A spirit burner containing 5.0 g sample of propanol (C3H7OH) is used to heat up a beaker of water (0.65 L) from 25.0 celcius degree to 58.0 celcius degree. The standard enthalpy change of combustion of propanol is −2010 kJ mol−1. (Assume that the density and specific heat capacity of water are 1.0 g cm−3 and 4.2 J g−1 K−1 respectively.) (Molar mass of propanol: 60 g) (a) State ONE assumption in the experiment. (b) Calculate the actual mass of propanol used to heat the water. (c) Calculate the percentage purity of propanol in the sample.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
A spirit burner containing 5.0 g sample of propanol (C3H7OH) is used to heat up a beaker of water (0.65 L) from 25.0 celcius degree to 58.0 celcius degree. The standard enthalpy change of combustion of propanol is −2010 kJ mol−1. (Assume that the density and specific heat capacity of water are 1.0 g cm−3 and 4.2 J g−1 K−1 respectively.)
(Molar mass of propanol: 60 g)
(a) State ONE assumption in the experiment.
(b) Calculate the actual mass of propanol used to heat the water.
(c) Calculate the percentage purity of propanol in the sample.
Step by step
Solved in 6 steps