Aggiornamento
Istantanee iPhone
Istantanee iPad
Descrizione
Thermochemistry helps in evaluation of enthalpy or heat release/absorption of a system undergoing numerous temperature changes and phase transitions. The calculations take advantage of known values of heat capacity at constant pressure (Cp) and molar or per gram enthalpy of phase transition. Amount of compound can be defined in grams or moles, in a way that Cp and enthalpy units would match.
App provides enthalpy values for each step. Negative enthalpy points to exothermic process – heat release, while positive one to endothermic - heat absorption. °C and K are interchangeable.
Calorimetry section provides means for evaluation of the heat capacity of calorimeter and for finding equilibrium temperature of mixed system. Forward arrow button sets the final temperature of the mixture. Backward arrow button sets missing temperature or heat capacity of one of the components. Enthalpy values show heat flow for each component.
Example of problems solved by application (screenshots):
Problem 1: Calculate the amount of energy required to change 100.0 g of ice at -15.0 °C to steam at 125.0 °C. Known values:
Heat of melting = 334.16 J g¯1
Heat of vaporization = 2259 J g¯1
specific heat capacity for solid water (ice) = 2.06 J g¯1 K¯1
specific heat capacity for liquid water = 4.184 J g¯1 K¯1
specific heat capacity for gaseous water (steam) = 2.02 J g¯1K¯1
Solution:
1) Heating of 100.0 g of ice from -15.0°C to 0.0°C:
(100.0 g) (15.0 K) (2.06 J g¯1 K¯1) = 3090 J
2) Melting of 100.0 g of ice:
(100.0 g) (334.16 J g¯1) = 33416 J
3) Heating of 100.0 g of liquid water from zero to 100.0 Celsius:
(100.0 g) (100.0 K) (4.184 J g¯1 K¯1) = 41840 J
4) Evaporations of 100.0 g of liquid:
(100.0 g) (2259 J g¯1) = 225900 J
5) Heating of 100.0 g of steam from 100.0 to 125.0 Celsius:
(100.0 g) (25.0 K) (2.02 J g¯1 K¯1) = 5050 J
6) Summation of the results:
3090 + 33416 + 41840 + 225900 + 5050 = 309.3 kJ
Problem 2: Determine the heat capacity of a coffee-cup calorimeter. During calibration 100.0 g of water at 58.5 °C has been added to 100.0 g of water, already in the calorimeter, at 22.8 °C. Calculate the heat capacity of the calorimeter in J/°C, if final temperature of the water is 39.7 °C. (Specific heat of water is 4.184 J/g °C.)
Solution:
1) Heat given up by warm water:
q = (100.0 g) (18.8 °C) (4.184 J/g °C) = 7865.92 J
2) Heat absorbed by water in the calorimeter:
q = (100.0 g) (16.9 °C) (4.184 J/g °C) = 7070.96 J
3) The difference was absorbed by the calorimeter:
7865.92 - 7070.96 = 794.96 J
4) Calorimeter constant:
794.96 J / 16.9 °C = 47.0 J/°C
Problem 3: Determine the final temperature when 10.0 g of aluminum at 130.0 °C mixes with 200.0 grams of water at 25.0 °C.
Please note the starting temperature of the metal is above the boiling point of water. In reality, the sample may vaporize a tiny amount of water, but we will assume it does not for the purposes of the calculation.
Solution:
1) The colder water will warm up and the warmer metal will cool down. The whole mixture will equilibrate up at the same temperature. The energy which "flowed" out of the warmer metal equals the energy which "flowed" into the colder water:
Qaluminum = Qwater
(10) (130 - x) (0.901) = (200.0 )(x - 25) (4.18)
117.13 - 0.901x = 83.6x - 2090
x = 26.12 °C.
Important! Water didn’t cross temperature of phase transition – vaporization; otherwise calculation would be more complex.
Calculation of reaction standard Gibbs free energy:
For the general reaction aA + bB -> cC + dD
ΔG°rxn = cΔGf°(C) + dΔGf°(D) - aΔGf°(A) - bΔGf°(B)
Example: Calculate the Gibbs free energy for the following reaction at 25 °C.
Cu (s) + H2O (g) -> CuO (s) + H2 (g)
ΔG°rxn = ΔGf°(CuO (s)) – ΔGf°(H2O (g)) = (–129.7 kJ/mol) – (–228.6 kJ/mol)
= 98.9 kJ/mol
ΔGf° = 0; for elements in their standard state by definition.
At equilibrium, ΔG = 0!
Important points
Application uses dot as a decimal separator.
