Question

Write a balanced equation for the preparation of (a) molecular oxygen, (b) ammonia, (c) carbon dioxide, (d) molecular hydrogen, (e) calcium oxide. Indicate the physical state of the reactants and products in each equation.

Short answer

The balanced equations show the preparation of O2 from H2O2, NH3 from N2 and H2, CO2 from C and O2, H2 from Zn and HCl, and CaO from CaCO3 decomposition.

Step-by-step solution

Molecular Oxygen (O2) Equation

Molecular oxygen can be prepared by the decomposition of hydrogen peroxide. The balanced chemical equation is:\[ 2 ext{H}_2 ext{O}_2 (aq) \rightarrow 2 ext{H}_2 ext{O} (l) + ext{O}_2 (g) \] In this reaction, hydrogen peroxide ( ext{H}_2 ext{O}_2) in an aqueous state decomposes into water ( ext{H}_2 ext{O}) in liquid form and molecular oxygen ( ext{O}_2) in gaseous form.

Ammonia (NH3) Equation

Ammonia can be synthesized through the Haber process, which involves nitrogen and hydrogen gases. The balanced chemical equation is:\[ ext{N}_2 (g) + 3 ext{H}_2 (g) \rightarrow 2 ext{NH}_3 (g) \]In this synthesis, nitrogen ( ext{N}_2) and hydrogen ( ext{H}_2), both in gaseous states, react under high pressure and temperatures to produce ammonia ( ext{NH}_3) gas.

Carbon Dioxide (CO2) Equation

Carbon dioxide can be generated by the combustion of carbon. The balanced chemical equation is:\[ ext{C} (s) + ext{O}_2 (g) \rightarrow ext{CO}_2 (g) \]Here, solid carbon ( ext{C}) burns in molecular oxygen ( ext{O}_2), a gas, to form carbon dioxide ( ext{CO}_2), also in gaseous form.

Molecular Hydrogen (H2) Equation

Molecular hydrogen can be produced by the reaction between zinc and hydrochloric acid. The balanced chemical equation is:\[ ext{Zn} (s) + 2 ext{HCl} (aq) \rightarrow ext{ZnCl}_2 (aq) + ext{H}_2 (g) \]In this reaction, solid zinc ( ext{Zn}) reacts with aqueous hydrochloric acid ( ext{HCl}) to produce zinc chloride ( ext{ZnCl}_2) in aqueous solution and molecular hydrogen ( ext{H}_2) gas.

Calcium Oxide (CaO) Equation

Calcium oxide is prepared by the thermal decomposition of calcium carbonate. The balanced chemical equation is:\[ ext{CaCO}_3 (s) \rightarrow ext{CaO} (s) + ext{CO}_2 (g) \]In this decomposition reaction, solid calcium carbonate ( ext{CaCO}_3) decomposes on heating to yield solid calcium oxide ( ext{CaO}) and carbon dioxide ( ext{CO}_2) gas.

Key concepts

Molecular Oxygen

Molecular oxygen is an essential element in various biological and chemical processes. It can be prepared through different chemical reactions, one common method being the decomposition of hydrogen peroxide. In the reaction, hydrogen peroxide \( \text{H}_2\text{O}_2 \) in aqueous solution breaks down into water \( \text{H}_2\text{O} \) and oxygen gas \( \text{O}_2 \). This is a classic example of a decomposition reaction where a single compound breaks down into two or more products. The balanced equation for this process is: \[ 2 \text{H}_2\text{O}_2 (aq) \rightarrow 2 \text{H}_2\text{O} (l) + \text{O}_2 (g) \] This reaction is often catalyzed by the enzyme catalase in biological systems or by manganese dioxide in laboratory settings. The oxygen evolved in this process is diatomic, meaning it consists of two oxygen atoms. Understanding this basic chemical process is crucial, as it lays the foundation for reactions involving oxygen in both natural and industrial applications.

Haber Process

The Haber process is a fundamental industrial method for the synthesis of ammonia \( \text{NH}_3 \). It involves the direct combination of nitrogen \( \text{N}_2 \) and hydrogen \( \text{H}_2 \) gases under specific conditions, including a high temperature and pressure, as well as the presence of a catalyst. The resulting ammonia is crucial for agricultural fertilizers and various chemical industries. The balanced equation is: \[ \text{N}_2 (g) + 3 \text{H}_2 (g) \rightarrow 2 \text{NH}_3 (g) \] This reaction is a prime example of a synthesis reaction, where two or more reactants combine to form a single product. It is named after Fritz Haber, who developed the process in the early 20th century. The Haber process has immense significance as it enables the large-scale production of ammonia, instrumental in supporting global food production.

Combustion Reaction

Combustion reactions are exothermic processes in which a substance reacts with molecular oxygen \( \text{O}_2 \), often producing heat and light. A classic example is the combustion of carbon, which combines with oxygen to produce carbon dioxide. The balanced equation for this reaction is: \[ \text{C} (s) + \text{O}_2 (g) \rightarrow \text{CO}_2 (g) \] In this type of reaction, carbon \( \text{C} \) in solid form reacts vigorously with oxygen gas \( \text{O}_2 \) to form carbon dioxide \( \text{CO}_2 \), which is also a gas. Combustion reactions are fundamental in energy production, such as in engines and power stations, where they are used to release energy from hydrocarbons. These reactions are essential for understanding the behavior of fuels and their environmental impacts.

Decomposition Reaction

Decomposition reactions are processes where a single compound breaks down into two or more simpler substances. A notable example involves the thermal decomposition of calcium carbonate \( \text{CaCO}_3 \), which yields calcium oxide \( \text{CaO} \) and carbon dioxide \( \text{CO}_2 \). The balanced chemical formula is: \[ \text{CaCO}_3 (s) \rightarrow \text{CaO} (s) + \text{CO}_2 (g) \] This reaction is crucial in industries such as cement and lime production, where calcium oxide is a primary component. It is important because it shows how heating provides the energy needed to split the bonds in \( \text{CaCO}_3 \), liberating \( \text{CO}_2 \) as a gas and leaving behind solid \( \text{CaO} \). Understanding decomposition reactions is fundamental in predicting the behavior of compounds under various conditions.

Synthesis Reaction

Synthesis reactions involve the combination of two or more simple substances to form a more complex compound. The reaction between nitrogen and hydrogen to form ammonia through the Haber process is a typical example. Another instance is the formation of water from hydrogen and oxygen. Synthesis reactions are represented as: \[ \text{A} + \text{B} \rightarrow \text{AB} \] In these reactions, different elements or compounds unite under certain conditions, indicating their importance in chemical manufacturing and biological systems. They often require energy input, such as heat or light, to overcome the activation energy barrier. Synthesis reactions are a backbone of chemistry, crucial for creating new materials and understanding molecular interactions.