1.6 ENERGETICS

If the enthalpies of combustion of graphite, hydrogen and ethanol are -393, -286 and -1367 kJ mol-1 respectively, which one of the following is the enthalpy of formation of ethanol?
1. -139 kJ mol-1
2. -277 kJ mol-1
3. +277 kJ mol-1
4. +554 kJ mol-1
The following table shows the enthalpy change of neutralisation for some acid-base reactions:
acid
base

enthalpy change of neutralisation / kJ mol^-1
HCl
NaOH
-57.2
X

NaOH
-55.2
HCl

Y
-52.2
HNO₃

Z
-57.2

The identities of X, Y and Z respectively are
1. sulphuric acid / ammonia / potassium hydroxide
2. ethanoic acid / sodium hydroxide / ammonia
3. ethanoic acid / ammonia / potassium hydroxide
4. sulphuric acid / sodium hydroxide / ammonia
Given the bond dissociation energies:
C-C = 343 kJ mol^-1 ,   C-H = 414 kJ mol^-1
C=C = 611 kJ mol^-1,   H-H = 435 kJ mol^-1

What is the enthalpy change for the reaction?

CH₃CH=CH₂    +    H₂    =   CH₃CH₂CH₃
1. +125 kJ
2. -125 kJ
3. -560 kJ
4. +289 kJ
Given the bond energies:
C - C = 348 kJ mol^-1,  C - H = 412 kJ mol^-1
C = C = 612 kJ mol^-1,   H - H = 436 kJ mol^-1
C = O = 803 kJ mol^-1 ,   O - H = 464 kJ mol^-1
O = O = 497 kJ mol^-1,   O - O = 146 kJ mol^-1

Which of the following is the calculated enthalpy change for the reaction below?

CH₄   +   2O₂   =     CO₂   +   2H₂O
1. -323 kJ mol^-1
2. -6104 kJ mol^-1
3. -104 kJ mol^-1
4. -820 kJ mol^-1
Given the bond energies:
C - C = 348 kJ mol^-1,   C - H = 412 kJ mol^-1
C = C = 612 kJ mol^-1,   H - H = 436 kJ mol^-1

calculate the enthalpy change for the reaction

C₃H₆   +   H₂   =   C₃H₈
1. + 124 kJ mol^-1
2. +248 kJ mol^-1
3. -124 kJ mol^-1
4. -248 kJ mol^-1
If the enthalpies of combustion of carbon, hydrogen and methane are -395, -287 and -881 kJ mol^-1 respectively, what is the enthalpy of formation of methane in kJ mo^l-1?
1. -199
2. +88
3. -88
4. +199

acid	base	enthalpy change of neutralisation / kJ mol^-1
HCl	NaOH	-57.2
X	NaOH	-55.2
HCl	Y	-52.2
HNO₃	Z	-57.2

1.6 ENERGETICS

Multiple-choice exercise