Decomposition Reactions

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Questions and Answers

In a decomposition reaction, what happens to a single compound?

It remains unchanged, only absorbing energy.
It combines with another compound to form a complex substance.
It rearranges its atoms to form an isomer.
It splits into two or more simpler substances. (correct)

Which process is the opposite of a decomposition reaction?

Reduction
Oxidation
Combination (correct)
Neutralization

What is the primary purpose of heating ferrous sulphate crystals in the experiment?

To purify the crystals.
To change the color of the crystals without altering their composition.
To increase the mass of the crystals.
To initiate a decomposition reaction. (correct)

Why is it important to note the color of the ferrous sulphate crystals both before and after heating?

Color change is a visual indicator of a chemical change occurring. (A) Signup and view all the answers

What does the smell emitted during the heating of ferrous sulphate most likely indicate?

The formation of gaseous products from the decomposition. (C) Signup and view all the answers

Which of the following is NOT a typical product of the decomposition of ferrous sulphate?

Hydrogen gas (B) Signup and view all the answers

If a solid compound is heated and breaks down into two new substances, one solid and one gas, what type of reaction has occurred?

Decomposition (B) Signup and view all the answers

Why is it important to use a dry boiling tube in the experiment with ferrous sulphate crystals?

To prevent the ferrous sulphate from reacting with water. (C) Signup and view all the answers

What would be the most likely observation if the ferrous sulphate crystals were not heated sufficiently?

No noticeable change in the crystals. (A) Signup and view all the answers

How does the decomposition of food in our bodies relate to the concept of decomposition reactions in chemistry?

It breaks down complex molecules into simpler ones to release energy. (B) Signup and view all the answers

What is the primary reason for using a test tube holder when heating the boiling tube?

To protect your fingers from the heat. (C) Signup and view all the answers

Which of the following observations would best indicate that a decomposition reaction has taken place in the ferrous sulphate?

The formation of a brown solid and release of gases. (B) Signup and view all the answers

The decomposition of ferrous sulphate is an example of which type of reaction based on energy?

Endothermic (D) Signup and view all the answers

Suppose a student observes that after heating, the ferrous sulphate crystals turn black instead of brown. What might be a possible reason for this?

The ferrous sulphate was heated too strongly, leading to a different oxide. (B) Signup and view all the answers

Which of the following best differentiates a decomposition reaction from a single displacement reaction?

Decomposition involves a single reactant; single displacement involves two reactants. (A) Signup and view all the answers

During the decomposition of ferrous sulphate, if the evolved gases are bubbled through acidified potassium dichromate solution, what would be the expected observation?

The solution turns green. (B) Signup and view all the answers

If the experiment were performed in a humid environment, how might the results be affected?

The crystals may absorb moisture, affecting the decomposition. (B) Signup and view all the answers

What is the role of heat in the given decomposition reaction of ferrous sulphate?

It provides the energy required for bond breaking. (D) Signup and view all the answers

Which of the following laboratory safety measures is most important when performing the decomposition of ferrous sulphate?

Working under a well-ventilated area. (A) Signup and view all the answers

Which of the following equations best represents the balanced decomposition of hydrated ferrous sulphate ($FeSO_4 \cdot 7H_2O$) when heated?

$2FeSO_4 \cdot 7H_2O (s) \rightarrow Fe_2O_3(s) + SO_2(g) + SO_3(g) + 14H_2O(g)$ (B) Signup and view all the answers

If you wanted to test for the presence of $SO_2$ gas produced during the decomposition, which reagent would be most suitable?

Acidified potassium permanganate ($KMnO_4$) (A) Signup and view all the answers

A student performs the experiment and observes only the formation of a black residue with no noticeable gas evolution. What is the most likely explanation?

The temperature was not high enough to cause full decomposition. (C) Signup and view all the answers

Which of the following changes would increase the rate of decomposition of ferrous sulphate crystals?

Increasing the surface area of the crystals. (C) Signup and view all the answers

Consider a scenario where the evolved gases are passed over heated copper. What observation would confirm the presence of sulfur dioxide?

