What happens when few pieces of zinc is added into a test tube containing dilut hydrochloric acid?
When a few pieces of zinc are added into a test tube containing dilute hydrochloric acid, a chemical reaction occurs. The zinc reacts with the hydrochloric acid to produce zinc chloride (ZnCl2) and hydrogen gas (H2). This is represented by the following equation:
Zn + 2HCl → ZnCl2 + H2
The hydrogen gas is released as bubbles, while the zinc chloride dissolves in the acid solution. The reaction is typically exothermic, meaning it produces heat.
Place a few pieces of zinc into some dilute nitric acid in a test tube. Does a reaction occur like that with hydrochloric acid? Explain.
When a few pieces of zinc are added into dilute nitric acid, a reaction occurs, but it is different from the reaction with hydrochloric acid. Nitric acid is a stronger oxidizing agent compared to hydrochloric acid. When zinc reacts with nitric acid, it undergoes a redox reaction.
The reaction can be represented by the following equation:
Zn + 2HNO3 → Zn(NO3)2 + H2O + NO2
In this reaction, zinc displaces hydrogen from nitric acid, resulting in the formation of zinc nitrate (Zn(NO3)2), water (H2O), and nitrogen dioxide (NO2). The nitrogen dioxide gas is reddish-brown in color and can be observed as a gas bubbling out of the reaction mixture.
It is important to note that nitric acid is a corrosive and strong oxidizing agent, so handling it should be done with caution.
When a few pieces of zinc are added to a test tube containing dilute hydrochloric acid, the following steps occur:
1. The dilute hydrochloric acid (HCl) dissociates into hydrogen (H+) ions and chloride (Cl-) ions.
2. The zinc metal (Zn) reacts with the hydrogen ions (H+) in the acid, leading to a displacement reaction. The zinc atoms lose electrons and are oxidized to form zinc ions (Zn2+):
Zn + 2H+ -> Zn2+ + H2
3. As a result of the displacement reaction, hydrogen gas (H2) is produced. The gas is released as bubbles in the solution and can be observed as effervescence.
4. The overall reaction is the combination of the two half-reactions mentioned above:
Zn + 2HCl -> ZnCl2 + H2
5. The zinc chloride (ZnCl2) formed during the reaction remains dissolved in the acid solution and may appear as a clear or slightly cloudy liquid.
Overall, the addition of zinc to dilute hydrochloric acid results in the production of hydrogen gas and the formation of zinc chloride in the solution.