What would happen if #"HCl"# is added to a solution of cobalt (II) ions?

Answer 1

The green complex #sf([CuCl_4]^(2-))# is formed.

I am assuming we are in aqueous conditions.

The aqueous copper(II) ion consists of a central #sf(Cu^(2+))# ion surrounded by 6 #sf(H_2O)# ligands:

It has the formula #sf([Cu(H_2O)_6]^(2+))# and is blue in colour. In solution it looks like this:

If a large excess of chloride ions is added the water ligands are displaced as the following equilibrium is established:

#sf([Cu(H_2O)_6]^(2+)+4Cl^(-)rightleftharpoonsCuCl_4^(2-)+6H_2O)#

#stackrel(color(white)(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx))(color(blue)(rarr)#

#sf(" "color(blue)(blue)" "color(green)(green))#

Concentrated hydrochloric acid contains a large amount of chloride ions so Le Chatelier's Principle tells us that adding this will cause the position of equilibrium to shift to the right producing green #sf(CuCl_4^(2-))# ions.

They have a tetrahedral structure:

The solution looks like this:

If excess water is now added the position of equilibrium is driven back to the left and the blue colour returns.

#sf([Cu(H_2O)_6]^(2+)+4Cl^(-)rightleftharpoonsCuCl_4^(2-)+6H_2O)#

#stackrel(color(white)(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx))(color(blue)(larr)#

#sf(" "color(blue)(blue)" "color(green)(green))#

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Answer 2

Cobalt (II) chloride (CoCl2) would form if HCl were added to a solution containing cobalt (II) ions. This is because the reaction between HCl and cobalt (II) ions would produce cobalt (II) chloride and hydrogen gas, with the chemical equation for this reaction being Co^2+ (aq) + 2 HCl (aq) → CoCl2 (aq) + H2 (g)

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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