Reactivity 1. What drives chemical reactions?

Standard enthalpy of formation is defined for the formation of how many moles of a compound?

Which value of $\Delta H$ represents the most exothermic reaction?

Enthalpy change of neutralization for a strong acid and a strong base is approximately $-57\,kJ mol^{-1}$. This reaction is:

What is the molar mass of methanol ($CH_3OH$)? (Atomic masses: $C=12, H=1, O=16$)

Two calorimetry experiments are performed to determine the enthalpy of neutralization of $HCl(aq)$ and $NaOH(aq)$. The diagram below summarizes the volumes and concentrations used in each experiment. If the temperature rise in Experiment 1 is recorded as $\Delta T_1$, which expression represents the expected temperature rise, $\Delta T_2$, in Experiment 2?

If a reaction is carried out at constant pressure, the heat change ($q_p$) is equal to:

Which of the following statements about an isolated system is true?

Which combination will produce an enthalpy change that is exactly zero by definition?

How much energy is needed to decompose $34.0\ g$ of $NH_3(g)$ into its elements? ($\Delta H_f [NH_3] = -46.0\ kJ\ mol^{-1}$)

A student measures the enthalpy of neutralization of $HCl$ and $NaOH$. He calculates $\Delta H = -55\ kJ\ mol^{-1}$. If he repeats the experiment using $CH_3COOH$ and $NaOH$, what is the most likely value for $\Delta H$?

Hess's Law is a specific application of which law?

Which value is usually calculated first before finding the molar enthalpy change in a laboratory experiment?

If the products of a reaction have a lower total enthalpy than the reactants, the reaction must be:

For the combustion of hydrogen: $2H_2(g) + O_2(g) \rightarrow 2H_2O(l)$, $\Delta H$ is $-572$ kJ. What is the standard enthalpy of combustion of hydrogen in kJ/mol?

In the enthalpy cycle for the formation of an ionic compound, which step is typically the most exothermic?

Which of the following would be the most accurate way to find the enthalpy of a reaction that is too slow to measure directly?

If \\Delta H_f^\\circ [CO(g)] = -110.5 kJ mol^{-1} and \\Delta H_f^\\circ [CO_2(g)] = -393.5 kJ mol^{-1}, what is $\\Delta H$ for $2CO(g) + O_2(g) \rightarrow 2CO_2(g)$?

Consider the following thermochemical data:

• $N_2(g) + 2O_2(g) \rightarrow 2NO(g) + O_2(g) \quad \Delta H = +180 \text{ kJ}$
• $2NO(g) + O_2(g) \rightarrow 2NO_2(g) \quad \Delta H = -114 \text{ kJ}$
• $N_2(g) + 2O_2(g) \rightarrow N_2O_4(g) \quad \Delta H = +9 \text{ kJ}$

Based on the enthalpy cycle shown in the diagram, what is the enthalpy change, in kJ, when 9.20 g of $NO_2(g)$ is converted into $N_2O_4(g)$? (Assume $M_r$ of $NO_2 = 46.0$)

What is the enthalpy change for the reaction $X \rightarrow Z$ given the following cycle?

The enthalpy of formation of $CO_2(g)$ is $-394 \text{ kJ mol}^{-1}$. Which of the following equals this value?

A student conducts an experiment to determine the energy content of a fuel. The flowchart shows the steps taken to process the data from a spirit burner. What is the final value calculated using the 'Moles of Fuel'?

A fuel undergoes combustion to release energy. This process involves an initial energy investment to break bonds, followed by energy release when new bonds form. Based on the diagram, which condition results in the reaction being exothermic?

Which change of state is exothermic?

Standard enthalpy of formation is measured for the formation of how many moles of a substance?

Bond enthalpy for $H-H$ is $436\,kJ\,mol^{-1}$. What is the energy change for the process $H_2(g) \rightarrow 2H(g)$?

Calculate $\Delta H$ for $2A + B \rightarrow D$ using: $2A + B \rightarrow C \quad \Delta H = x$ $D \rightarrow C \quad \Delta H = y$

The enthalpy of formation of $HI(g)$ is $+26\,kJ\,mol^{-1}$. Which equation represents this?

A student carries out a neutralization reaction between $NaOH$ and $HCl$. If they use double the volume of both solutions at the same concentration, how will the temperature change ($\Delta T$) and the heat evolved ($q$) compare to the original experiment?

Which statement about the stability of compounds is correct based on their enthalpies of formation?

Calculate $\Delta H$ for the following reaction: $C_2H_4(g) + 3O_2(g) \rightarrow 2CO_2(g) + 2H_2O(l)$. $\Delta H_f$ ($\text{kJ mol}^{-1}$): $C_2H_4(g) = +52$; $CO_2(g) = -394$; $H_2O(l) = -286$.