The copper turns black. (B) Signup and view all the answers

How does the decomposition of ferrous sulphate differ in a closed container versus an open container?

In a closed container, the evolved gases cannot escape, potentially increasing pressure and affecting the equilibrium. (B) Signup and view all the answers

Why might adding a small amount of manganese dioxide ($MnO_2$) to the ferrous sulphate before heating potentially change the outcome?

$MnO_2$ would catalyze a different decomposition pathway. (B) Signup and view all the answers

In a real-world application, how is the principle of thermal decomposition, similar to that observed with ferrous sulphate, used?

In the extraction of metals from their oxide ores. (D) Signup and view all the answers

If the student were to use ferrous chloride ($FeCl_2$) instead of ferrous sulphate ($FeSO_4$), what difference would they expect during thermal decomposition?

The products of decomposition would be different. (A) Signup and view all the answers

Which step is crucial for ensuring the accuracy of the experiment's observations?

Using a clean and dry boiling tube. (B) Signup and view all the answers

Why is it essential to observe the changes closely as the heating of ferrous sulphate progresses?

To identify intermediate products and assess the reaction's completeness. (A) Signup and view all the answers

A student heats ferrous sulphate in a crucible instead of a boiling tube. How might this impact the experimental results?

The products might react with the crucible material. (A) Signup and view all the answers

A chemist wants to slow down the thermal decomposition of ferrous sulfate. What might they change?

Decrease the temperature. (B) Signup and view all the answers

What implications might the thermal decomposition of ferrous sulphate have in geological processes?

It could contribute to the release of sulfur-containing gases into the atmosphere. (D) Signup and view all the answers

How could one modify the experimental setup to quantitatively measure the volume of gases released during the thermal decomposition of ferrous sulphate?

By connecting the boiling tube to a gas syringe. (D) Signup and view all the answers

Why do proteins, carbohydrates, and fats in our bodies undergo decomposition reactions?

To release energy. (B) Signup and view all the answers

In what way does the heating rate affect the decomposition process of ferrous sulphate crystals?

A slower heating rate ensures a more uniform decomposition, allowing for better observation of intermediate stages. (C) Signup and view all the answers

What is the most important reason to allow the boiling tube to cool down before handling it after the decomposition reaction?

To avoid thermal shock and potential burns. (A) Signup and view all the answers

If the laboratory lacked fume hood, what precautions would be most effective to ensure safety while conducting the experiment?

Performing the experiment near an open window and using a small fan to direct gases away from the face. (C) Signup and view all the answers

What are the substances initially involved in a chemical reaction called?

Reactants (A) Signup and view all the answers

Which type of reaction involves two or more substances combining to form a single, new compound?

Combination (D) Signup and view all the answers

During the experiment with ferrous sulphate, what is the initial color of the crystals before heating?

Light Green (C) Signup and view all the answers

What is the purpose of using a spatula in the experiment with ferrous sulphate?

To take a small quantity of ferrous sulphate crystals (C) Signup and view all the answers

What causes the color change of ferrous sulphate crystals from light green to white upon initial heating?

Formation of anhydrous ferrous sulphate (B) Signup and view all the answers

What are the gaseous products released during the decomposition of anhydrous ferrous sulphate?

Sulphur dioxide and sulphur trioxide (A) Signup and view all the answers

Which type of chemical reaction is represented by the heating of ferrous sulphate crystals?

Decomposition reaction (A) Signup and view all the answers

What is the final solid product formed after prolonged heating of ferrous sulphate crystals?

Ferric oxide (C) Signup and view all the answers

Why is it important to use a test tube holder during the heating process?

To avoid direct contact with the hot test tube (B) Signup and view all the answers

What is the primary hazard associated with inhaling sulphur dioxide and sulphur trioxide gases during the experiment?

Breathing difficulties (A) Signup and view all the answers

Which of the following observations indicates that anhydrous ferrous sulphate is further decomposing?

The formation of a dark brown solid. (C) Signup and view all the answers

What is the chemical formula of Ferrous Sulphate?

