4. a) The enthalpy change of combustion of hexane was measured using
a calorimeter containing 200 cm3 of water; 0.5g of hexane (C6H14) was burnt.
The temperature of the water increased by 28.50K.
Calculate the enthalpy change of combustion of hexane.
(c = 4.184 kJ kg-1K-2). Give your answer in kJmol-1.
b) Suggest why this experimental value is less than the standard enthalpy
change of combustion of hexane found in a data book.

Astable electron arrangement for an atom is one that does not easily change. how is this arrangement arrived at? a. valence electrons are transferred or shared to create a full outer shell of electrons. b. valence electrons are discarded into space to create a full outer shell of electrons. c. protons (positive charge) pair with valence electrons (negative charge) to create a strong bond. d. outer shells with valence electrons are transferred or shared.