Chemistry_2014_STPM term 2_Objectives

Which enthalpy changes have negative values?

• p , t , w

• p , v , w

• q , s , u

• t , v , w

The thermochemical equation for the neutralisation reaction of sulphuric acid by aqueous solution of potassium hydroxide is given below.

2 KOH (aq) + H₂SO₄ (aq) → K₂SO₄ (aq) + 2 H₂O (l) ΔH° = −114 kJ

What is the standard enthalpy of neutralisation, in kJ mol^-1, for the reaction between nitric acid with an aqueous solution of sodium hydroxide?

• − 28.5

• − 57

• − 114

• − 228

Which compound has the lowest lattice energy?

• CaCl₂

• CsCl

• K₂O

• MgCl₂

The half - cell equation and the standard reduction potential for X and Y are shown below.

Half − cell reaction E°∕V

X²⁺ (aq) + 2e^- ⇌ X (s) + 0.34

Y⁺ (aq) + e^- ⇌ Y (s) + 0.80

What is the e. m. f of the cell constructed from the two half cells?

• − 1 .14 V

• − 0 .46 V

• + 0 .46 V

• + 1 .26 V

Standard reduction potential for X is –0.76 V. Which statement is not true of the above cell?

• Hydrogen is a stronger reducing agent than X.

• The cell diagram is Pt (s) | H₂ (g) | H⁺ (aq) ‖ Xⁿ⁺ (aq) | X (s)

• The voltmeter reading at standard condition is 0.76V.

• The equation for the overall cell reaction is 2X (s) + 2nH⁺ (aq) → 2Xⁿ⁺ (aq) + nH2 (g)

Which statement explains why graphite powder is spread onto material first in plastic electroplating process?

• Graphite is an electric conductor.

• Plastic becomes more resistant to heat.

• Plastic electroplating process is accelerated.

• Graphite can form chemical bond with plastic.

Which element has an oxide which dissolves in water to form an acidic solution?

• Al

• Na

• P

• Si

The factor that explains the variation observed above is

• anionic size

• lattice energy

• polarisability of anion

• polarising power of cation

Zeolite is a type of aluminosilicate with an empirical formula NaAiSi₂O₆. H₂O. The following are use of zeolite except as a/an

• catalyst

• superconductor

• dehydration agent

• ion exchange resin