Sg Chemistry - Topic 11: Metals

1. Complete the general word equation:

Metal + oxygen -->

The general word equation is used to represent a chemical reaction between a metal and oxygen. When a metal reacts with oxygen, it forms a metal oxide. This is because metals have a tendency to lose electrons and oxygen has a tendency to gain electrons. The metal oxide is a compound that contains both the metal and oxygen atoms bonded together.

Explanation

The general word equation is used to represent a chemical reaction between a metal and oxygen. When a metal reacts with oxygen, it forms a metal oxide. This is because metals have a tendency to lose electrons and oxygen has a tendency to gain electrons. The metal oxide is a compound that contains both the metal and oxygen atoms bonded together.

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2.

Name the gas produced during this reaction of metal + acid.

The gas produced during the reaction of metal + acid is hydrogen. Hydrogen gas is released when a metal reacts with an acid, such as hydrochloric acid or sulfuric acid. This is a common reaction known as a metal-acid reaction, where the metal displaces the hydrogen from the acid, resulting in the formation of hydrogen gas. The chemical formula for hydrogen gas is H2.

Explanation

The gas produced during the reaction of metal + acid is hydrogen. Hydrogen gas is released when a metal reacts with an acid, such as hydrochloric acid or sulfuric acid. This is a common reaction known as a metal-acid reaction, where the metal displaces the hydrogen from the acid, resulting in the formation of hydrogen gas. The chemical formula for hydrogen gas is H2.

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3. Stainless steel is used to make many useful objects like cutlery and sinks. It is made from a mixture of iron, chromium and nickel. What type of substance is stainless steel?

An alloy is a mixture of metals or metals with non-metals.

Explanation

An alloy is a mixture of metals or metals with non-metals.

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4. Choose the alloy from the selection given.

Copper

Brass

Magnesium

Plastic

Brass is a mixture of copper and zinc. It is used to make many objects including musical instruments.

Explanation

Brass is a mixture of copper and zinc. It is used to make many objects including musical instruments.

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6.

Place the metals in order of reactivity (most reactive first).

The correct answer is C A B. This means that metal C is the most reactive, followed by metal A, and then metal B. The order of reactivity is important because it determines how easily a metal can undergo chemical reactions. Metal C is the most reactive, meaning it is more likely to react with other substances compared to metal A and B. Metal A is less reactive than C but more reactive than B, and metal B is the least reactive of the three.

Explanation

The correct answer is C A B. This means that metal C is the most reactive, followed by metal A, and then metal B. The order of reactivity is important because it determines how easily a metal can undergo chemical reactions. Metal C is the most reactive, meaning it is more likely to react with other substances compared to metal A and B. Metal A is less reactive than C but more reactive than B, and metal B is the least reactive of the three.

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7. When magnesium reacts with sulphuric acid, which of the following word equations represents this reaction.

Magnesium + suphuric acid --> magnesium sulphide + water

Magnesium + suphuric acid --> magnesium sulphate + water

Magnesium + suphuric acid --> magnesium sulphide + hydrogen

Magnesium + suphuric acid --> magnesium sulphate + hydrogen

metal + acid --> salt + hydrogen

Explanation

metal + acid --> salt + hydrogen

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9. In what state(s) do metals conduct electricity?

Solid

Liquid

Gas

None of the above

Metals conduct electricity in both solid and liquid states. In the solid state, the metal atoms are closely packed together, allowing the free movement of electrons, which are responsible for conducting electricity. In the liquid state, the metal atoms are no longer in a fixed position, but they still retain their ability to conduct electricity due to the presence of free-moving electrons. In contrast, metals do not conduct electricity in the gas state because the atoms are too far apart and there is a lack of free electrons to carry the electric current.

Explanation

Metals conduct electricity in both solid and liquid states. In the solid state, the metal atoms are closely packed together, allowing the free movement of electrons, which are responsible for conducting electricity. In the liquid state, the metal atoms are no longer in a fixed position, but they still retain their ability to conduct electricity due to the presence of free-moving electrons. In contrast, metals do not conduct electricity in the gas state because the atoms are too far apart and there is a lack of free electrons to carry the electric current.

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10. Aluminum is used in the manufacture of aircraft parts. Which properties would be important for this use?

Electrical conductor

Thermal conductor

Low density

Ductile

Strong

The properties of low density and strength are important for the use of aluminum in the manufacture of aircraft parts. Low density allows the aircraft to be lightweight, which is crucial for fuel efficiency and maneuverability. Additionally, strength is necessary to ensure the structural integrity of the aircraft and withstand the stresses and forces experienced during flight. Therefore, aluminum's low density and strength make it an ideal material for aircraft parts.

Explanation

The properties of low density and strength are important for the use of aluminum in the manufacture of aircraft parts. Low density allows the aircraft to be lightweight, which is crucial for fuel efficiency and maneuverability. Additionally, strength is necessary to ensure the structural integrity of the aircraft and withstand the stresses and forces experienced during flight. Therefore, aluminum's low density and strength make it an ideal material for aircraft parts.

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