IB Chemistry Standard Level

1. What is the molar mass, in g mol−1, of a compound if 0.200 mol of the compound has a mass of 13.2 g? A. 66.0 B. 66 C. 26.4 D. 26

2. What is the number of carbon atoms in 12 g of ethanoic acid CH3COOH, Mr = 60? A. 0.20 B. 2.0 C. 1.2 × 1023 D. 2.4 × 1023

3. Which of these molecular formulae are also empirical formulae? I. C2H6O II. C2H4O2 III. C5H12 A. I and II only B. I and III only C. II and III only D. I, II and III

Turn over 4. Which volume of ethane gas, in cm3, will produce 40 cm3 of carbon dioxide gas when mixed with 140 cm3 of oxygen gas, assuming the reaction goes to completion? 2C2H6 (g) + 7O2 (g) → 4CO2 (g) + 6H2O (g) A. 10 B. 20 C. 40 D. 80

5. What is the relative atomic mass, Ar, of an element with this mass spectrum? Mass/charge Percent abundance 25 24 0 20 40 60 80 100 26 A. 24.0 B. 24.3 C. 24.9 D. 25.0

6. What is the maximum number of electrons that can occupy the 4th main energy level in an atom? A. 8 B. 14 C. 18 D. 32

7. Which of the following shows a general increase across period 3 from Na to Cl? A. Ionic radius B. Atomic radius C. Ionization energy D. Melting point

8. Which oxide will dissolve in water to give the solution with the lowest pH? A. P4O10 B. SiO2 C. Al2O3 D. MgO

9. Which formula is correct? A. NH4PO4 B. (NH4)2PO4 C. (NH4)3PO4 D. (NH4)3(PO4)2

10. Which molecule is most polar? A. CHF3 B. CF4 C. CClF3 D. CCl4

Turn over 11. Which combination correctly describes the geometry of the carbonate ion, CO3 2−? Electron domain geometry around C Molecular geometry around C A. Trigonal planar Trigonal pyramidal B. Tetrahedral Trigonal planar C. Trigonal planar Trigonal planar D. Tetrahedral Trigonal pyramidal

12. Which series shows the correct order of metallic bond strength from strongest to weakest? A. Na > K > Rb > Mg B. Mg > Rb > K > Na C. Rb > K > Na > Mg D. Mg > Na > K > Rb

13. Which equation shows the enthalpy of formation, ∆Hf, of ethanol? A. 2C (s) + 3H2 (g) + 1 2 O2 (g) → C2H5OH (g) B. 4C (s) + 6H2 (g) + O2 (g) → 2C2H5OH (g) C. 2C (s) + 3H2 (g) + 1 2 O2 (g) → C2H5OH (l) D. 4C (s) + 6H2 (g) + O2 (g) → 2C2H5OH (l)

14. Which combination will give you the enthalpy change for the hydrogenation of ethene to ethane, ∆H3? 2C (s) + 3H2 (g) C2H4 (g) + H2 (g) C2H6 (g) + 2O2 (g) + 2O2 (g) 2CO2 (g) + 3H2 (g) ∆H2 ∆H3 ∆H4 ∆H1 A. −∆H2 + ∆H1 − ∆H4 B. ∆H2 − ∆H1 + ∆H4 C. ∆H2 + ∆H1 − ∆H4 D. −∆H2 − ∆H1 + ∆H4

15. What is the H−H bond enthalpy, in kJ mol−1, in the H2 molecule? 2H2 (g) + O2 (g) → 2H2O (g) ∆Hf (H2O) = x kJ mol−1 Bond Bond enthalpy / kJ mol−1 O=O y O–H z A. x − y + 4z B. 1 2 (x − y + 4z) C. x − y + 2z D. 1 2 (x − y + 2z)

Turn over 16. Which apparatus can be used to monitor the rate of this reaction? CH3COCH3 (aq) + I2 (aq) → CH3COCH2I (aq) + H+ (aq) + I− (aq) I. A pH meter II. A gas syringe III. A colorimeter A. I and II only B. I and III only C. II and III only D. I, II and III

17. Which arrow shows the activation energy of the uncatalysed forward reaction for this equilibrium? 2SO2 (g) + O2 (g)  2SO3 (g) ∆H = −196 kJ mol−1 Enthalpy Reaction coordinate 2SO2 (g) + O2 (g) 2SO3 (g) A B C D

18. What is correct when temperature increases in this reaction at equilibrium? 2NOCl (g)  2NO (g) + Cl2 (g) ∆H Ö = +75.5 kJ Position of equilibrium Equilibrium constant, Kc A. Shifts left Unchanged B. Shifts left Decreases C. Shifts right Unchanged D. Shifts right Increases

19. Which substance will not produce copper(II) chloride when added to dilute hydrochloric acid? A. Cu (s) B. Cu(OH)2 (s) C. CuCO3 (s) D. CuO (s)

20. Which of these acids has the weakest conjugate base? A. HCl B. CH3COOH C. NH4Cl D. C6H5COOH