Thermal decomposition

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Catatan pelajaran

What is Thermal Decomposition?

Thermal decomposition is a chemical reaction where a compound is heated and breaks down into smaller, simpler products.
It requires heat energy to break the chemical bonds in the compound.

Example: Copper Carbonate

Heating copper carbonate (green) produces copper oxide (black) and carbon dioxide gas.
Word equation: copper carbonate → copper oxide + carbon dioxide.
Symbol equation: CuCO₃ → CuO + CO₂.
The colour change from green to black is evidence of a chemical reaction.
The release of carbon dioxide gas is another sign of reaction.

General Rule for Metal Carbonates

When heated, a metal carbonate generally decomposes into a metal oxide and carbon dioxide.
Example: magnesium carbonate → magnesium oxide + carbon dioxide (MgCO₃ → MgO + CO₂).
Example: calcium carbonate → calcium oxide + carbon dioxide (CaCO₃ → CaO + CO₂).

Testing for Carbon Dioxide

Carbon dioxide gas turns limewater (calcium hydroxide solution) milky/cloudy white.
This is a positive test for carbon dioxide.

Example: Hydrogen Peroxide

Hydrogen peroxide decomposes into water and oxygen gas when heated.
Word equation: hydrogen peroxide → water + oxygen.
Balanced symbol equation: 2H₂O₂ → 2H₂O + O₂.

Testing for Oxygen

Oxygen gas will relight a glowing splint.
This is a positive test for oxygen.

Balancing Equations

Example: Silver oxide decomposes: 2Ag₂O → 4Ag + O₂ (balanced).
Always ensure the number of atoms of each element is equal on both sides.

Particle arrangement in solids, liquids, and gases. Thermal decomposition involves breaking bonds, often producing gases.

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1.What is thermal decomposition?
Easy
- AA reaction where a compound is heated and breaks down into simpler products
- BA reaction where two elements combine to form a compound
- CA reaction where a substance burns in oxygen
- DA reaction where a compound is broken down by electricity
2.When copper carbonate undergoes thermal decomposition, what are the products?
Easy
- ACopper oxide and carbon dioxide
- BCopper and carbon dioxide
- CCopper oxide and oxygen
- DCopper and oxygen
3.What colour change occurs when copper carbonate is heated?
Easy
- AFrom green to black
- BFrom black to green
- CFrom green to white
- DFrom white to black
4.Which test is used to confirm that a gas is carbon dioxide?
Easy
- ABubble the gas through limewater; it turns milky
- BHold a glowing splint near it; it relights
- CHold a lighted splint near it; it pops
- DCollect the gas in a test tube and smell it
5.Balance the equation: ___ Ag2O → ___ Ag + O2
Medium
- A2 Ag2O → 4 Ag + O2
- BAg2O → 2 Ag + O2
- C2 Ag2O → 2 Ag + O2
- D3 Ag2O → 6 Ag + O2
6.Which of the following is a sign that a chemical reaction has occurred when heating copper carbonate?
Easy
- AA colour change and gas release
- BOnly a colour change
- COnly gas release
- DNo change is observed
7.What is the balanced chemical equation for the thermal decomposition of hydrogen peroxide?
Medium
- A2 H2O2 → 2 H2O + O2
- BH2O2 → H2O + O2
- C2 H2O2 → H2O + 2 O2
- DH2O2 → 2 H2O + O2
8.What is the test for oxygen gas?
Easy
- AIt relights a glowing splint
- BIt turns limewater milky
- CIt burns with a squeaky pop
- DIt bleaches damp litmus paper

