In an experiment magnesium hydroxide powder is added in 0.1 g portions to 25 cm3 of dilute hydrochloric acid until the magnesium hydroxide is just in excess. Universal indicator paper can be used to test the pH of the solution after each addition of magnesium hydroxide. State and explain how the pH changes as the magnesium hydroxide is added to the dilute hydrochloric acid. – 9019

2 thoughts on “In an experiment magnesium hydroxide powder is added in 0.1 g portions to 25 cm3 of dilute hydrochloric acid until the magnesium hydroxide is just in excess. Universal indicator paper can be used to test the pH of the solution after each addition of magnesium hydroxide. State and explain how the pH changes as the magnesium hydroxide is added to the dilute hydrochloric acid. – 9019”

1. When magnesium hydroxide is added to an acid, it increases the pH of the solution. This is because magnesium hydroxide is a base, and it works by reacting with the acid particles. The pH keeps increasing until it goes above 7, meaning the solution has become alkaline.

   The reason this happens is that magnesium hydroxide contains hydroxide ions (OH⁻). These react with the hydrogen ions (H⁺) from the acid. This is called a neutralisation reaction, where the acid is cancelled out by the base.

   After the reaction, there are fewer hydrogen ions left in the solution, because they have all reacted. If extra magnesium hydroxide is added, there will be an excess of hydroxide ions still in the solution, which makes the pH go above 7.

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2. When magnesium hydroxide is added to an acid, it increases the pH of the solution. This is because magnesium hydroxide is a base, and it works by reacting with the acid particles. The pH keeps increasing until it goes above 7, meaning the solution has become alkaline.

   The reason this happens is that magnesium hydroxide contains hydroxide ions (OH⁻). These react with the hydrogen ions (H⁺) from the acid. This is called a neutralisation reaction, where the acid is cancelled out by the base.

   After the reaction, there are fewer hydrogen ions left in the solution, because they have all reacted. If extra magnesium hydroxide is added, there will be an excess of hydroxide ions still in the solution, which makes the pH go above 7.

   Reply