$FeSO_4$ (C) Signup and view all the answers

Which of the following is a characteristic property of sulphur dioxide gas released during the decomposition of ferrous sulphate?

Pungent smell (C) Signup and view all the answers

In the decomposition of ferrous sulphate, what type of bond is broken when water molecules are removed?

Covalent bond (D) Signup and view all the answers

During the heating of ferrous sulphate crystals, at what temperature range does the evolution of $SO_3$ gas typically become significant, assuming standard atmospheric pressure?

450-550°C (D) Signup and view all the answers

Which of the following changes observed after heating ferrous sulphate crystals suggests that both oxidation and reduction processes have occurred?

Evolution of a gas that turns acidified dichromate paper green (A) Signup and view all the answers

What is the oxidation state of iron (Fe) in ferric oxide ($Fe_2O_3$)?

+3 (D) Signup and view all the answers

Why is it necessary to perform the experiment in a dry boiling tube?

To provide a controlled environment for the reaction. (C) Signup and view all the answers

What type of change occurs when anhydrous ferrous sulphate is formed??

A physical change. (A) Signup and view all the answers

What are the products of thermal decomposition of $FeSO_4$?

$Fe_2O_3$, $SO_2$, $SO_3$ (B) Signup and view all the answers

In a displacement reaction, what happens to a compound?

One element replaces another in the compound. (B) Signup and view all the answers

What is the role of a double displacement reaction?

To exchange ions between two compounds. (D) Signup and view all the answers

What is the initial observation when $FeSO_4$ is heated?

The green crystals turns into white powder. (A) Signup and view all the answers

What is the purpose of ferrous sulfate crystals?

To observe the effect of heat on the compound. (C) Signup and view all the answers

After heating the ferrous sulphate the color changes to dark brown, why is this?

Due to the formation of ferric oxide. (B) Signup and view all the answers

Which substance is produced because of the loss of water molecules from the ferrous sulphate crystals upon heating?

Anhydrous ferrous sulphate. (B) Signup and view all the answers

Which of the following reactions takes place in an aqueous solution?

Double Displacement reaction (D) Signup and view all the answers

In the reaction of $FeSO_4$ when heated, what happens to the oxidation state of sulfur?

It increases in $SO_3$ and decreases in $SO_2$. (C) Signup and view all the answers

What is the correct order of the color changes?

Light green -> White -> Dark brown (B) Signup and view all the answers

Which of the following is a balanced equation for the decomposition?

$2FeSO_4 \rightarrow Fe_2O_3 + SO_2 + SO_3$ (B) Signup and view all the answers

The procedure mentions:

Labeling the Ferric Oxide. (B) Signup and view all the answers

What determines the classification of a chemical reaction?

The chemical changes taking place. (B) Signup and view all the answers

What can be dangerous when performing this experiment?

Inhaling sulphur dioxide and sulphur trioxide. (C) Signup and view all the answers

Which of the products of the reaction must be placed on a watch glass?

Ferric oxide. (D) Signup and view all the answers

Before heating the ferrous sulphate, what must you do?

Note down the color. (C) Signup and view all the answers

What is the name for two or more substances combining into a new compound?

Combination (A) Signup and view all the answers

What is the purpose of this experiment?

To observe the action of heat on ferrous sulphate crystals. (D) Signup and view all the answers

In a redox reaction involving ferrous sulphate decomposition, if $SO_2$ acts as a reducing agent, what is one likely product formed from its oxidation?

$SO_3$ (D) Signup and view all the answers

During the decomposition, a student notices the boiling tube cracks. What is an explanation for this?

The boiling tube was not dry. (B) Signup and view all the answers

If a student wants to collect the gas produced, what is the best method?

By downward displacement of air. (D) Signup and view all the answers

Flashcards

Decomposition Reaction

A reaction where a single compound breaks down into two or more simpler substances.

Combination Reaction

The reaction in which a substance is formed as a result of chemical combination.

Heating Ferrous Sulfate

When ferrous sulfate crystals are heated, they undergo thermal decomposition, producing gases and changing color.

Thermal Decomposition

Thermal decomposition involves using heat to break down a chemical compound into simpler substances.