IB Chemistry HL Exam Practice

Which statements are correct for ionic compounds?

I. Lattice energy increases as ionic radii increase.

II. Within the same group, the melting point of salts tends to decrease as the radius of the cation increases.

III. Solubility in water depends on the relative magnitude of the lattice energy compared to the hydration energy.

• I and II only

• I and III only

• II and III only

• II and III only

What is the standard enthalpy of formation, in kJ mol^–1, of IF (g)?

IF₇ (g) + I₂ (s) → IF₅ (g) + 2IF (g) ΔH = –89 kJ

ΔH_f (IF₇) = –941 kJ mol^–1

ΔH_f (IF₅) = –840 kJ mol^–1

• –190

• –95

• +6

• +95

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Which equation represents the lattice enthalpy of magnesium sulfide?

• MgS (s) → Mg (g) + S (g)

• MgS (s) → Mg⁺ (g) + S^– (g)

• MgS (s) → Mg²⁺ (g) + S^2– (g)

• MgS (s) → Mg (s) + S (s)

The rate expression for the reaction X (g) + 2Y (g) → 3Z (g) is

rate = k[X]⁰ [Y]²

By which factor will the rate of reaction increase when the concentrations of X and Y are both increased by a factor of 3?

• 6

• 9

• 18

• 27

Tags

NGSS.HS-PS1-5

Which combination describes the PH₄⁺ ion?

• Tetrahedral; sp³ hybridization

• Square Planar, sp³ hybridization

• Tetrahedral, sp² hybridization

• Square Planar, sp² hybridization

Which species have resonance structures?

I. Ozone, O₃

II. Carbon dioxide, CO₂

III. Benzene, C₆H₆

• I and II only

• I and III only

• II and III only

• I, II and III

Which equation represents enthalpy of hydration?

• Na(g) → Na⁺(aq) + e⁻

• Na⁺(g) → Na⁺(aq)

• NaCl(s) → Na⁺(g) + Cl⁻(g)

• NaCl(s) → Na⁺(aq) + Cl⁻(aq)

Which combination of ΔH ^θ and ΔS ^θ will result in a non-spontaneous reaction at all temperatures?

• ΔH ^θ - Positive; ΔS ^θ - Negative

• ΔH ^θ - Negative; ΔS ^θ - Positive

• ΔH ^θ - Positive; ΔS ^θ - Positive

• ΔH ^θ - Negative; ΔS ^θ - Negative

What are the units for the rate constant, k, in the expression?

Rate = k [X]²[Y]

• mol² dm⁻⁶ s⁻¹

• mol⁻¹ dm³ s⁻¹

• mol dm⁻³ s⁻¹

• mol⁻² dm⁶ s⁻¹

Tags

NGSS.HS-PS1-5

Which molecule is chiral?

• 2-chlorobutane

• 2,2-dichloropentane

• Propan-2-amine

• 4-hydroxybutanoic acid