yes that's correct

An atom can lose or gain electrons, that's why they form ions
If an atom loses electrons, the resulting ion will have a positive charge as it'll have more protons than electrons; if an atom gains electrons, the resulting ion will have a negative charge as it'll have more electrons than protons
The number of electrons they lose/gain is what gives the charge a numerical value, e.g. Mg loses 2 electrons so forms a Mg2+ ion, or Cl gains 1 electron to form a Cl- ion, etc.
Last edited by Kian Stevens; 1 year ago
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