Topic 7 - Properties Of Substances - Quiz, Flashcards & Trivia

1. Why does electrolysis not work, if the electrolyte used is sugar solution?

Sugar is covalent / has no ions

Sugar is not at the correct temperature

There must not be enough sugar in the solution.

For electrolysis to work, the electrolyte must be an ionic solution or melt, this allows the ions to complete the circuit. Sugar is covalent / does not have ions.

Explanation

For electrolysis to work, the electrolyte must be an ionic solution or melt, this allows the ions to complete the circuit. Sugar is covalent / does not have ions.

2. Non-metals do not conduct electricity. Which non-metal is the only exception?

Carbon (diamond)

Carbon (graphite)

Silicon

Chlorine

Graphite is the only non-metal that can conduct electricity. This is because graphite has a unique structure where its carbon atoms are arranged in layers that are loosely held together. This allows the free movement of electrons within the layers, enabling graphite to conduct electricity. Other non-metals, such as carbon in the form of diamond, silicon, and chlorine, do not have this structure and therefore cannot conduct electricity.

Explanation

Graphite is the only non-metal that can conduct electricity. This is because graphite has a unique structure where its carbon atoms are arranged in layers that are loosely held together. This allows the free movement of electrons within the layers, enabling graphite to conduct electricity. Other non-metals, such as carbon in the form of diamond, silicon, and chlorine, do not have this structure and therefore cannot conduct electricity.

3. During an electrolysis, what type of charged particle will flow through the wires?

Electolyte

Protons

Electrons

Ions

Ions are free to move in ionic solutions/melts. Electrons flow through wires.

Explanation

Ions are free to move in ionic solutions/melts. Electrons flow through wires.

4. What state is sodium sulphate likely to be at room temperature?

Solid

Liquid

Gas

Sodium sulphate is ionic. The attraction between oppositely charged ions is strong and known as the ionic bond. Ionic compounds have high melting and boiling points because the bond is hard to break.

Explanation

Sodium sulphate is ionic. The attraction between oppositely charged ions is strong and known as the ionic bond. Ionic compounds have high melting and boiling points because the bond is hard to break.

5. Which of the following will conduct electricity in the state shown.

NaOH(s)

CuCl2 (s)

Sugar (aq)

NaCl (aq)

Sugar is covalent - does not conduct electricity in any state.
NaOH, CuCl2 and NaCl are ionic. Ionic compounds conduct electricity when ions are free to move (in solution or melts)

Explanation

Sugar is covalent - does not conduct electricity in any state.
NaOH, CuCl2 and NaCl are ionic. Ionic compounds conduct electricity when ions are free to move (in solution or melts)

6.

Which ion electron equation, correctly identifies what is happening at the negative electrode.

Cu(s) --> Cu2+(aq) + 2e-

Cu2+(aq) + 2e- --> Cu(s)

2Cl-(aq) --> Cl2(g) + 2e-

Cl2(g) + 2e- --> 2Cl-(aq)

Cu2+(aq) ions are attracted to the negative electrode. Red brown copper metal is formed.

Explanation

Cu2+(aq) ions are attracted to the negative electrode. Red brown copper metal is formed.

7.

Which of the following statements is correct.

A.C. is used, as the products are easily identified,

D.C is used, to ensure that electricity flows.

D.C is used, as this allows the products to be identified.

DC (Direct current) - each electrode stays with the same charge. This allows the ions to move towards the oppositely charged electrode.

Explanation

DC (Direct current) - each electrode stays with the same charge. This allows the ions to move towards the oppositely charged electrode.

8. Grease is a covalent compound. Which of the following liquids is it likely to be soluble in?

Water

Hydrochloric acid

Petrol

Covalent substances are soluble in covalent liquids. Petrol is a covalent liquid, so grease should be soluble in it.

Explanation

Covalent substances are soluble in covalent liquids. Petrol is a covalent liquid, so grease should be soluble in it.

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

Solid

Liquid (melts)

Gas

In solid and molten metals the atoms are close together, outer energy levels overlap and electrons can move freely between the atoms. This is the reason for the high conductivity of metals.

Explanation

In solid and molten metals the atoms are close together, outer energy levels overlap and electrons can move freely between the atoms. This is the reason for the high conductivity of metals.

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10. There are a wide range of covalent compounds. Which state(s) do they exist?

Solid

Liquid

Gas

Covalent network compounds (eg Silicon dioxide) are solid at room temperature. They have strong covalent bonds that are very difficult to break, so m pt and b pt are very high.
Covalent molecules (eg water, carbon dioxide) exist as molecules and have no covalent bonds between the molecules so, they have lower m pt and b pts (tend to be liquids or gases at room temperature).

Explanation

Covalent network compounds (eg Silicon dioxide) are solid at room temperature. They have strong covalent bonds that are very difficult to break, so m pt and b pt are very high.
Covalent molecules (eg water, carbon dioxide) exist as molecules and have no covalent bonds between the molecules so, they have lower m pt and b pts (tend to be liquids or gases at room temperature).

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11. Which of the following would be the correct ionic formula for sodium sulphate?

A (Na⁺)₄(SO4 ^2-)₂ B Na₂SO₄ C (Na⁺)₂SO4 ^2- D Na₄SO₄₂

(Na+)4(SO4 2-)2

Na2SO4

(Na+)2SO4 2-

Na4SO42

Remember to add charges for ionic formula.
Sodium - group 1 - valency 1 - Na+
Sulphate - complex ion (data book) - SO4 2-(charge 2-/valency 2)

Explanation

Remember to add charges for ionic formula.
Sodium - group 1 - valency 1 - Na+
Sulphate - complex ion (data book) - SO4 2-(charge 2-/valency 2)