Match the reaction (under standard conditions) with the temperature range at whi
ID: 987059 • Letter: M
Question
Match the reaction (under standard conditions) with the temperature range at which it is expected to be spontaneous.
H2 (g) + Br2 (l) --> 2 HBr (g)
the heat of formation for HBr is -36 kJ/mol
H2 (g) + I2 (s) --> 2 HI (g)
the heat of formation for HI is +26 kJ/mol
N2 (g) + 2 O2 (g) --> 2 NO2 (g)
the heat of formation for NO2 is +34 kJ/mol
N2 (g) + 3 H2 (g) --> 2 NH3 (g)
the heat of formation for NH3 is -46 kJ/mol
spontaneous at high temperatures
spontaneous at low temperatures
nonspontaneous at all temperatures
spontaneous at all temperatures
H2 (g) + Br2 (l) --> 2 HBr (g)
the heat of formation for HBr is -36 kJ/mol
H2 (g) + I2 (s) --> 2 HI (g)
the heat of formation for HI is +26 kJ/mol
N2 (g) + 2 O2 (g) --> 2 NO2 (g)
the heat of formation for NO2 is +34 kJ/mol
N2 (g) + 3 H2 (g) --> 2 NH3 (g)
the heat of formation for NH3 is -46 kJ/mol
A.spontaneous at high temperatures
B.spontaneous at low temperatures
C.nonspontaneous at all temperatures
D.spontaneous at all temperatures
Explanation / Answer
For HBr, as entropy is positive and enthalpy is negative, the reaction will be spontaneous at any temperature.
For HI, as entropy is positive and enthalpy is positive, the reaction will be spontaneous at high temperatures
For NO2, as entropy is negative and enthalpy is positive, the reaction will be nonspontaneous at all temperatures.
For NH3, as entropy is negative and enthalpy is negative, the reaction will be spontaneous at low temperatures.