In the reaction of magnesium metal with hydrochloric acid, how do you determine when the magnesium metal has reacted completely? select all that apply

in the reaction of magnesium metal with hydrochloric acid, how do you determine when the magnesium metal has reacted completely? select all that apply.

in the reaction of magnesium metal with hydrochloric acid, how do you determine when the magnesium metal has reacted completely? select all that apply.

Answer: In the reaction of magnesium metal (Mg) with hydrochloric acid (HCl), several observations can indicate that the magnesium has reacted completely. Here are some ways to determine when the reaction is complete:

  1. Bubbling or Effervescence: When magnesium reacts with hydrochloric acid, it produces hydrogen gas (H2) as one of the products. The appearance of bubbles or effervescence in the reaction flask indicates the evolution of hydrogen gas. When the bubbling stops, it can suggest that the reaction is complete.

  2. Dissolution of Magnesium: Magnesium metal will gradually dissolve in the hydrochloric acid as the reaction proceeds. As the magnesium dissolves completely and no solid magnesium remains, it indicates that the reaction has finished.

  3. Temperature Change: The reaction between magnesium and hydrochloric acid is exothermic, meaning it releases heat. If you feel the reaction flask getting warm during the reaction, it can indicate that the reaction is ongoing. When the temperature stabilizes and there is no further increase, it can signify completion.

  4. Color Change: In some cases, if the hydrochloric acid solution contains a pH indicator, you may observe a color change in the solution. The color change can be an indicator of the pH shift associated with the completion of the reaction.

  5. Gas Production: Besides the bubbles of hydrogen gas, you may also collect the evolved gas in a test tube and test it with a lit splint. If the gas ignites with a “pop” sound, it confirms the presence of hydrogen gas.

To be absolutely certain that the reaction is complete, it’s advisable to wait until all signs of reaction cease and then verify using one or more of the above methods. Always exercise caution when working with chemicals and perform experiments in a controlled environment.