Q22.34P - Chemistry: Molecular Nature Of Matter And Change

Question

One of the substances loaded into a blast furnace is limestone, which produces lime in the furnace. 

(a) Give the chemical equation for the reaction forming lime. 

(b) Explain the purpose of lime in the furnace. The term flux is often used as a label for a substance acting as the lime does. What is the derivation of this word, and how does it relate to the function of the lime?

(c) Write a chemical equation describing the action of lime flux.

Step-by-Step Solution

Answer

(a) The chemical equation for the reaction forming lime is :

${\text{CaCO}}_{3\left(s\right)}\stackrel{\mathrm{heat}}{\to } {\text{CaO}}_{\left(s\right)}{\text{+CO}}_{2\left(g\right)}$ 

(b) The lime (calcium oxide) reacts with ${\text{SiO}}_{\text{2}}$ present in the iron ore to produce ${\text{CaSiO}}_{\text{3}}$ slag. The word "flux" comes from the Latin word meaning"to flow." The liquid slag flows down to the bottom of the furnace and floats on the more dense iron.

${\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{SiO}}_{2\left(\mathrm{s}\right)} \stackrel{\mathrm{\Delta }}{\to }{\text{CaSiO}}_{3\left(\mathrm{I}\right)}$ 

(c) The chemical equation describing the action of lime flux is :

${\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{SiO}}_{2\left(\mathrm{s}\right)} \stackrel{\mathrm{\Delta }}{\to }{\text{CaSiO}}_{3\left(\mathrm{I}\right)}$ 

Step 1: Blast furnace

The blast furnace is a long cylindrical container made up of bricks. It can withstand intense heat.

Step 2:Subpart (a)

Solid calcium carbonate undergoes decomposition to give calcium oxide and carbon dioxide gas

${\text{CaCO}}_{3\left(s\right)}\stackrel{\mathrm{heat}}{\to } {\text{CaO}}_{\left(s\right)}{\text{+CO}}_{2\left(g\right)}$

Step 3: Subpart (b)

The lime (calcium oxide) reacts with ${\text{SiO}}_{\text{2}}$ present in the iron ore to produce ${\text{CaSiO}}_{\text{3}}$  slag. The word "flux" comes from the Latin word meaning"to flow." The liquid slag flows down to the bottom of the furnace and floats on the more dense iron.

${\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{SiO}}_{2\left(\mathrm{s}\right)} \stackrel{\mathrm{\Delta }}{\to }{\text{CaSiO}}_{3\left(\mathrm{I}\right)}$

Step 4: Subpart (c)

Calcium oxide reacts with ${\text{SiO}}_{\text{2}}$  present in the iron ore to produce  ${\text{CaSiO}}_{\text{3}}$ slag. The chemical equation is given by  

${\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{SiO}}_{2\left(\mathrm{s}\right)} \stackrel{\mathrm{\Delta }}{\to }{\text{CaSiO}}_{3\left(\mathrm{I}\right)}$