That Neap question

[Martoman]

The reaction in the test is clearly shown as a one way arrow. It is:



A magnesium ribbon is dropped into a beaker of dilute acid. It shows a graph that steadily increases then tapers off at time T.

In their solutions they say this means that the reaction has reached equilibrium.... but isn't it just that it has completed the forward reaction? So no equilibrium?

[fady_22]

Yeah, that question annoyed me.
The hydrogen is continually being released, causing there to be a constant net forward reaction. So I said that the reaction went to completion. As there can't be a net backwards reaction (as the hydrogen is released), I don't think you can say that it reached equilibrium.
Stupid NEAP.

[Blakhitman]

The reaction in the test is clearly shown as a one way arrow. It is:



A magnesium ribbon is dropped into a beaker of dilute acid. It shows a graph that steadily increases then tapers off at time T.

In their solutions they say this means that the reaction has reached equilibrium.... but isn't it just that it has completed the forward reaction? So no equilibrium?

THEIR ANSWER IS WRONG!!!!! it has to be.

Besides, pretty sure that reaction is irreversible.

[Mao]

Who says a complete reaction is not in equilibrium? Equilibrium is defined as when the system stops changing. You can achieve that by equal rates of both forwards and backwards reaction. Both of these rates can be finite (dynamic equilibrium), or zero (complete reaction).

It's just not a very 'orthodox' use of "equilibrium". It's not a good way of describing the situation, but it's not incorrect.