Heat
The standard unit for measuring heat
What is a joule (J)
Which equation would you use during a phase change?
Q=MCΔT
The units for change in Enthalpy.
What is kJmol-1?
What units are specific heat measured in?
What is J/g°C or cal/g°C
Breaking Bonds is a ___________ process and Making Bonds is a _______ process.
(1)Endothermic, (2) Exothermic
Fuel + O2 → CO2 + H2O
What is combustion
How much energy would it take to increase the heat of 72.0 g of liquid water by 20.0°C? (the specific heat of liquid water is 1.0 c/g°C)
What is 1440 cal
Use the following information to calculate the enthalpy change for the process H2O (g) → H2O (l)
2 H2 (g) + O2 (g) → 2 H2O (l) ΔH = -572 kJ mol-1
2 H2 (g) + O2 (g) → 2 H2O (g) ΔH = -484 kJ mol-1
-44 kJ mol-1
How much heat is necessary to change 10.0 g of water from 20°C to 75°C? (specific heat of water 1.0 c/g °C/ 4.179 J/g °C )
What is 550 cal or 2298.45 J
What is average bond enthalpy?
the energy needed to break one mole of bonds in gaseous molecules under standard conditions averaged over similar compounds.
What are the mathematical symbols in the equation: q = mCΔT?
q = heat m = mass (in grams) C = specific heat ΔT = change in temperature (in Celsius)
What is the general expression for the ∆H reaction of any reaction?
H (reaction) = Hf(products) - Hf(reactants)
A student added 5.350 g of ammonium chloride to 100.00 cm3 of water. The initial temperature of the water was 25.55 °C but it decreased to 21.79 °C. Calculate the enthalpy change that would occur when 1 mol of the solute is added to 1.000 dm3 of water.
+16.5 kJ mol–1
How much heat (in Joules) is necessary to change 20.0 g of water from 50°C to 75°C? (specific heat of water 4.179 J/g °C )
What is 2089.5 J
Use the bond enthalpies below to calculate ∆H ⊖ for the reaction: 2H2(g) + O2(g) → 2H2O(g)
O=O, +498 KJ/mol
H-H, +436 KJ/mol
O-H, +464 KJ/mol
–486 kJ
List the two type of chemical processes
What are exothermic and endothermic
P4(s) + 3O2(g) -> P4O6(s) HӨf= –1600 kJ mol–1 P4(s) + 5O2(g) -> P4O10(s) HӨf= –3000 kJ mol–1
What is the enthalpy change, in kJ mol–1, for the reaction below?
P4O6(s) + 2O2(g) -> P4O10(s)
–1400kJ mol^–1
Consider the reaction: N2O4 (g) → 2 NO2 (g) ΔHfθ = +57 kJ mol-1
Draw a potential energy profile for this reaction and explain whether NO2 or N2O4 is more stable.
Energy Diagram: Products > Reactants: N2O4 more stable than NO2
How much heat is required to raise the temperature of 250.0g of mercury by 52.0°C? (the specific heat for mercury is 0.14 J/g°C)
What is 1820J
What is the enthalpy change of the hydrogenation of an alkene in unsaturated oils for one mole of C = C bonds.
-123kJ
What is the difference between temperature and heat?
Heat is the energy transfer from one system to another
Temperature is the average molecular energy within the system
Calculate the enthalpy for this reaction:
2C(s) + H2(g) -> C2H2(g) ΔH° = ??? kJ
Given the following thermochemical equations: C2H2(g) + 5⁄2O2(g) ---> 2CO2(g) + H2O(ℓ)
ΔH° = -1299.5 kJ
C(s) + O2(g) ---> CO2(g) ΔH° = -393.5 kJ
H2(g) + 1⁄2O2(g) ---> H2O(ℓ) ΔH° = -285.8 kJ
+226.7 kJ
Use the enthalpy change of formation values below to calculate the enthalpy change for the following reaction:
4 NH3 (g) + 3 O2 (g) → 2 N2 (g) + 6 H2O (l)
ΔHfθ / kJ mol-1
NH3 (g) -46
H2O (l) -286
The standard enthalpy of formation for elements in their standard state is 0
-1532
The specific heat capacity of a liquid is 4.00 Jg-1C-1; 2000 J of heat energy are supplied to 100.0 g of the liquid. By how much would the temperature of the liquid increase?
5 C
Use the average bond enthalpies given in the IB Data Booklet to calculate the enthalpy change for the combustion of ethanol vapour, according to the equation:
C2H5OH (g) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (g)
- 1663 kJ mol-1