1) How much heat will be released when 4.72g of carbon reacts with excess O2 according to the following equation? C + O2 → CO2 ∆H = -393.5 kJ 2) What mass of iron must react to produce 3600 kJ energy? 3) Determine the specific heat capacity of 250.0g of an unknown metal. When the metal absorbs 18.1 kJ of heat, its temperature increases from 23.1°C to 103.5°C
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.
1) How much heat will be released when 4.72g of carbon reacts with excess O2 according to the following equation? C + O2 → CO2 ∆H = -393.5 kJ
2) What mass of iron must react to produce 3600 kJ energy?
3) Determine the specific heat capacity of 250.0g of an unknown metal. When the metal absorbs 18.1 kJ of heat, its temperature increases from 23.1°C to 103.5°C
4) Determine the heat associated with a decrease in the temperature of 375g of water from 31.5°C to 24.6°C. The specific heat capacity of water is 4.18 J/g°C.
5) Find the ∆H for the reaction below, given the following reactions and subsequent ∆H values:
H2SO4 (l) → SO3 (g) + H2O (g)
H2S (g) + 2O2 (g) → H2SO4 (l) ∆H = -235.5 kJ
H2S (g) + 2O2 (g) → SO3 (g) + H2O (l) ∆H = -207 kJ
H20 (l) → H2O (g) ∆H = 44 kJ
6) Calculate ∆H for the reaction 4NH3 (g) + 5O2 (g) → 4NO (g) + 6H2O (g), from the following data.
N2 (g) + O2 (g) → 2NO (g) ∆H = -180.5 kJ
N2 (g) + 3H2 (g) → 2 NH3 (g) ∆H = -91.8 kJ
2H2 (g) + O2 (g) → 2H2O (g) ∆H = -483.6 kJ
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