Energetics / Thermochemistry

What is the temperature of absolute zero in degrees Celsius?

Which statement best describes the Law of Conservation of Energy in a chemical system?

If a reaction in a calorimeter causes the temperature of the water to rise by $4.0 \, K$, and the mass of the water is $100 \, g$, what is the heat change $q$ in Joules? ($c = 4.18 \, J \cdot g^{-1} \cdot K^{-1}$)

Which enthalpy change is defined as the energy required to break one mole of a bond in a gaseous molecule into gaseous atoms?

If a reaction releases $1250 \, J$ of energy into $50.0 \, g$ of water initially at $20.0^{\circ}C$, what is the final temperature? ($c = 4.18 \, J \cdot g^{-1} \cdot K^{-1}$)

What happens to the magnitude of $\Delta T$ if the mass of water in a combustion experiment is halved, assuming the same amount of fuel is burned and there is no heat loss?

Calculate the temperature change when $2100 \, J$ of heat is supplied to $100 \, g$ of water.

A spirit burner containing butan-1-ol ($M = 74.12\,g\cdot mol^{-1}$) is used to heat $200\,g$ of water by $40.0^{\circ}C$. If $1.10\,g$ of butan-1-ol was consumed and the molar enthalpy of combustion is $-2676\,kJ\cdot mol^{-1}$, what was the percentage efficiency of the heat transfer?

Given the specific heat capacities: $c(H_{2}O, l) = 4.18\,J\cdot g^{-1}\cdot K^{-1}$ and $c(Cu, s) = 0.385\,J\cdot g^{-1}\cdot K^{-1}$. If $1000\,J$ of heat is added to $100\,g$ of each substance, which statement is true?

A student added $50.0\,cm^{3}$ of $1.0\,mol\cdot dm^{-3}\,HCl$ to $50.0\,cm^{3}$ of $1.0\,mol\cdot dm^{-3}\,NaOH$. The temperature rose from $21.5^{\circ}C$ to $28.2^{\circ}C$. The student then repeated the experiment using $50.0\,cm^{3}$ of $2.0\,mol\cdot dm^{-3}\,HCl$ and $50.0\,cm^{3}$ of $2.0\,mol\cdot dm^{-3}\,NaOH$. What would be the expected temperature rise?

Given that $2Fe + 1.5O_2 \rightarrow Fe_2O_3$ has $\Delta H = -824 \text{ kJ}$, what is $\Delta H$ for $2Fe_2O_3 \rightarrow 4Fe + 3O_2$?

What is the enthalpy change for the process $O_2(g) \rightarrow O_2(l)$ called?

In the reaction $A + B \rightarrow C + D$, if the sum of enthalpies of formation of $(C+D)$ is less than the sum of $(A+B)$, the reaction is:

Which of the following is equivalent to the enthalpy of formation of $CO_2(g)$?

Using the following reactions: $2C(s) + O_2(g) \rightarrow 2CO(g) \quad \Delta H = -222 \text{ kJ}$ $SnO_2(s) + 2CO(g) \rightarrow Sn(s) + 2CO_2(g) \quad \Delta H = +15 \text{ kJ}$ $C(s) + O_2(g) \rightarrow CO_2(g) \quad \Delta H = -394 \text{ kJ}$ Calculate $\Delta H$ for $Sn(s) + O_2(g) \rightarrow SnO_2(s)$.

Calculate the enthalpy change for the reaction $NH_3(g) + HCl(g) \rightarrow NH_4Cl(s)$ given: $\Delta H_f^{\ominus} [NH_3(g)] = -46.1 \text{ kJ mol}^{-1}$ $\Delta H_f^{\ominus} [HCl(g)] = -92.3 \text{ kJ mol}^{-1}$ $\Delta H_f^{\ominus} [NH_4Cl(s)] = -314.4 \text{ kJ mol}^{-1}$

Which of the following would not be needed to calculate the enthalpy of formation of liquid ethanol using Hess's Law and combustion data?

Calculate the average $C-F$ bond enthalpy in $CF_4(g)$ given: $\Delta H_f^{\ominus} [CF_4(g)] = -680 \text{ kJ mol}^{-1}$ $\Delta H_{at}^{\ominus} [C(s)] = +717 \text{ kJ mol}^{-1}$ $E(F-F) = 158 \text{ kJ mol}^{-1}$

Calculate the enthalpy change for $Cu(s) + 2H_2SO_4(l) \rightarrow CuSO_4(s) + SO_2(g) + 2H_2O(l)$ given: $\Delta H_f^{\ominus} [H_2SO_4(l)] = -814 \text{ kJ mol}^{-1}$ $\Delta H_f^{\ominus} [CuSO_4(s)] = -770 \text{ kJ mol}^{-1}$ $\Delta H_f^{\ominus} [SO_2(g)] = -297 \text{ kJ mol}^{-1}$ $\Delta H_f^{\ominus} [H_2O(l)] = -286 \text{ kJ mol}^{-1}$

Find the lattice enthalpy of $Li_2O(s)$ given: $\Delta H_f = -598 \text{ kJ mol}^{-1}$ $\Delta H_{at} [Li] = +159 \text{ kJ mol}^{-1}$ $IE_1 [Li] = +520 \text{ kJ mol}^{-1}$ $\Delta H_{at} [O_2] = +249 \text{ kJ mol}^{-1}$ (for 0.5 moles of $O_2$) $EA_1 [O] = -141 \text{ kJ mol}^{-1}$ $EA_2 [O] = +744 \text{ kJ mol}^{-1}$

For the reaction $2H_{2}(g) + O_{2}(g) \rightarrow 2H_{2}O(g)$, how many $O-H$ bonds are formed?

Which of these bonds is typically the most difficult to break in organic chemistry?

What can be concluded if the $\Delta H$ of a reaction calculated from bond enthalpies is zero?

Which of the following bonds has the lowest bond enthalpy?

Which of the following will result in an increase in the calculated value of bond enthalpy for a $C-C$ bond?

If the $\Delta H$ for the reaction $A_{2} + B_{2} \rightarrow 2AB$ is negative, which of the following must be true?

Why is the bond enthalpy of $N \equiv N$ ($945$ kJ/mol) so much higher than $N-N$ ($158$ kJ/mol)?

Which of the following is a limitation of using bond enthalpies to calculate the enthalpy of a reaction?

Calculate the enthalpy change for the reaction: $HC \equiv CH(g) + 2H_2(g) \rightarrow CH_3CH_3(g)$. Data: $C \equiv C = 839$, $H-H = 436$, $C-C = 347$, $C-H = 413$ kJ/mol.

Why is the bond enthalpy of the $N-N$ bond in $N_2H_4$ ($158$ kJ/mol) much lower than the $F-F$ bond in $F_2$ ($158$ kJ/mol)? (Note: values are similar, but conceptual context differs). Actually, comparing $N-N$ to $O-O$ or $C-C$: why is $N-N$ single bond relatively weak?

1. Energy cycles (HL): practice question 1 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 2 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 3 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 4 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 5 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 6 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 7 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 8 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 9 for Energetics / Thermochemistry?

1. Energy cycles (HL): practice question 10 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 1 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 2 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 3 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 4 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 5 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 6 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 7 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 8 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 9 for Energetics / Thermochemistry?

1. Entropy and spontaneity (HL): practice question 10 for Energetics / Thermochemistry?