Dinitrogen tetroxide, $$$\mathrm{N}_{2} \mathrm{O}_{4}$$$, decomposes into nitrogen dioxide, $$$\mathrm{NO}_{2}$$$. The reaction is reversible. $$\[ \begin{aligned} & \mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}_{2}(\mathrm{~g}) \\ & \text { colourless gas brown gas } \end{aligned} \]$$ Fig. 4.1 shows a gas syringe containing a mixture of dinitrogen tetroxide and nitrogen dioxide. The gas syringe is sealed. The mixture reaches equilibrium and the colour of the mixture of gases is a pale brown. Fig. 4.1 The pressure of the mixture is increased. All other conditions stay the same. The mixture immediately turns darker brown before the position of equilibrium changes. Explain in terms of particles why the mixture immediately turns darker brown. ..........................................................................................................................................

Chemistry

IGCSE&ALevel

CAIE

Exam No：0620_s24_qp_43 Year：2024 Question No：4(b)

Answer:

Knowledge points:

4.1.1. Define electrolysis as the decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current

4.1.10. Predict the identity of the products at each electrode for the electrolysis of a halide compound in dilute or concentrated aqueous solution

4.1.11. Construct ionic half-equations for reactions at the anode (to show oxidation) and at the cathode (to show reduction)

4.1.2.1. the anode as the positive electrode

4.1.2.2. the cathode as the negative electrode

4.1.2.3. the electrolyte as the molten or aqueous substance that undergoes electrolysis

4.1.3.1. molten lead(II) bromide

4.1.3.2. concentrated aqueous sodium chloride

4.1.3.3. dilute sulfuric acid using inert electrodes made of platinum or carbon / graphite

4.1.4. State that metals or hydrogen are formed at the cathode and that non-metals (other than hydrogen) are formed at the anode

4.1.5. Predict the identity of the products at each electrode for the electrolysis of a binary compound in the molten state

4.1.6. State that metal objects are electroplated to improve their appearance and resistance to corrosion

4.1.7. Describe how metals are electroplated

4.1.8.1. the movement of electrons in the external circuit

4.1.8.2. the loss or gain of electrons at the electrodes

4.1.8.3. the movement of ions in the electrolyte

4.1.9. Identify the products formed at the electrodes and describe the observations made during the electrolysis of aqueous copper(II) sulfate using inert carbon / graphite electrodes and when using copper electrodes

Answer:

Knowledge points:

Solution:

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