Lesson Worksheet: Extracting Metals Chemistry

In this worksheet, we will practice describing the various processes used to extract different metals from their ores.

Q1:

Copper is found in two types of ore: copper-rich and copper-poor ores. Which of the following is not a common industrial method for removing copper from its ores?

  • APhytomining, where plants draw in copper ions from the soil
  • BDisplacement with calcium, where the ore is mixed with molten calcium, generating solid copper and calcium salts
  • CSmelting by mixing with air at high temperatures
  • DBioleaching, where bacteria feed on components of the ore, producing soluble copper ions
  • ETreatment with sulfuric acid to produce a solution of copper sulfate

Q2:

One of the final steps of copper refining is electroplating copper onto a copper electrode. When the deposited copper comes from a copper sulfate solution, such as that produced from sulfuric acid leaching, the process is called electrowinning.

In electrowinning, a lead anode and a copper cathode are immersed in a bath of copper(II) sulfate, and a potential difference is applied.

What is the half-equation of the reaction that occurs at the cathode?

  • ACu()Cu()+esaq2+
  • BCu()+2eCu()2+aqs
  • CCu()Cu()+2esaq2+
  • D2H()+2eH()+2aqg
  • ECu()+eCu()2+aqs

What is the half-equation of the reaction that occurs at the anode?

  • A2OH()HO()+2e22aqaq
  • BHO()2H()+O()+2e2+2laqg12
  • C4OH()2HO()+O()+4e22aqlg
  • D2OH()+H()2HO(l)+2e22aqg
  • E2Cl()Cl()+2e2aqg

Q3:

Smelting of copper ores produces an impure material, which can be converted to pure copper using the electrolysis apparatus illustrated in the diagram. An electrical current causes the immersed cathode to be coated with pure copper, while less reactive impurities fall to the bottom of the cell.

What is the half-equation of the reaction taking place at the anode?

  • ACu()+eCu()2++aqaq
  • BCu()+2eCu()2+aqs
  • CCu()+eCu()+aqs
  • DCu()Cu()+2esaq2+
  • ECu()Cu()+esaq+

What is the half-equation of the reaction taking place at the cathode?

  • ACu()+eCu()+aqs
  • BCu()+eCu()2++aqaq
  • CCu()Cu()+2esaq2+
  • DCu()Cu()+esaq+
  • ECu()+2eCu()2+aqs

A 95.0 kg pure copper cathode has a surface area of 1.50 m2 and a density of 9.00 g/cm3. The cathode is electroplated with a layer of pure copper 2.00 mm in thickness. It is assumed that the cathode is coated evenly with copper and that coating has a negligible effect on the surface area of the cathode. What is the mass of the cathode after coating is complete?

Q4:

Which of the following ores contains the largest amount of copper, as a percentage of the total mass?

  • ACuFeS2
  • BCuS2
  • CCuS95
  • DCuS
  • ECuCO3

Q5:

Why must aluminum be extracted from its ore via electrolysis, whereas pure silver and gold nuggets can be found native in Earth’s crust?

  • APure aluminum deposits exist too far below the surface of Earth to be mined.
  • BAluminum is more reactive than silver and gold.
  • CSilver and gold are more abundant in Earth’s crust.
  • DSilver and gold do not conduct electricity.
  • EAluminum extraction via electrolysis is cheap.

Q6:

Which of the following statements explains the first stage of the process of bioleaching?

  • AAir is bubbled through a slurry created from low-grade metal ore and water.
  • BPlants capable of absorbing the metal ions are grown in soil containing low-grade metal ore.
  • CSpecialized bacteria are added to a solution of low-grade metal ore.
  • DSulfuric acid is added to low-grade metal ore to produce a solution of metal ions.
  • ELow-grade metal ore is heated to a very high temperature in a furnace.

Q7:

Which of the following equations shows the reaction that occurs when zinc blende is heated in excess air during the extraction of zinc?

  • A2Zn+O2ZnO2
  • B2ZnS+O2ZnO+2S2
  • C2ZnS+3O2ZnO+2SO22
  • DZnO+HOZn(OH)22
  • EZnO+COZn+CO2

Q8:

Metal X is extracted from its oxide ore by heating with carbon. Metal Y occurs naturally in Earth’s crust in its elemental form. Metal Z is extracted from its oxide ore by electrolysis.

Order these metals from least to most reactive.

  • AX > Y > Z
  • BY > Z > X
  • CZ > X > Y
  • DY > X > Z
  • EZ > Y > X

Q9:

In the 1900s, the Sainte-Claire Deville process was used to extract aluminum from aluminum chloride, as shown: AlCl+3Na3NaCl+Al3 However, the aluminum produced through this process was extremely expensive. Which of the following reasons did not contribute to the aluminum produced by this method being so expensive?

  • AIsolating sodium from sodium chloride via electrolysis was expensive.
  • BIt is difficult to maintain large currents of electricity in the 1900s.
  • CSodium metal is dangerous to handle.
  • DSodium metal is very soft.
  • ESodium metal is very reactive.

Q10:

By which of the following processes can copper be extracted from low-grade copper ore?

  1. Smelting
  2. Addition of sulfuric acid
  3. Phytomining
  4. Electrolysis
  5. Bioleaching
  6. Reduction with carbon
  • A1, 2
  • B3, 5
  • C1, 3
  • D4 only
  • E6 only

This lesson includes 3 additional questions for subscribers.

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