Chemistry Experiment Questions

We pour 100 ml of a hydrochloric acid solution 0.5 mol/L on a mass “m” of an alloy consists of silver, iron and zinc such that the reacting part of the alloy and all the acid disappear completely. The remaining mass is 0.9g of a solid and the number of moles of Fe2+ obtained is double that of Zn2+. Predict the reactions that occur and write the equation of these reactions.

• The reaction produces FeCl2 and ZnCl2 with Fe2+ moles double that of Zn2+

• The reaction produces only AgCl as a solid

• The reaction produces FeCl3 and ZnCl2 with equal moles of Fe2+ and Zn2+

• The reaction does not produce any solid

We pour 100 ml of a hydrochloric acid solution 0.5 mol/L on a mass “m” of an alloy consists of silver, iron and zinc such that the reacting part of the alloy and all the acid disappear completely. The remaining mass is 0.9g of a solid and the number of moles of Fe2+ obtained is double that of Zn2+. Determine the mass of each metal in the alloy. Deduce the mass of the alloy.

• The mass of silver is 0.5g, iron is 0.3g, and zinc is 0.2g. The total mass of the alloy is 1.0g.

• The mass of silver is 0.4g, iron is 0.4g, and zinc is 0.2g. The total mass of the alloy is 1.0g.

• The mass of silver is 0.3g, iron is 0.5g, and zinc is 0.2g. The total mass of the alloy is 1.0g.

• The mass of silver is 0.2g, iron is 0.6g, and zinc is 0.2g. The total mass of the alloy is 1.0g.

We pour 100 ml of a hydrochloric acid solution 0.5 mol/L on a mass “m” of an alloy consists of silver, iron and zinc such that the reacting part of the alloy and all the acid disappear completely. The remaining mass is 0.9g of a solid and the number of moles of Fe2+ obtained is double that of Zn2+. Determine the volume of the gas released.

• 22.4 L

• 11.2 L

• 5.6 L

• 2.8 L

We place a piece of chromium of mass 2.6g on the obtained solution in a way that a reaction occurs. What are the equations of the half reactions and the overall reaction?

• Cr → Cr³⁺ + 3e⁻; Cr³⁺ + 3e⁻ → Cr; Overall: Cr + 3e⁻ → Cr³⁺

• Cr → Cr²⁺ + 2e⁻; Cr²⁺ + 2e⁻ → Cr; Overall: Cr + 2e⁻ → Cr²⁺

• Cr → Cr³⁺ + 3e⁻; Cr³⁺ + 3e⁻ → Cr; Overall: Cr + 3e⁻ → Cr²⁺

• Cr → Cr²⁺ + 2e⁻; Cr²⁺ + 2e⁻ → Cr; Overall: Cr + 3e⁻ → Cr³⁺

We place a piece of chromium of mass 2.6g on the obtained solution in a way that a reaction occurs. Calculate the concentration of metal ions at the end of the reaction.

• 0.1 M

• 0.2 M

• 0.3 M

• 0.4 M

We place a piece of chromium of mass 2.6g on the obtained solution in a way that a reaction occurs. Calculate the mass of the deposit formed.

• 1.3g

• 2.6g

• 3.9g

• 5.2g