Question

If \(0.750 \mathrm{~g}\) of orange mercury oxide decomposes to \(0.695 \mathrm{~g}\) of liquid mercury and oxygen gas, what is the mass of oxygen produced?

Short answer

The mass of oxygen produced is 0.055 g.

Step-by-step solution

Understanding the Problem

We are given that 0.750 g of orange mercury oxide decomposes into 0.695 g of liquid mercury and some amount of oxygen gas. The goal is to find the mass of oxygen gas produced in this decomposition.

Identify Known Quantities

From the problem, we know: - Total mass of mercury oxide (HgO) before decomposition: 0.750 g - Mass of liquid mercury after decomposition: 0.695 g

Apply Conservation of Mass

According to the law of conservation of mass, the total mass of reactants before the reaction should equal the total mass of products after the reaction.

Calculate the Mass of Oxygen Produced

Since the total mass of HgO decomposed (0.750 g) must equal the sum of the masses of mercury and oxygen produced, we find the mass of oxygen by subtracting the mass of mercury from the initial mass of HgO:\[\text{Mass of oxygen} = \text{Mass of HgO} - \text{Mass of mercury} = 0.750 \text{ g} - 0.695 \text{ g} = 0.055 \text{ g}\]

Verify the Solution

Ensure that the calculated mass of oxygen (0.055 g) along with the mass of mercury (0.695 g) adds up to the initial mass of mercury oxide, confirming the conservation of mass:\[0.055 \text{ g (oxygen)} + 0.695 \text{ g (mercury)} = 0.750 \text{ g (HgO)}\]

Key concepts

Chemical Decomposition

Chemical decomposition is a type of chemical reaction where one compound breaks down into two or more simpler substances. It is a common process that is often initiated by heat, light, or electricity. When a compound undergoes decomposition, it essentially rearranges its atomic components into differently structured products.
- For example, when mercury oxide decomposes, it separates into elemental mercury and oxygen gas. - This process is distinct from synthesis reactions, where simpler substances combine to form more complex compounds.
To understand these reactions better, keep in mind:

• Decomposition reactions usually absorb energy because breaking bonds requires energy input.
• They are often endothermic, meaning they absorb heat from their surroundings.
• Decomposition is essential in processes like digestion and even in everyday scenarios like the decomposition of organic matter in nature.

In the instance of mercury oxide, the decomposition is essentially a chemical transformation that simplifies the compound into its elemental parts.

Mercury Oxide

Mercury oxide, known by its chemical formula HgO, is a compound composed of mercury and oxygen. This compound usually appears as a bright red or orange solid.
- Mercury oxide is often used in scientific demonstrations due to its unique physical characteristics and ease of decomposition. - In the decomposition process, when heated, mercury oxide breaks down into liquid mercury and oxygen gas.
Some key points about mercury oxide include:

• Its decomposition was pivotal in the discovery of oxygen in the 18th century by Joseph Priestley.
• Mercury oxide exists in two forms: red and yellow (though color doesn't affect its decomposition similarly).
• The process of decomposition illustrates the conservation of mass, which means the mass before and after the reaction remains the same.

When handling mercury oxide, one should take precautions as mercury and its compounds can be toxic if not handled properly.

Mass Calculation

Mass calculation involves using the law of conservation of mass to determine the outcomes of chemical reactions. In the decomposition of mercury oxide, we can calculate the mass of products formed by understanding that the mass of reactants equals the mass of the products.
- This is based on the principle that matter is neither created nor destroyed in a chemical reaction.- In our example, 0.750 g of mercury oxide decomposes. Knowing 0.695 g of liquid mercury is produced, we use the law of conservation to find the missing mass.
To calculate:

• Initial mass of mercury oxide: 0.750 g.
• Final mass of mercury: 0.695 g.
• Mass of oxygen can be found by subtracting the mass of mercury from the initial mass of mercury oxide:\[\text{Mass of Oxygen} = 0.750 \text{ g} - 0.695 \text{ g} = 0.055 \text{ g}\]

This simple subtraction gives the mass of the oxygen produced during the chemical decomposition of mercury oxide. Such calculations are fundamental in chemistry and help predict product outcomes precisely in any reaction.