Chapter 8 Flashcards
(13 cards)
Give some examples of roasting
Some minerals are converted into oxide by heating up the air at a temperature below their melting points.
zinceblend (ZnS)
2ZnS + 3O2 —-^ 2ZnS + 2SO2
Cinnabar (HgS)
HgS + O2 —^ Hg + SO2
Give some examples of smelting
The method used to reduce metal ions to free metal. Most common reducing agents are coke, carbon monoxide, and hydrogen.
ZnO + C —^ Zn + CO
WO3 + 3H2 —^ W + 3H2O
How is copper smelted?
Two steps. Roasted ore is heated with coke and sand at 1100C. The materials separate into two layers, of which the bottom contains a mixture of Cu2S and FeS is called matte, while the upper layer is silicate slag formed by the reaction of FeO and sand.
2FeS + O2 —^ 2FeO + 2SO2
FeO + Si2 —^ FeSiO
Then it is bessemerized. Air is blown through the melted copper matte in a bessemer converter. Any remaining iron sulfide is oxidized and removed as slag. In the final smelting step, cuprous sulphide os oxidized to form cuprous oxide, which reacts with remaining cuprous sulphide to form metallic copper.
This is blistered copper, which is 97-98% copper, with trapped bubbles of SO2 gas. Bessemerization also turns iron into steal.
What is electro-refining?
Used to purify some impurities in smelted ore. An electrolytic cell is used in which impure metal acts as the anode and a sample of pure metal acts as a cathode i.e., electrolytic refining of copper ic carried out in an electrolytic tank containing an acidified copper sulphate solution. Impure copper is the anode and pure copper is the cathode.
when current is passed, impure copper dissolves into Cu^+12 ions, which gain electrons at cathode and form Cu atoms deposited on the cathode and then pure copper is collected. Impurities like Au and Ag fall off the anode as anode mud.
What is distillation?
This method is used for the purification of metals which possess a low boiling point such as mercury and zinc. In this process, the impure metal is heated above its boiling point so that it can form vapours. The impurities do not vaporise and hence they are separated.
What is the solvay process? what are its first few steps?
A continuous industrial process for obtaining sodium carbonate from limestone, ammonia, and brine.
Preparation of ammonia brine: gas is dissolved in brine, which is then fed into a carbonating tower.
In the carbonating tower, carbin dioxide is passed through the ammonia brine. The following reaction takes place in it
CO2 + NH3 + H2O —- NH4HCO
NH4HCO + NaCl —– NaHCO + NH4CL
Filtration: precipitates of NaHCO3 are separated from the milky solution by filtration. This is used as baking soda.
What are the final few steps of the solvay process?
Calcination: Sodium Hydrogen carbonate is heated to get sodium carbonate. Co2 is released in the process.
Prep of Co2 and slaked lime: Co2 is prodouced by heating limestone in a kiln.
CaCO3 ___heat___ CaO + CO2
Co2 is fed into the carbonating tower from the top. Equal amounts of lime and water are mixed to produce CaO.
Recovery of ammonia: Solution containing ammonium chloride produced in the tower is heated with slaked slime. Almost all the ammonia is recovered in this process. It is often reused.
What are the advantages of the solvay process>
Its cheap. Its raw minerals are easily available.
It is a pollution free process, no harmful pollutants are produced.
It consumes less fuel, because there is no solution to be evaporated.
C)2 and ammonia are recovered and reused.
It produces pure Sodium bicarbonate and Sodium Carbonate
What are fertilizer?
Compounds put into agricultural soil to provide nutrients to crops. classified into two categories:
Natural fertilizers from animal and human wastes.
Synthetic fertilizers like urea and phosphate.
some facts: Percentage of nitrogen is the highest among all synthetic nitrogen fertilizers.
It doesn’t affect soil texture.
In the soil, it hydrates quickly to ammonium carbamate which eventually changes into NH3, which decomposes into N2 and H2. Nitrogen is the main constituent of proteins; it is required by the stems and leaves during the early stages of plant development. It increases crop yielf and quality.
What is petroleum?
A viscous, energy-rich liquid derived from fossils underground. Name comes from the Latin words petro (rock) and oleum (oil). Its a thick oil mostly of hydrocarbons, containing significant amounts of ethane, propane, and butane.
it is drilled out of the ground. When a drill is passed through the rock, natural gas comes out first with great pressure.
what is slaked slime and how is it produced?
Ca(OH)2. Co2 is prodouced by heating limestone in a kiln.
CaCO3 \_\_\_heat\_\_\_ CaO + CO2
Co2 is fed into the carbonating tower from the top. Equal amounts of lime and water are mixed to produce Ca(OH)2.
CaO + H2O ___ Ca(OH)2
composition of petrroleum
mixture of hydrocarbons, particularly alkanes, cycloalkanes, and aromatic hydrocarbons. It may also contain compounds containing oxygen and nitrogen.
name two fuels not derived from petroleum
hydrogen fuel and biodiesel.
