When magnesium is heated in air, the product formed is heavier than the original ribbon. On the other hand when potassium magnate (7) is heated in air, the product formed is light. Explain the different observation

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Explanation:

When magnesium is heated in air, the element combines with oxygen to form a compound known as magnesium oxide according to the following equation:

Hence, the product formed - a combination of magnesium and the oxygen component of air - is heavier than the original magnesium ribbon.

On the other hand, potassium manganate (7) is heated in air and decompose to form potassium manganate (6), manganate oxide, and oxygen gas according to the following equation:

Hence, the final product formed is lighter than the original product because oxygen gas has been evolved.

During the heating of magnesium in air, it gains mass with the addition of oxygen present in air to form the oxide. However, during the heating of potassium manganate (vii), it decomposes or breaks down to simpler products and oxygen gas is given off.

Explanation:

During the heating of magnesium in air, it gains mass with the addition of oxygen present in air to form the oxide.

The equation for the reaction is given below:

2Mg(s) + O2(g) ---> 2Mg0

The molar mass of the magnesium metal is 24.0 g while the mass of the magnesium oxide is 40.0 g. The total mass of the metal before heating is 24 × 2. + 32 = 48.0 g. The total mass after heating = 48 + 32 = 80.0 g. Therefore, there is an increase in mass.

However, during the heating of potassium manganate (vii), it decomposes or breaks down to simpler products and oxygen gas is given off. The equation for the reaction is given below;

2KMnO4(s) > K2MnO4(s) + MnO2(s) + O2(g)

With the evolution of oxygen gas, there's a loss in mass of potassium manganate (vii). Molar mass of KMnO4 is 158.0 g while the mass of K2MnO4 is 197.0 g and that of MnO2 is 87.0 g. The total mass on the right hand side is 2 × 158 = 316.0 g. The total mass on the left-hand side with the exception of the gas evolved is 284.0 g. Therefore, there is a loss in mass.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).