Soal lainnya

9.When a metal carbonate undergoes thermal decomposition, what are the general products?
Easy
- AMetal oxide and carbon dioxide
- BMetal and carbon dioxide
- CMetal oxide and oxygen
- DMetal and oxygen
10.In the reaction CaCO3 → CaO + CO2, what is the name of CaO?
Easy
- ACalcium oxide
- BCalcium carbonate
- CCalcium hydroxide
- DCalcium peroxide
11.Which of these is NOT a thermal decomposition reaction?
Medium
- A2Mg + O2 → 2MgO
- BCaCO3 → CaO + CO2
- C2H2O2 → 2H2O + O2
- DCuCO3 → CuO + CO2
12.If 50 g of calcium carbonate decomposes completely, what is the mass of calcium oxide produced? (Relative atomic masses: Ca=40, C=12, O=16)
Hard
- A28 g
- B22 g
- C50 g
- D56 g
13.A student heats 12.4 g of copper carbonate (CuCO3) strongly. After the reaction, the mass of the solid residue (copper oxide) is 8.0 g. What mass of carbon dioxide gas was released?
Medium
- A4.4 g
- B8.0 g
- C12.4 g
- D20.4 g
14.In an experiment, a sample of green copper carbonate is heated until it turns black. The gas produced is bubbled through limewater. What is the expected observation in the limewater?
Medium
- AIt turns milky/cloudy white
- BIt turns blue
- CIt remains colourless
- DIt turns red
15.A student heats 5.0 g of pure calcium carbonate (CaCO3) in a crucible until no further change. The mass of the residue (calcium oxide) is 2.8 g. What is the percentage mass of carbon dioxide in calcium carbonate? (Relative atomic masses: Ca=40, C=12, O=16)
Hard
- A44%
- B56%
- C28%
- D72%
16.Which of the following is the correct word equation for the thermal decomposition of magnesium carbonate?
Easy
- Amagnesium carbonate → magnesium oxide + carbon dioxide
- Bmagnesium carbonate → magnesium + carbon + oxygen
- Cmagnesium carbonate → magnesium oxide + carbon monoxide
- Dmagnesium carbonate → magnesium + carbon dioxide
17.A student investigates the thermal decomposition of three metal carbonates: copper carbonate, zinc carbonate, and sodium carbonate. Only copper carbonate and zinc carbonate decompose when heated strongly with a Bunsen burner. Sodium carbonate does not decompose. Which statement best explains this observation?
Medium
- ASodium carbonate is more thermally stable than copper and zinc carbonates
- BSodium carbonate decomposes at a lower temperature than the Bunsen burner provides
- CSodium carbonate does not contain carbonate ions
- DSodium carbonate produces a different gas
18.In the thermal decomposition of hydrogen peroxide, which test is used to identify the gas produced?
Easy
- AA glowing splint relights
- BLimewater turns milky
- CA burning splint extinguishes with a pop
- DDamp blue litmus paper turns red
19.A student heats 10.0 g of silver oxide (Ag2O) until it decomposes completely. The mass of silver metal left is 9.3 g. What is the mass of oxygen gas released?
Medium
- A0.7 g
- B9.3 g
- C10.0 g
- D19.3 g
20.What colour change is observed when copper carbonate is heated?
Easy
- AGreen to black
- BBlack to green
- CWhite to green
- DGreen to white
21.The balanced equation for the thermal decomposition of calcium carbonate is CaCO3 → CaO + CO2. If 50 g of calcium carbonate decomposes completely, what mass of carbon dioxide is produced? (Relative atomic masses: Ca=40, C=12, O=16)
Medium
- A22 g
- B28 g
- C44 g
- D50 g
22.Which of the following equations correctly represents the thermal decomposition of silver oxide?
Medium
- A2Ag2O → 4Ag + O2
- BAg2O → Ag + O2
- CAg2O → 2Ag + O
- D2Ag2O → 2Ag + O2
23.A student sets up an experiment to collect the gas produced from heating copper carbonate. Which method is most suitable for collecting carbon dioxide?
Medium
- ADownward delivery (upward displacement of air)
- BOver water (downward displacement of water)
- CIn a gas syringe
- DIn a test tube with a bung
24.The graph shows the mass of solid remaining when a sample of calcium carbonate is heated over time. Initially the mass is 10.0 g, and after 5 minutes it becomes constant at 5.6 g. What is the percentage of calcium oxide in the original sample?
Hard
- A56%
- B44%
- C5.6%
- D10%
25.A student heats a green powder in a test tube. The powder turns black, and a gas is produced that turns limewater milky. Which compound was most likely heated?
Medium
- ACopper carbonate
- BCalcium oxide
- CMagnesium oxide
- DSodium carbonate
26.In an experiment to collect the carbon dioxide produced from heating copper carbonate, which setup is most appropriate?
Medium
- AGas syringe
- BCollecting over water
- CUpward delivery
- DDownward delivery
27.A student heats 2.48 g of copper carbonate (CuCO3) until no further change. The mass of the residue is 1.60 g. What is the mass of carbon dioxide released? (Relative atomic masses: Cu=64, C=12, O=16)
Hard
- A0.88 g
- B0.44 g
- C1.60 g
- D0.96 g
28.Which of the following is a correct method to test for oxygen gas?
Easy
- ABubble the gas through limewater
- BHold a burning splint near the gas
- CHold a glowing splint near the gas
