What is the shape of an ammonia (NH₃) molecule? (d) The following equation shows the heat of reaction for the formation of benzene: $$C(s) + \frac{3}{2}H_2(g) \rightarrow C_6H_6(l) \qquad \Delta H = 49.1 \text{ kJ mol}^{-1}$$ Is this reaction exothermic or endothermic? Explain your answer. (e) A thin stream of liquid is attracted towards a charged plastic rod as shown on the right. What does this test tell you about the type of bonding in the liquid? (f) Why is chlorine added to the water in swimming pools? (g) Which of the following particles carry the electric current through a solution during electrolysis? atoms electrons electrons ions molecules (h) Name the type of nuclear radiation that consists of positively-charged particles that are identical to helium nuclei. (i) Calculate the percentage by mass of sulfur in sulfur trioxide (SO₃).

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What is the shape of an ammonia (NH₃) molecule? (d) The following equation shows the heat of reaction for the formation of benzene: $$C(s) + \frac{3}{2}H_2(g) \rightarrow C_6H_6(l) \qquad \Delta H = 49.1 \text{ kJ mol}^{-1}$$ Is this reaction exothermic or endothermic? Explain your answer - Leaving Cert Chemistry - Question c - 2014

Question c

$What-is-the-shape-of-an-ammonia-(NH₃)-molecule?--(d)-The-following-equation-shows-the-heat-of-reaction-for-the-formation-of-benzene:--$$C(s)-+-\frac{3}{2}H_2(g)-\rightarrow-C_6H_6(l)-\qquad-\Delta-H-=-49.1-\text{-kJ-mol}^{-1}$$--Is-this-reaction-exothermic-or-endothermic?-Explain-your-answer-Leaving Cert Chemistry-Question c-2014.png$

What is the shape of an ammonia (NH₃) molecule? (d) The following equation shows the heat of reaction for the formation of benzene: $$C(s) + \frac{3}{2}H_2(g) \rig... show full transcript

Worked Solution & Example Answer:What is the shape of an ammonia (NH₃) molecule? (d) The following equation shows the heat of reaction for the formation of benzene: $$C(s) + \frac{3}{2}H_2(g) \rightarrow C_6H_6(l) \qquad \Delta H = 49.1 \text{ kJ mol}^{-1}$$ Is this reaction exothermic or endothermic? Explain your answer - Leaving Cert Chemistry - Question c - 2014

Step 1

What is the shape of an ammonia (NH₃) molecule?

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Answer

The shape of an ammonia (NH₃) molecule is trigonal pyramidal. This is due to the presence of one lone pair of electrons on the nitrogen atom, which causes the three hydrogen atoms to be pushed closer together. This results in a bond angle of approximately 107 degrees.

Step 2

Is this reaction exothermic or endothermic? Explain your answer.

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Answer

The given reaction is endothermic. This is indicated by the positive value of \Delta H = 49.1 kJ mol^{-1}, which means that energy is absorbed during the reaction. In exothermic reactions, \Delta H would be negative, indicating that energy is released.

Step 3

What does this test tell you about the type of bonding in the liquid?

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Answer

The attraction of the liquid towards the charged plastic rod indicates that the liquid has polar bonding. This is because polar molecules have a positive and a negative end, allowing them to be influenced by an external electric field.

Step 4

Why is chlorine added to the water in swimming pools?

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Answer

Chlorine is added to swimming pool water primarily as a disinfectant. It kills harmful bacteria and microorganisms, ensuring the water remains clean and safe for swimming.

Step 5

Which of the following particles carry the electric current through a solution during electrolysis?

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Answer

The particles that carry electric current through a solution during electrolysis are ions. These charged particles move towards the electrodes, allowing the flow of electric current.

Step 6

Name the type of nuclear radiation that consists of positively-charged particles that are identical to helium nuclei.

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Answer

The type of nuclear radiation that consists of positively-charged particles identical to helium nuclei is called alpha radiation.

Step 7

Calculate the percentage by mass of sulfur in sulfur trioxide (SO₃).

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Answer

To calculate the percentage by mass of sulfur in sulfur trioxide (SO₃), we start by determining the molar mass:

Molar mass of S = 32.07 g/mol
Molar mass of O = 16.00 g/mol

Molar mass of SO₃ = 32.07 g/mol (S) + 3 × 16.00 g/mol (O) = 32.07 g/mol + 48.00 g/mol = 80.07 g/mol.

Now, the percentage of sulfur by mass is given by:

$\text{Percentage of S} = \left( \frac{32.07}{80.07} \right) \times 100 \approx 40.0\%$

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Questions answered

What is the shape of an ammonia (NH₃) molecule?

Is this reaction exothermic or endothermic? Explain your answer.

What does this test tell you about the type of bonding in the liquid?

Why is chlorine added to the water in swimming pools?

Which of the following particles carry the electric current through a solution during electrolysis?

Name the type of nuclear radiation that consists of positively-charged particles that are identical to helium nuclei.

Calculate the percentage by mass of sulfur in sulfur trioxide (SO₃).

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