IB Chemistry

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

Tags

NGSS.HS-PS1-3

NGSS.HS-PS2-4

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

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)

Tags

NGSS.HS-PS1-4

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

At 700 ºC, the equilibrium constant, K_c, for the reaction is 1.075 × 10⁸.

2H₂ (g) + S₂ (g) <- -> 2H₂S (g)

Which relationship is always correct for the equilibrium at this temperature?

• [H₂S]² < [H₂]² [S₂]

• S₂] = 2[H₂S]

• [H₂S] < [S₂]

• [H₂S]² > [H₂]²[S₂]

Which of the following will form a buffer solution if combined in appropriate molar ratios?

• HCl and NaCl

• NaOH and HCOONa

• NH₄Cl and HCl

• HCl and NH₃

What is the product of the reaction between pentan-2-one and sodium borohydride, NaBH₄?

• Pentan-1-ol

• Pentan-2-ol

• Pentanoic acid

• Pentanal

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)

Tags

NGSS.HS-PS1-4