[millerst]

Hi All, once again I'm stuck. Here's the question.

Antimony is a grey metalloid. It is usually found in the mineral stibnite Sb₂S₃. Pure antimony can be obtained in either of two ways:
(i) Stibnite is reacted with iron
(ii) Two reaction occur
     1) Stibnite reacts with oxygen in a process called roasting, which forms antimony (IV) oxide (Sb₂O₄), and sulfur dioxide.
     2) The antimony (IV) oxide is then reacted with carbon to displace solid antimony from the compound.

a) Predict the products of the first method of extraction. Write a balanced chemical equation to represent the process. Classify the reaction.

b) Write a balanced equation for the process of roasting in the second method.

c) Predict the products of the second reaction of the second method, and represent the reaction in a balanced chemical equation. (Remember the whole goal is to obtain pure antimony.


My answers are:

a) Sb₂S₃ + Fe ---> FeS₃ + Sb₂
    **Single Displacement Reaction

b) Sb₂S₃ + 2O₂ ---> Sb₂O₄ + S₃

c) Sb₂O₄ + 4C₂ ---> 4C2O + Sb₂

Could someone point out any errors which I've made, thanks.

[Yggdrasil]

a) Sb₂S₃ + Fe ---> FeS₃ + Sb₂
    **Single Displacement Reaction

You are correct that it is a single displacement reaction.  However, I would write elemental antimony as Sb and not Sb₂.  Also, iron sulfide would be FeS for iron (II) sulfide or Fe₂O₃ for iron (III) sulfide.

b) Sb₂S₃ + 2O₂ ---> Sb₂O₄ + S₃

The products are ntimony (IV) oxide (Sb2O4), and sulfur dioxide

c) Sb₂O₄ + 4C₂ ---> 4C2O + Sb₂

Elemental carbon is C, and the oxide of carbon is not C₂O.

Also remember to balance your chemical equations.

[millerst]

Also, iron sulfide would be FeS for iron (II) sulfide or Fe₂O₃ for iron (III) sulfide.

How would you know which one to use, or are both correct if you use them to answer?

The products are ntimony (IV) oxide (Sb₂O₄), and sulfur dioxide

So the answer would be:   Sb₂S₃ + 5O₂ ---> Sb₂O₄ + 3SO₂

Elemental carbon is C, and the oxide of carbon is not C2O.

Sb₂O₄ + C₂ ---> 2CO₂+ 2Sb


Do those look about right then?

[DevaDevil]

Also, iron sulfide would be FeS for iron (II) sulfide or Fe₂S₃ for iron (III) sulfide.

How would you know which one to use, or are both correct if you use them to answer?

most iron sulfides are non-stoechiometric (Fe_1-xS). But in your case I would choose one and solve it for that. Iron (II) sulfide is more common, so just take that.

The products are ntimony (IV) oxide (Sb₂O₄), and sulfur dioxide

So the answer would be:   Sb₂S₃ + 5O₂ ---> Sb₂O₄ + 3SO₂

Elemental carbon is C, and the oxide of carbon is not C2O.

Sb₂O₄ + C₂ ---> 2CO₂+ 2Sb


Do those look about right then?

elemental carbon is C, not C₂, otherwize the products are fine (if there is plenty of oxygen availabe as well, else the product would be CO as well, not only CO₂)

[millerst]

Thanks loads I love this place.

One last question: In a single displacement reaction calcium chloride + iodine ---> iodine chloride + calcium

Or do these two produce no reaction?

[Yggdrasil]

I would assume there would be no reaction since elemental calcium is a pretty unstable substance.  If you really wanted to know how the reaction would proceed, you could look up the standard free energies of formation and calculate the Delta G for the reaction.  A highly positive Delta G would tell you that the reaction won't happen under normal conditions.

[DevaDevil]

as a simple displacement I would only expect
CaCl₂ (s) + I₂ (s) <--> CaI₂ (s) + Cl₂ (g),
but with the balance more towards the reactants than the products.