Consider the following reaction: 2HgO \( \stackrel{\Delta}{\longrightarrow} \) 2Hg + O2 The respective state of HgO, Hg and O2 in the above reaction is
Understanding Physical States in Chemical Reactions
The question asks us to identify the physical states of the substances involved in the decomposition of Mercury(II) Oxide (\( \text{HgO} \)) upon heating. The reaction is given as:
\( 2\text{HgO} \stackrel{\Delta}{\longrightarrow} 2\text{Hg} + \text{O}_2 \)
In this reaction, Mercury(II) Oxide (\( \text{HgO} \)) is the reactant, and Mercury (\( \text{Hg} \)) and Oxygen (\( \text{O}_2 \)) are the products. We need to determine their respective states under the reaction conditions, which involve heating (\( \Delta \)).
Physical State of Mercury(II) Oxide (HgO)
Mercury(II) Oxide (\( \text{HgO} \)) is a compound formed from mercury and oxygen. At standard temperature and pressure, \( \text{HgO} \) exists as a solid. It is a reddish-orange or yellow crystalline powder.
The \( \Delta \) symbol above the arrow indicates that the reaction occurs when \( \text{HgO} \) is heated. While heating can cause substances to change state (e.g., melt), Mercury(II) Oxide decomposes into mercury and oxygen at temperatures below its melting point. Therefore, it is typically considered to be in the solid state when the decomposition begins.
- HgO: Solid state
Physical State of Mercury (Hg)
Mercury (\( \text{Hg} \)) is a chemical element, specifically a metal. Mercury is unique among metals because it is a liquid at room temperature and standard atmospheric pressure. This is a well-known property of mercury.
The reaction produces elemental mercury. Even though the reaction involves heating, the product mercury is formed and exists in its stable liquid state at the temperatures typically associated with this decomposition.
- Hg: Liquid state
Physical State of Oxygen (O₂)
Oxygen (\( \text{O}_2 \)) is a diatomic molecule and a chemical element. Oxygen is a gas at standard temperature and pressure.
In the decomposition of \( \text{HgO} \), oxygen is released as a gas. The gaseous state is indicated by \( \text{O}_2 \).
- O₂: Gas state
Summarizing the States
Based on the properties of the substances involved and the reaction conditions, the states are:
- Reactant \( \text{HgO} \): Solid
- Product \( \text{Hg} \): Liquid
- Product \( \text{O}_2 \): Gas
So, the respective states of \( \text{HgO} \), \( \text{Hg} \) and \( \text{O}_2 \) in the reaction are Solid, Liquid, and Gas.
Comparing with Options
Let's compare our findings with the given options:
- Option 1: Liquid, solid, gas (Incorrect - \( \text{HgO} \) is solid, \( \text{Hg} \) is liquid)
- Option 2: Solid, solid, gas (Incorrect - \( \text{Hg} \) is liquid)
- Option 3: Liquid, solid, liquid (Incorrect - \( \text{HgO} \) is solid, \( \text{Hg} \) is liquid, \( \text{O}_2 \) is gas)
- Option 4: Solid, liquid, gas (Correct - Matches our analysis)
Therefore, the correct option is Solid, liquid, gas.
Revision Table: Common Physical States
| Substance Type | Typical State at Room Temp (25°C) & 1 atm | Example |
|---|---|---|
| Ionic Compounds | Solid | NaCl (Sodium Chloride) |
| Most Metals | Solid (except Mercury) | Fe (Iron), Cu (Copper) |
| Mercury (Hg) | Liquid | Hg (Mercury) |
| Non-metal elements (e.g., O₂, N₂, H₂, Cl₂, F₂, Noble Gases) | Gas | O₂ (Oxygen), N₂ (Nitrogen) |
| Some Non-metal elements (e.g., Br₂, I₂) | Liquid (Br₂), Solid (I₂) | Br₂ (Bromine), I₂ (Iodine) |
| Water (H₂O) | Liquid | H₂O (Water) |
Additional Information on Chemical Reactions and States
Chemical equations often include symbols in parentheses after each chemical formula to indicate the physical state of the substance:
- (s) for solid
- (l) for liquid
- (g) for gas
- (aq) for aqueous solution (dissolved in water)
The decomposition of \( \text{HgO} \) could be written more formally as:
\( 2\text{HgO (s)} \stackrel{\Delta}{\longrightarrow} 2\text{Hg (l)} + \text{O}_2 \text{(g)} \)
This notation explicitly shows the states of matter involved in the reaction under the given conditions. Understanding the common states of different types of substances (elements, ionic compounds, molecular compounds) is crucial for interpreting chemical reactions.
Similar Questions
Directions: The following items consist of two statements, Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below:
Statement I: Oxygen gas is easily produced at a faster rate by heating a mixture of Potassium Chlorate and Manganese dioxide than heating Potassium chlorate alone.
Statement II: Manganese dioxide acts as a negative catalyst.
- Which one of the following is not an example of a redox reaction?
Which among the following is the correct arrangement of halogens in the increasing order of their oxidizing nature?
An iron nail dipped in copper sulphate solution turns brown. This is due to which one of the following types of reactions?
Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour?
Which one of the following is a chemical change?
Directions: The following items consist of two statements, Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below:
Statement I: The granules of modern gunpowder (also called black powder) are typically coated with Graphite.
Statement II: Graphite prevents the build-up of electrostatic charge.
Directions: The following items consist of two statements, Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below:
Statement I: Colour of Nitrogen dioxide changes to colourless at low temperature.
Statement II: At low temperature Nitrogen tetroxide (N 2O 4) is formed which is colourless.
Which one of the following species is NOT capable of showing disproportionation reaction?
On exposure to moist air, copper gains a green coat on its surface due to formation of which one of the following compound?
Important Questions from Chemical Reaction
Which of the following statement is/are true?
I. In physical change new substance is formed. substance is formed.
II. In chemical change no new substance is formed.
Which of the following cells involves similar chemical reactions?
The information not obtained from balanced chemical equation is
Oxygen cannot be obtained by which one of the following methods?
Which of the following statement is correct?
I. Insoluble salt is obtained by precipitation reaction.
II. Addition of oxygen or loss of hydrogen is called oxidation.
