Concept explainers
Nitromethane, CH3NO2, can be used as a fuel. When the liquid is burned, the (unbalanced) reaction is mainly
CH3NO2(l) + O2(g) → CO2(g) + N2(g) + H2O(g)
- a. The standard enthalpy change of reaction (ΔH°van ) for the balanced reaction (with lowest whole-number coefficients) is −1288.5 kJ. Calculate ΔHf0 for nitromethane.
- b. A 15.0-L flask containing a sample of nitromethane is filled with O2 and the flask is heated to 100.°C. At this temperature, and after the reaction is complete, the total pressure of all the gases inside the flask is 950. torr. If the mole fraction of nitrogen (χnitrogen) is 0.134 after the reaction is complete, what mass of nitrogen was produced?
(a)
Interpretation:
Considering the given equation the enthalpy of formation for nitromethane and the mass of nitrogen produced when given volume of sample is stored under
Concept Introduction:
Enthalpy change: It is defined as the amount of heat released or absorbed by the chemical reaction at constant pressure conditions. The standard enthalpy of the reaction is equal to the subtraction of total enthalpy for formation product with the total enthalpy for formation of the reactants which is given as
Ideal Gas equation: It is the equation which equals the pressure and volume product of one mole of gas to the temperature and gas constant which is
Enthalpy change of combustion: It is the heat energy change involved when one mole of substance gets burned in pressure of oxygen under standard conditions.
Standard enthalpy of formation: It is the heat required when one mole of substance formed from its pure elements in standard state.
Limiting Reagent: A reactant is considered as limiting reagent when it limits the product formation that depend on the amount of that reactant.
Answer to Problem 134IP
The standard enthalpy of formation
Explanation of Solution
To determine: The
Given,
Analyse the given equation and balance it.
The unbalanced equation is
Therefore, the balanced equation where the number of moles of product and the reactant on both side of the equation should be equal is depicted as follows
Now, the enthalpy of formation for the given product is calculated as follows,
The enthalpy of formation for the given product nitromethane was determined.
(b)
Interpretation:
Considering the given equation the enthalpy of formation for nitromethane and the mass of nitrogen produced when given volume of sample is stored under
Concept Introduction:
Enthalpy change: It is defined as the amount of heat released or absorbed by the chemical reaction at constant pressure conditions. The standard enthalpy of the reaction is equal to the subtraction of total enthalpy for formation product with the total enthalpy for formation of the reactants which is given as
Ideal Gas equation: It is the equation which equals the pressure and volume product of one mole of gas to the temperature and gas constant which is
Enthalpy change of combustion: It is the heat energy change involved when one mole of substance gets burned in pressure of oxygen under standard conditions.
Standard enthalpy of formation: It is the heat required when one mole of substance formed from its pure elements in standard state.
Limiting Reagent: A reactant is considered as limiting reagent when it limits the product formation that depend on the amount of that reactant.
Answer to Problem 134IP
The mass of nitrogen produced from the given reaction under given conditions is
Explanation of Solution
Given,
The total pressure of gas is
Given mole fraction of nitrogen is
Analysing the given reaction shows us that 4 moles of
Therefore, the mass of nitrogen produced during the given reaction under given conditions is
The mass of nitrogen produced during the given reaction was determined.
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Chapter 6 Solutions
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