1.)

a.)
i.) Define the term electronegativity.
Electronegativity is defined as the ability of an atom to attract electrons towards itself in a covalent bond.

ii.) Arrange the following elements in order of increasing electronegativity: chlorine, nitrogen, fluorine.
The order of increasing electronegativity is: nitrogen < chlorine < fluorine.

b.) An experiment was conducted to determine the enthalpy change of a reaction. The following data was collected:

• Initial temperature: 25°C
• Final temperature: 30°C

Mass of solution: 100 g
Heat capacity of solution: 4.18 J/g·°C
Calculate the enthalpy change of the reaction.

The enthalpy change of the reaction can be calculated using the formula:
ΔH = q/m, where q is the heat absorbed by the solution, and m is the mass of the solution.
The heat absorbed by the solution can be calculated using the formula: q = mcΔT, where c is the heat capacity of the solution, and ΔT is the change in temperature.

Substituting the values given, we get:
q = (100 g) x (4.18 J/g·°C) x (30°C – 25°C) = 2090 J
ΔH = q/m = 2090 J/0.1 kg = 20,900 J/kg = 20.9 kJ/mol

2.)

a.)
i.) Define the term acid dissociation constant (K_a)
Acid dissociation constant (K_a) is a measure of the strength of an acid in solution. It is defined as the ratio of the concentrations of the products to the concentration of the acid, raised to the power of the number of acidic protons dissociated.

ii.) Write the expression for the Ka of acetic acid (CH3COOH)
The expression for the Ka of acetic acid (CH₃COOH) is:
Ka = [H⁺][CH₃COO-]/[CH₃COOH]

iii.) Calculate the pH of a 0.1 M solution of acetic acid, given that Ka = 1.8 × 10^-5.
To calculate the pH of a 0.1 M solution of acetic acid, we first need to calculate the concentration of H+ ions using the Ka value:
Ka = [H⁺][CH₃COO^–]/[CH₃COOH]
1.8 x 10^-5 = [H⁺][0.1]/[0.1]
[H⁺] = 1.34 x 10^-3 M
Now, we can calculate the pH using the formula:
pH = -log[H⁺]
pH = -log(1.34 x 10^-3)
pH = 2.87
Therefore, the pH of a 0.1 M solution of acetic acid is 2.87.

b.) The following reaction takes place in a closed system:
N₂(g) + 3H₂(g) ⇌ 2NH₃(g)

i.) What effect does increasing the pressure have on the position of equilibrium? Explain your answer.
Increasing the pressure would shift the position of equilibrium towards the side with fewer gas molecules. In this case, the position of equilibrium would shift towards the side with fewer moles of gas, which is the right-hand side (the side with NH₃). Therefore, increasing the pressure would increase the concentration of NH₃.

ii.) What effect does increasing the concentration of nitrogen have on the position of equilibrium? Explain your answer.
Increasing the concentration of nitrogen would shift the position of equilibrium towards the side with fewer moles of gas, which is the left-hand side (the side with N₂ and H₂). Therefore, increasing the concentration of nitrogen would decrease the concentration of NH₃.

3.) Urea is used as a fertilizer. It is secreted by mammals.

a.) The structural formula for urea is shown below. State the electron domain geometry and molecular geometry for the Nitrogen and Carbon atoms.
Answer:
Nitrogen has a tetrahedral electron geometry structure and a trigonal pyramidal molecular geometry structure. Whereas, carbon has a trigonal planar electron geometry structure and a trigonal planar molecular geometry structure.

b.) Urea can be made from a direct combination of ammonia and carbon dioxide gasses.
2NH₃ (g) + CO₂ (g) ⇌ (H₂N)₂CO (g) + H₂O (g) Enthalpy < 0
Outline what happens to the equilibrium constant when the temperature is increased
Answer:
Since the reaction is exothermic (enthalpy is lesser than 0), the reverse reaction will be favored and the equilibrium constant will decrease.

c.) Urea combustion produces water, carbon dioxide and nitrogen. Write a balanced equation for the reaction with the state symbols.
Answer:
2(H₂N)₂CO (s) + 3O₂ (g) → 4H₂O (l) + 2CO₂ (g) + 2N₂ (g)
Balanced equation means the total number of moles are equal on both sides. The number of moles on the LHS add up to 12 → [(2 x 2) + 2 + (3 x 2)] = 12.) For the RHS, it also adds up to 12 → [4 + (2 x 2) + (2 x 2)]