MYP 10 Chemistry 2013-14
Energetics Worksheet 1
Specific Heat Capacity / Enthalpy Change
Name: _________________________________ ( )
Class: _________ Date: _____________
_________________________________________________________________________________
5.1 Exothermic and endothermic reactions

5.1.1 Define the terms exothermic reaction, endothermic reaction and standard enthalpy change or reaction ( H )
5.1.2 State that combustion and neutralization are exothermic processes.
5.1.3 Apply the relationship between temperature change, enthalpy change and the classification of a reaction as endothermic or
exothermic.
5.1.4 Deduce, form an enthalpy level diagram, the relative stabilities of reactants and products, and the sign of the enthalpy change for the
reaction.
5.2 Calculation of enthalpy changes
5.2.1 Calculate the heat energy change when the temperature of a pure substance is changed.
5.2.2 Design suitable experimental procedures for measuring the heat energy changes of reactants.
5.2.3 Calculate the enthalpy change for a reaction using experimental data on temperature changes, quantities of reactants and mass of
water.
5.2.4 Evaluate the results of experiments to determine enthalpy changes.
5.3 Hess’s law
5.3.1 Determine the enthalpy change of a reaction that is the sum of two or three reactions with known enthalpy changes.
5.4 Bond enthalpies
5.4.1 Define the term average bond enthalpy.
5.4.2 Explain, in terms of average bond enthalpies, why some reactions are exothermic and others are endothermic.
5.4 Standard enthalpy changes of reaction (HL)
5.4.1 Define and apply the terms standard state, standard enthalpy change of formation (ΔHfθ) and standard enthalpy change of
combustion (ΔHcθ).
5..4.2 Determine the enthalpy change of a reaction using standard enthalpy changes of formation and combustion
5.5 Entropy (HL)
5.5.1 State and explain the factors that increase the entropy in a system.
5.5.2 Predict whether the entropy change (ΔS) for a given reaction or process is positive or negative.
5.5.3 Calculate the standard entropy change for a reaction (ΔSθ) standard entropy values of (Sθ)
5.6 Spontaneity (HL)
5.6.1 Predict whether a reaction or process will be spontaneous by using the sign of ΔGθ.
5.6.2 Calculate ΔGθ for a reaction using the equation ΔGθ = ΔHθ - TΔSθ by using values of the standard free energy change of formation,
ΔGf θ.
5.6.3 Predict the effect of change in temperature on the spontaneity of a reaction, using standard entropy and enthalpy changes and the
equation ΔGθ = ΔHθ - TΔSθ.
q = m c ΔT
where c = specific heat capacity and q = heat energy
Note: (i) ∆T = (Tfinal – Tinitial).
(ii) When heat is absorbed by water, c = 4.18 Jg-1K-1 ; density of water = 1gcm-3)
(iii) A temp rise of 1K is the same as a temp rise of 1°C
1. For the study of standard enthalpy changes, the standard pressure is _______atmosphere or ______kPa
while the standard temperature is _______K. For solutions, their standard _____________ is 1 moldm-3.
2. Standard enthalpy change of _______________ is the enthalpy change when 1 mole of the substance is
completely burnt in oxygen under standard condition.
3. Standard enthalpy heat of ________________ is the enthalpy change when 1 mole of a substance is
formed from its elements in their standard states.
4. Standard enthalpy change of _______________ is the enthalpy change when 1 mole of __________ is
formed when an acid reacts with an alkali under standard conditions.
5. Standard enthalpy of solution is the enthalpy change when ______________________________________
________________________________________________________________________.
6. In a simple calorimetry, it is usually assumed that
 there is no _______________ loss to the surroundings.
 the _________________________ of the solution is the same as that of water.
 the _____________________ is done under standard conditions.
7. How many joules of heat are needed to raise the temperature of 10.0 g of aluminium from 22°C to 55°C,
if the specific heat of aluminium is 0.90 J g-1°C-1 ?
8. To what temperature will a 50.0 g piece of glass raise if it absorbs 5275 joules of heat and its specific
heat capacity is 0.50 J g-1°C-1? The initial temperature of the glass is 20.0°C.
9. If a sample of chloroform is initially at 25°C, what is its final temperature if 150.0 g of chloroform
absorbs 1.0 kilojoules of heat, and the specific heat of chloroform is 0.96 J g-1°C-1?
10. Calculate the enthalpy of combustion of ethanol (C2H5OH) from the following data. Assume all the heat
from the reaction is absorbed by water. Compare your value with the IB Data booklet value and suggest
reasons for any differences.
Mass of water in copper calorimeter / g
Temperature increase in water / 0C
Mass of ethanol (C2H5OH)
200.00
13.00
0.45
11. A spirit burner containing propan-1-ol (C3H7OH) is used to heat up a beaker of water (400cm3) from
20°C to 70°C. (Given that H c [propan-1-ol] =  2010kJmol1 )
(a) Calculate the theoretical mass of propan-1-ol needed for the heating process.
(b) Would you expect a larger or smaller actual mass of propan-1-ol needed?
(c) Explain your answer in part(b).
12. A 65.00 cm3 sample of 0.50M sulphuric acid at 25.0°C was mixed with 50.00 cm3 of 0.90M potassium
hydroxide solution at 25.0°C in a simple calorimeter. The highest temperature recorded after mixing was
30.3°C. (Assume that the specific heat capacity and density of the resultant solution are 4.18 Jg-1K-1 and
1.01gcm-3 respectively, and there is no heat lost to the surroundings.)
(a) Write an equation for the reaction.
(b) Write an equation that can represent standard enthalpy change of neutralisation between sulphuric acid and
potassium hydroxide.
(c) Determine standard enthalpy change of neutralisation between sulphuric acid and potassium hydroxide.
13. In aqueous solution, lithium hydroxide and hydrochloric acid react as follows.
LiOH(s) + HCl(aq)  LiCl(aq) + H2O(l)
The data below is from an experiment to determine the standard enthalpy change of this reaction.
50.0 cm3 of a 0.500 mol dm-3 solution of LiOH was mixed rapidly in a glass beaker with 50.0 cm3 of a
0.500 mol dm-3 solution of HCl.
Initial temperature of each solution = 20.60C
Final temperature of the mixture = 24.10C
(a) State, with a reason, whether the reaction is exothermic or endothermic.
(b) Explain why the solutions were mixed rapidly.
(c) Calculate the enthalpy change of this reaction in kJmol-1. Assume that the specific heat capacity of the solution
is the same as that of water.
(d) Identify the major source of error in the experimental procedure described above. Explain how it could be
minimized.
(e) The experiment was repeated but with an HCl concentration of 0.520 moldm-3 instead of 0.500 moldm-3. State
and explain what the temperature change would be.
[(c)-58.5kJmol-1]