singledisplacementalight

=Single Displacement=

In single displacement, one element takes the place of a less reactive element in a molecule.

That basically means; you have a compound and a single element reacting, and the element swaps with a less reactive element in the compound. so the basic equation would be:

A + BC --> B + AC

see? all that happens is one element switches. its a bit more complicated to balance than decomp or synthesis, but its no too bad.

lets try... **iron** //and// **hydrogen chloride** __reacting to form__ **iron chloride** //and// **hydrogen.**

or

Fe + HCl --> FeCl + H

okay, now we need to balance it.

we know first off H is a diatomic atom from H20, so we can add that in

Fe + HCl --> FeCl + H2

and the charge of H is +1 and Cl is -1, so doing the switcheroo they HCl is fine the way it is... but the charge of Iron is +3, and Cl is -1. so doing the switcheroo we need FeCl3 there.

Fe + HCl --> FeCl3 + H2

Okay... the molecules are all balanced! done! but just for safteys sake lets check it over

What? oh, we forgot to balance the equation!
 * (element) || Reactants || Products ||
 * Fe || 1 || 1 ||
 * H || 1 || 2 ||
 * Cl || 1 || 3 ||

Well we can just add a 3 to HCl to get the three Cl's we need.

Fe + 3HCl --> FeCl3 + H2

Off by one! looks like we will need to find the lowest common mutiple between 2 and 3. Thats 6, so we should just use a 6 instead of a three in HCl. which means we will need six Cl on the right, better multiply FeCl3 by 2 as well... and we will need 6 hydrogens on the right, so H2 by three should do it.
 * (element) || Reactants || Products ||
 * Fe || 1 || 1 ||
 * H || 3 || 2 ||
 * Cl || 3 || 3 ||

Fe + 6HCl --> 2FeCl3 + 3H2

Done! lets check it one more time...

Oh! we forgot to balance iron! oh well its isolated on the left so we can just add a 2 to it and be done with it. the final equation would be:
 * (element) || Reactants || Products ||
 * Fe || 1 || 2 ||
 * H || 6 || 6 ||
 * Cl || 6 || 6 ||

2Fe + 6HCl --> 2FeCl3 + 3H2


 * (element) || Reactants || Products ||
 * Fe || 2 || 2 ||
 * H || 6 || 6 ||
 * Cl || 6 || 6 ||

finally, done and balanced.

remember when i said before in the very beginning that it switches because one is more reactive? Well all elements have different levels of reactivity. Needless to say you will not need to memorize these, however you will need to understand why it happens.

A less reactive element is less likely to keep its spot in the compound when a more reactive element comes around because a less reactive one doesn't want to be in a molecule as much as a highly reactive element. Thats it.

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