- DPass the gas over anhydrous copper sulfate
29.What is the word equation for the thermal decomposition of hydrogen peroxide?
Easy
- Ahydrogen peroxide → water + oxygen
- Bhydrogen peroxide → hydrogen + oxygen
- Chydrogen peroxide → water + hydrogen
- Dhydrogen peroxide → hydrogen oxide + oxygen
30.A student heats a sample of calcium carbonate and collects the gas produced. The gas is bubbled through limewater, which turns milky. Which gas is present?
Easy
- AOxygen
- BCarbon dioxide
- CHydrogen
- DNitrogen
31.In the thermal decomposition of silver oxide, the products are silver and oxygen. Which is the correct balanced equation?
Medium
- A2Ag2O → 4Ag + O2
- BAg2O → 2Ag + O2
- C2Ag2O → 2Ag + O2
- DAg2O → Ag + O2
32.What colour is copper oxide?
Easy
- AGreen
- BBlack
- CBlue
- DWhite
33.A student heats a white solid strongly. It decomposes to form a white solid and a gas that turns limewater milky. Which compound was heated?
Medium
- AZinc carbonate
- BCopper carbonate
- CSodium carbonate
- DCalcium oxide
34.A student heats 5.0 g of calcium carbonate in a crucible. After heating, the mass of the residue is 2.8 g. What is the percentage mass loss?
Medium
- A44%
- B56%
- C28%
- D72%
35.Which of the following is NOT a sign that a chemical reaction has occurred when heating copper carbonate?
Medium
- AColour change from green to black
- BRelease of a gas
- CTemperature increase
- DFormation of a precipitate
36.What is the test for carbon dioxide gas?
Easy
- AIt relights a glowing splint
- BIt turns limewater milky
- CIt burns with a pop
- DIt turns damp blue litmus red
37.Which of the following is a sign that thermal decomposition of copper carbonate has occurred?
Medium
- AColour change from green to black
- BFormation of a white precipitate
- CRelease of a gas that turns limewater purple
- DIncrease in mass of the solid
38.Complete the chemical equation: CaCO3 → ? + ?
Easy
- ACaO + CO2
- BCa + CO2
- CCaO + C
- DCa + O2 + C
39.Balance the equation: ? Ag2O → ? Ag + O2
Medium
- A2 Ag2O → 4 Ag + O2
- BAg2O → 2 Ag + O2
- C2 Ag2O → 2 Ag + O2
- DAg2O → Ag + O2
40.Balance the equation: 2H2O2 → ? H2O + O2
Medium
- A2
- B1
- C3
- D4
41.When a metal carbonate undergoes thermal decomposition, it always produces a metal oxide and carbon dioxide.
Easy
True or false?
42.Limewater turns milky when carbon dioxide is bubbled through it.
Easy
True or false?
43.In the thermal decomposition of hydrogen peroxide, the products are hydrogen and oxygen.
Easy
True or false?
44.Match each metal carbonate with the colour of its oxide after thermal decomposition.
Medium
- Copper carbonate
- Magnesium carbonate
- Calcium carbonate
- Black
- White
- White
45.Arrange the following steps in the correct order to test for carbon dioxide gas produced from thermal decomposition.
Medium
- Heat the metal carbonate in a test tube
- Pass the gas through limewater
- Observe the limewater turning milky
- Collect the gas using a delivery tube
46.Match each metal carbonate with the correct products of its thermal decomposition.
Medium
- Copper carbonate
- Calcium carbonate
- Magnesium carbonate
- Copper oxide + carbon dioxide
- Calcium oxide + carbon dioxide
- Magnesium oxide + carbon dioxide
47.Arrange the following steps in the correct order to test for carbon dioxide gas produced from thermal decomposition of copper carbonate.
Medium
- Heat copper carbonate in a test tube
- Bubble the gas through limewater
- Observe limewater turning milky
- Collect the gas using a delivery tube
48.Which of the following are signs that a chemical reaction has occurred during the thermal decomposition of copper carbonate? (Select all that apply)
Medium
- AColour change from green to black
- BRelease of a gas
- CTemperature decrease
- DFormation of a solid residue
49.What is the chemical formula of copper carbonate?
Easy
- ACuCO3
- BCuO
- CCaCO3
- DCO2
50.A student heats 2.48 g of copper carbonate (CuCO3) until no further change. The mass of the residue is 1.60 g. What is the mass of carbon dioxide released? (Relative atomic masses: Cu=63.5, C=12, O=16)
Hard
- A0.88 g
- B0.44 g
- C1.60 g
- D2.48 g
51.Complete the word equation:
Easy
copper carbonate → ____ + carbon dioxide
52.Complete the chemical equation for the thermal decomposition of calcium carbonate:
Easy
CaCO3 → ____ + ____
53.In the thermal decomposition of calcium carbonate (CaCO3), how many grams of calcium oxide (CaO) are produced from 100 g of calcium carbonate? (Relative atomic masses: Ca=40, C=12, O=16)
Medium
54.Complete the word equation for the thermal decomposition of hydrogen peroxide.
Easy
hydrogen peroxide → ____ + ____
55.Describe how you could test for oxygen gas produced during the thermal decomposition of hydrogen peroxide.
Medium
56.In the thermal decomposition of calcium carbonate (CaCO3), how many grams of calcium oxide (CaO) are produced from 100 g of calcium carbonate? (Relative atomic masses: Ca=40, C=12, O=16)
Medium
- A62 g
- B68 g
- C56 g
- D50 g

