Question

Which of the following is produced when magnesium reacts with hot concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4} ?\) (a) \(\mathrm{H}_{2}\) (b) \(\underline{\underline{S}}\) (c) \(\mathrm{MgO}\) (d) \(\mathrm{SO}_{2}\)

Short answer

The correct product is (d) \(\mathrm{SO}_{2}\).

Step-by-step solution

Understand the Reaction

When magnesium (Mg) reacts with hot concentrated sulfuric acid (\(\mathrm{H}_{2}\mathrm{SO}_{4}\)), it is a redox reaction where magnesium acts as a reducing agent and the sulfur in sulfuric acid is reduced. This type of reaction often leads to the formation of sulfur dioxide (\(\mathrm{SO}_{2}\)).

Write the Balanced Chemical Equation

The reaction of magnesium with hot concentrated \(\mathrm{H}_{2}\mathrm{SO}_{4}\) can be represented by the equation:\[\text{Mg} + \text{2} \mathrm{H}_{2}\mathrm{SO}_{4} \rightarrow \text{MgSO}_{4} + \text{2} \mathrm{H}_{2}\mathrm{O} + \mathrm{SO}_{2}\]This indicates that sulfur dioxide is indeed formed as a product.

Identify the Correct Product

From the balanced chemical equation, it is evident that the main gaseous product formed is sulfur dioxide (\(\mathrm{SO}_{2}\)). Other products like magnesium sulfate (\(\mathrm{MgSO}_{4}\)) and water (\(\mathrm{H}_{2}\mathrm{O}\)) are also formed but are not listed in the options.

Choose the Correct Option

Based on the products obtained from the chemical reaction, we identify that option (d) \(\mathrm{SO}_{2}\) matches with the product sulfur dioxide formed during the reaction.

Key concepts

Magnesium Reactions

Magnesium is a highly reactive metal, especially when heated. It tends to lose electrons easily to form positive ions. This characteristic makes it a good reducing agent. When magnesium is involved in a chemical reaction, it typically reacts by undergoing oxidation - meaning, it loses electrons. This can be seen clearly when magnesium reacts with other substances like oxygen or acids.

• In a typical reaction with an acid, magnesium tends to displace hydrogen, because magnesium has a strong tendency to form a more stable ionic bond by giving up its electrons.
• However, when magnesium reacts with hot, concentrated sulfuric acid ( H2SO4 ), it leads to an exciting redox reaction. Here, the sulfur from the acid is reduced, while the magnesium is oxidized, eventually forming magnesium sulfate ( MgSO4 ) and releasing sulfur dioxide ( SO2 ) as a gas.
• This reaction is highly exothermic, meaning it releases heat, which makes handling it without appropriate safety measures quite hazardous.

Understanding the nature of magnesium reactions helps in predicting the outcomes of its interactions with various substances, especially acids.

Sulfuric Acid Reactions

Sulfuric acid ( H2SO4 ) is a powerful acidic and oxidizing agent commonly used in chemistry. It is a diprotic acid, meaning it can release two hydrogen ions (protons) in solution, which significantly contributes to its strong acidic nature.

• One interesting property of sulfuric acid is its ability to act as either a dehydrating agent or an oxidizing agent, depending on the conditions. For instance, while reacting with metals like magnesium, it tends to act more as an oxidizing agent.
• In concentrated form, sulfuric acid is particularly aggressive and can decompose or oxidize many different metals, resulting in the liberation of gases like SO2 and the formation of metal sulfates.
• Specifically, when combined with magnesium, sulfuric acid is reduced while the sulfur within it goes through a reduction process from its +6 oxidation state in H2SO4 to a +4 state in SO2 as this gas is evolved.

Comprehending the dual nature of sulfuric acid is crucial when predicting the products of its chemical reactions.

Chemical Equation Balancing

Balancing chemical equations is an essential skill in chemistry that ensures the conservation of matter, respecting the Law of Conservation of Mass. This law states that matter cannot be created or destroyed in an isolated system.

• In any given chemical reaction, the mass of the reactants must equal the mass of the products. This is done by ensuring that the number of atoms of each element is the same on both sides of the equation.
• For the reaction between magnesium (Mg) and sulfuric acid (H2SO4), the balanced chemical equation is: \[\text{Mg} + \text{2} \mathrm{H}_{2}\mathrm{SO}_{4} \rightarrow \text{MgSO}_{4} + \text{2} \mathrm{H}_{2}\mathrm{O} + \mathrm{SO}_{2}\smallskip \]
• This equation reveals:
  • One magnesium atom reacts with two molecules of H2SO4.
  • This results in the formation of one molecule of magnesium sulfate (MgSO4), two molecules of water (H2O), and one molecule of sulfur dioxide (SO2).
  Understanding how to balance chemical equations accurately is essential for predicting the quantities of products and reactants involved.