The ideal gas law, R, can be experimentally determined. Use the data provided below from the reaction of potassium chlorate decomposing to form oxygen gas and potassium chloride to experimentally determine the value of R in units of L•atm/mol•K. 2KClO3 (s) → 2KCl (s) + 3O2 (g) The evolved oxygen is collected over water. The relevant data from the experiment is summarized below. Mass of KClO3 used 0.0665 g Initial volume reading 46.0 mL Final volume reading 64.2 mL Temperature 22.0°C Total pressure 772.0 mm Hg A table of vapor pressures of water is also available: Temperature (°C) Vapor Pressure of Water (mm Hg) 21 18.7 22 19.8 23 21.1 24 22.4 25 23.8 How many moles of KClO3 were used in this experiment? How many moles of O2 gas were evolved in this experiment? What is the experimentally determined value of the ideal gas law constant, R, expressed in L•atm/mol•K?
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.
The
Use the data provided below from the reaction of potassium chlorate decomposing to form oxygen gas and potassium chloride to experimentally determine the value of R in units of L•atm/mol•K.
2KClO3 (s) → 2KCl (s) + 3O2 (g)
The evolved oxygen is collected over water. The relevant data from the experiment is summarized below.
| Mass of KClO3 used | 0.0665 g |
| Initial volume reading | 46.0 mL |
| Final volume reading | 64.2 mL |
| Temperature | 22.0°C |
| Total pressure | 772.0 mm Hg |
A table of vapor pressures of water is also available:
| Temperature (°C) | Vapor Pressure of Water (mm Hg) |
| 21 | 18.7 |
| 22 | 19.8 |
| 23 | 21.1 |
| 24 | 22.4 |
| 25 | 23.8 |
How many moles of KClO3 were used in this experiment?
How many moles of O2 gas were evolved in this experiment?
What is the experimentally determined value of the ideal gas law constant, R, expressed in L•atm/mol•K?
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