Catatan ulasan

## Thermal Decomposition **Definition:** Thermal decomposition is a chemical reaction where a compound is heated and breaks down into smaller, simpler products. ### Key Examples - **Copper carbonate:** \(\text{CuCO}_3 \rightarrow \text{CuO} + \text{CO}_2\) Green copper carbonate → black copper oxide + carbon dioxide. Signs of reaction: colour change (green to black) and gas release. - **Hydrogen peroxide:** \(2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2\) Produces oxygen gas. - **Metal carbonates** generally decompose into a metal oxide and carbon dioxide. ### Testing for Gases - **Carbon dioxide:** Pass gas through limewater (calcium hydroxide solution). If it turns milky/cloudy white, CO₂ is present. - **Oxygen:** Relights a glowing splint. ### Key Points - Thermal decomposition requires heat. - Products are simpler than the reactant. - Colour change and gas production indicate a chemical reaction.

Thermal decomposition: A chemical reaction where a compound is heated and breaks down into smaller and simpler products.
Limewater: A calcium hydroxide solution used to test for carbon dioxide; turns milky or cloudy white in the presence of CO₂.
Glowing splint test: A test for oxygen gas: if a glowing splint relights, oxygen is present.

Kartu flash

What is thermal decomposition?

Thermal decomposition is when a compound is heated and breaks down into smaller and simpler products.

What are the products when copper carbonate undergoes thermal decomposition?

Copper oxide and carbon dioxide.

Write the word equation for the thermal decomposition of copper carbonate.

copper carbonate → copper oxide + carbon dioxide

Write the balanced symbol equation for the thermal decomposition of copper carbonate.

CuCO3 → CuO + CO2

What colour is copper carbonate?

Green.

What colour is copper oxide?

Black.

What colour change occurs when copper carbonate decomposes?

Green to black.

How can you test for carbon dioxide gas?

Pass it through limewater (calcium hydroxide solution); it turns milky/cloudy white.

What is the general decomposition of a metal carbonate when heated?

A metal carbonate decomposes into a metal oxide and carbon dioxide.

What are the products when hydrogen peroxide undergoes thermal decomposition?

Water and oxygen.

Write the word equation for the thermal decomposition of hydrogen peroxide.

hydrogen peroxide → water + oxygen

How can you test for oxygen gas?

It will relight a glowing splint.

What is the reactant when magnesium carbonate undergoes thermal decomposition?

Magnesium carbonate.

What are the products of the thermal decomposition of magnesium carbonate?

Magnesium oxide and carbon dioxide.

Complete the chemical equation: MgCO3 → ?

MgCO3 → MgO + CO2

Complete the chemical equation for the thermal decomposition of calcium carbonate: CaCO3 → ?

CaCO3 → CaO + CO2

Balance: ? Ag2O → ? Ag + O2

2 Ag2O → 4 Ag + O2

Balance: 2H2O2 → ? H2O + O2

2H2O2 → 2 H2O + O2

Name two signs that a chemical reaction has occurred during thermal decomposition of copper carbonate.

Colour change (green to black) and release of a gas (carbon dioxide).

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