Question

The combustion of titanium with oxygen produces titanium dioxide: Ti (s) + O2(g) → TiO2 (s) When 2.060 g of titanium is combusted in a bomb calorimeter, the temperature of the calorimeter increases from 25.00 °C to 91.60 °C. In a separate experiment, the heat capacity of the calorimeter is measured to be 9.84 kJ/K. The heat of reaction for the combustion of a mole of Ti in this calorimeter is ________ kJ/mol.

Answer 1

Ti(s) + O₂(g) TiO₂(s)

It looks complicated, but its actually just trying to throw you off using Kelvin degrees. Yet each increase in kelvin degree is exactly the same as an increase in a Celcius degree.

Thus, the increase from 25C to 91.60 °C is 66.60 °C

If each degree increase requires = 9.84 kJ

The total energy increase = (66.6 x 9.84) kJ = 655.344 kJ

This is for 2.060 grams of Titanium

You need to find the kJ increase per mole.

Seeing that titanium has an atomic mass of 47.9,

So, moles of 2.060 g 0.721grams of Titanium is = 2.060 g / 47.9 = approximately 0.043 moles

Thus

Per 0.043 moles, the kJ increase is 655.344 kJ

1 mole, the increase is 655.344 kJ / 0.043 = 15240.56 kJ per mol

= 1.52 x 10⁴ kJ per mol

Watch out, though! This is energy given OUT, an exothermic reaction, therefore the heat of combustion is negative, ie

-1.52 x 10⁴kJ per mol