DP 1 exam practice

Electron configuration and ionic bonding

100

What is the electron configuration of Cu²⁺

1s²2s²2p⁶3s²3p⁶3d⁹

200

What is the electron configuration of Fe²⁺ (Z=26)

1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶

300

Which equation correctly represents the lattice enthalpy of potassium oxide?

 A. K2O(s) → 2K⁺ (g) + O^2– (g) 

B. K2O(s) → 2K(s) + ½O₂ (g) 

C. K2O(s) → K₂ ²⁺ (g) + O^2– (g) 

D. K2O(s) → 2K(g) + ½O₂ (g)

A

400

State and explain which of the following ionic compounds you expect to have the greatest lattice enthalpy value: NaCl, MgCl2 , Na2O or MgO.

MgO>Na2O>MgCl2>NaCl

More q/r ratio means more electrostatic attraction between the ions.

500

Explain why zinc is not a transition element

A transition element must have incomplete d orbital and Zn has it full.

Stoichiometry

100

What is the molar mass, in g mo^-1, of a compound if 0.200 mol of the compound has a mass of 13.2 g?

13.2g/0.2mol= 66g mol^-1

200

What volume of oxygen, in dm³ at STP, is needed when 5.8g of butane undergoes complete combustion?

2C₄H₁₀(g) + 13O₂(g) → 8CO₂ (g) + 10H₂0(l)

0.65mols of O2. P·V=nRT (or 22.7L=1mol)

so 101.325KPa·V=0.65mol·8.31·273.15K; 

V=14.56L of O2.

300

At what temperature would 2.10 moles of N₂ gas have a pressure of 1.25 atm and in a 25.0 L tank?

181K

400

How many moles of Kr are present in 57.6L at STP?

0.025

500

In aerobic respiration 32 grams of glucose reacts with 48 grams of oxygen. Which molecule is the limiting reactant and by how many grams? How many grams of carbon dioxide were produced?

Glucose is the limiting reactant by 12.6 grams. 47.52 grams of CO2 is produced

Lewis structure

100

Draw the Lewis structure of:

C₂H₅OC₂H₅

   H H     H H

H-C-C-O-C-C-H

    H H     H H

200

What is the molecular geometry of methanol (H3COH)? Deduce also the electron domain geometry of the O atom.

Tetrahedral. O: tetrahedral.

300

Explain why noble gases do not form ions

They have full e configuration. Very stable.

400

What is the bond order of CO₃^2-?

BOARD

500

Deduce the lewis structure, formal charges and ionic geometry of SO₄ ^2–

BOARD

Molecular geometry

100

What are the electron domain geometries around the carbon and both nitrogen atoms of (NH₂)₂CO?

C: trigonal planar

N: tetrahedral

200

What are the electron domain geometry and molecular geometry of H₂O and SO₂, respectively?

H2O: electron domain geometry-tetrahedral; molecular geometry-V-shape.

SO2: electron domain geometry-trigonal plainer; molecular geometry-V-shape.

300

The molecular masses of ICl and Br2 are very similar, while their boiling points are 97.4°C and 58.8°C, respectively. Explain this difference.

ICl is a polar molecule: intermolecular forces stronger: dipole-dipole

Br2 is a non-polar molecule: intermolecular forces weaker: LDF

400

Discuss why Methane, CH4 , ammonia, NH3 , and water, H2O have different bond angle if they are all V-shaped molecules.

Number of lone pairs of electrons on the central atom

500

State and explain which of the following species can form hydrogen bonds with water molecules: 

a. ammonia, NH3 

b. propane, CH3CH2CH3 

c. ethanoic acid, CH3COOH

A and C

Metallic bonding

100

What is the correct order of metallic bond strength from strongest to weakest?

Na, K, Rb, Cs

Na>K>Rb>Cs

200

How does ionic radius affect the electrical conduct of a metal?

More the ionic radius = more electrons attached = less free electrons = less electrical conduct

 

300

Why does the electrical conductivity of metals decrease with increasing temperature?

Tempertuare⬆, vibration of metal ion ⬆(⬆collision and kinetic energy, electrons will be less affected). This results in ⬆ in electrical resistance. Hence, ⬇in electrical conductivity.