Special attention should be paid for units’ consistency.
Novità nella versione 4.1
Compatibility update.
Rivenditore
Nome
Roman Volinsky
Informazioni
Sviluppatore
Categorie
Versione
4.1
Dimensione
0,8 MB
Game Center
No
VPP Device Licensing
Sì
Classifica
Classificazione: 4+
Compatibilità
iOS 17.0 o successivo
Dispositivi
iPhone 5s, iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPhone XR, iPhone XS, iPhone XS Max, iPhone 11, iPhone 11 Pro, iPhone 11 Pro Max, iPhone SE (2a generazione), iPhone 12, iPhone 12 Pro, iPhone 12 Pro Max, iPhone 12 mini, iPhone 13, iPhone 13 Pro, iPhone 13 Pro Max, iPhone 13 mini, iPhone SE (3a generazione), iPhone 14, iPhone 14 Plus, iPhone 14 Pro, iPhone 14 Pro Max, iPhone 15, iPhone 15 Plus, iPhone 15 Pro, iPhone 15 Pro Max, iPhone 16, iPhone 16Plus, iPhone 16Pro, iPhone 16ProMax, iPad (5ª generazione) Wi-Fi, iPad (5ª generazione) Wi-Fi + Cellular, iPad (6a generazione) Wi-Fi, iPad (6a generazione) Wi-Fi + Cellular, iPad Pro, iPad Pro (Cellular), iPad Pro (9,7 pollici), iPad Pro (9,7 pollici) (Cellular), iPad Pro da 12,9 pollici (2a generazione), iPad Pro da 12,9 pollici (2a generazione) Wi-Fi + Cellular, iPad Pro da 10,5 pollici, iPad Pro da 10,5 pollici Wi-Fi + Cellular, iPad Pro da 11 pollici, iPad Pro da 11 pollici Wi-Fi + Cellular, iPad Pro da 12,9 pollici (3a generazione), iPad Pro da 12,9 pollici (3a generazione) Wi-Fi + Cellular, iPad Air, iPad Air (Cellular), iPad Air 2, iPad Air 2 (Cellular), iPad Air (terza generazione), iPad Air (terza generazione) Wi-Fi + Cellular, iPad mini Retina, iPad mini Retina (Cellular), iPad mini 3, iPad mini 3 (Cellular), iPad mini 4, iPad mini 4 (Cellular), iPad mini (5ª generazione), iPad mini (5ª generazione) Wi-Fi + Cellular, iPad (7ª generazione) Wi-Fi + Cellular, iPad Pro da 11 pollici (2a generazione), iPad Pro da 11 pollici (2a generazione) Wi-Fi + Cellular, iPad Pro da 12,9 pollici (4a generazione), iPad Pro da 12,9 pollici (4a generazione) Wi-Fi + Cellular, iPad Air (4ª generazione) (Wi-Fi), iPad Air (4ª generazione) (Wi-Fi + Cellular), iPad (8ª generazione) Wi-Fi, iPad (8ª generazione) Wi-Fi + Cellular, iPad Pro da 11 pollici (3a generazione), iPad Pro da 11 pollici (3a generazione) Wi-Fi + Cellular, iPad Pro da 12,9 pollici (5ª generazione), iPad Pro da 12,9 pollici (5ª generazione) Wi-Fi + Cellular, iPad (9ª generazione), iPad (9ª generazione) Wi-Fi + Cellular, iPad mini (6ª generazione), iPad mini (6ª generazione) Wi-Fi + Cellular, iPad Air (5a generazione), iPad Air (5a generazione) Wi-Fi + Cellular, iPad Pro da 11 pollici (4a generazione), iPad Pro da 11 pollici (4a generazione) Wi-Fi + Cellular, iPad Pro da 12,9 pollici (6a generazione), iPad Pro da 12,9 pollici (6a generazione) Wi-Fi + Cellular, iPad (10a generazione), iPad (10a generazione) Wi-Fi + Cellular, iPad Air da 11 pollici (M2) Wi-Fi, iPad Air da 13 pollici (M2) Wi-Fi, iPad Air da 13 pollici (M2) Wi-Fi + Cellular, iPad Pro da 11 pollici (M4) Wi-Fi, iPad Pro da 11 pollici (M4) Wi-Fi + Cellular, iPad Pro da 13 pollici (M4) Wi-Fi, iPad Pro da 13 pollici (M4) Wi-Fi + Cellular, iPad MiniA17Pro, iPad MiniA17ProCellular, iPod touch (sesta generazione), iPod touch (7ª generazione)
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