Enthalpy change ;(ΔH) Enthalpy is the quantity of heat energy
absorbed or released
in a reaction .
2. If the reaction absorbs heat , it is called endothermic
reaction whose (ΔH) is
represented as positive number.
If the reaction releases heat, it is called exothermic reaction
whose (ΔH) is
represented as negative number.
1-Define enthalpy change (ΔH). 2-What is the significance of negative and positive ΔH?
What combinations of positive or negative ΔH and positive or negative ΔS can indicate a spontaneous reaction? Choose one or more:–ΔH, –ΔS+ΔH, –ΔS–ΔH, +ΔS+ΔH, +ΔS
The sign of ΔG will be negative when ΔS is positive and ΔH is positive ΔS is negative and ΔH is positive ΔS is positive and ΔH is negtive ΔS is negative and ΔH is negative
The enthalpy change, ΔH, for a reaction at constant pressure is defined as: ΔH = ΔE + PΔV. For which of the following reactions will ΔH be approximately equal to ΔE? Select all that apply. Group of answer choices 2 NO2(g) -> N2(g) + 2 O2(g) Ca(OH)2(aq) + H2SO4(aq) -> 2 H2O(l) + CaSO4(s) C(s) + O2(g) -> CO2(g) None of the above
Define: mean, median, mode, variability, correlation, positive correlation, negative correlation, statistical significance
When 1.00 mole of NH4NO3 dissolves in water, the enthalpy change is ΔH = + 25.7 kJ. What is the enthalpy change if 17.5 grams of NH4NO3 are dissolved in water?
Use the enthalpies for the given reactions to compute the standard enthalpy change (ΔH°) for the reaction: 6 C (s) + 7 H2(g) → C6H14 (l) ΔHrxn = ? C6H14 (l)+19/2O2 (g)→6CO2(g)+ 7H2O(g). ΔH=–3505.8kJ C(s) + O2 (g) → CO2(g) ΔH=–393.5kJ H2(g) + 1/2 O2(g) → H2O(g). ΔH = – 242.0 kJ
If the reaction A + 2B ⇌ 2C has a change in enthalpy of ΔH=-8.71kJ/mol and a change in entropy of ΔS= -5.88J/mol*K and the reaction of B + D ⇌ C has a change in enthalpy of ΔH=-3.45kJ/mol and a change in entropy of ΔS= 11J/mol*K, is the reaction of A ⇌ 2D spontaneous at room temperature? Yes, ΔG > 0 Yes, ΔG < 0 No, ΔG > 0 No, ΔG < 0
What is the measured enthalpy change (ΔH) of a 2.5 gram sample of NaCl is placed in 100.0 mL of water in a coffee cup calorimeter (s=4.18 J/g°C) when the temperature changes from 20.6ºC to 21.2ºC?
The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of one mole of substance from its constituent elements in their standard states. Thus, elements in their standard states have ΔH∘f=0. Heat of formation values can be used to calculate the enthalpy change of any reaction. Consider, for example, the reaction 2NO(g)+O2(g)⇌2NO2(g) with heat of formation values given by the following table: Substance ΔH∘f (kJ/mol) NO(g) 90.2 O2(g) 0 NO2(g) 33.2 Then the standard heat...
Calculate the change in enthalpy (ΔH) for the heat of formation of ethane, C2H6, using Hess' Law and the following reactions:a) 2C(S) + 2O2(g) → 2CO2(g), ΔH = -188 kcalb) C2H6(g) + (7/2)O2(g) → 2CO2(g) + 3H2O(l), ΔH = -373 kcalc) H2(g) + (1/2)O2(g) → H2O(l), ΔH = -68.3 kcal