Calorimetry and Chemical Energy Flashcards

A set of vocabulary flashcards covering calorimetry, the differences between endothermic and exothermic reactions, and specific data points from experimental observations.

Calorimeter

An apparatus used to measure temperature changes over time for reactants and products to determine energy flow.

Endothermic

A process where energy is transferred via heating from the surroundings to the chemical reaction, causing the reaction to feel cold to the touch.

Exothermic

A process where energy is transferred via heating from the chemical reaction to the surroundings, causing the reaction to feel warm to the touch.

$$+\Delta H_{rxn}$$

The sign for the enthalpy of reaction in an endothermic process, where the arrow for $\Delta H_{rxn}$ points up on a reaction progress diagram.

$$-\Delta H_{rxn}$$

The sign for the enthalpy of reaction in an exothermic process, where the arrow for $\Delta H_{rxn}$ points down on a reaction progress diagram.

Energy required to break bonds (Endothermic)

The energy required to break the bonds of the reactants is greater than the energy released to form the bonds of the products.

Energy released to form bonds (Exothermic)

The energy required to break the bonds of the reactants is less than the energy released to form the bonds of the products.

Endothermic Reaction Equation

A chemical equation where "Energy" is written on the reactants side, such as $2H_2O(l) + \text{energy} \rightarrow 2H_2(g) + O_2(g)$.

Exothermic Reaction Equation

A chemical equation where "Energy" is written on the products side, such as $2H_2(g) + O_2(g) \rightarrow 2H_2O(l) + \text{energy}$.

$NH_4NO_3$ experiment

When $5.00\,g$ of this substance is added to $150.0\,ml$ of water, the temperature of the solution drops from $22.0^{\circ}C$ to $16.5^{\circ}C$, indicating an endothermic reaction.

$CaCl_2$ experiment

When $5.00\,g$ of this substance is added to $150.0\,ml$ of water, the temperature of the solution increases from $22.0^{\circ}C$ to $31.5^{\circ}C$, indicating an exothermic reaction.

Reactants in Endothermic Reactions

In these reactions, the reactants store less energy chemically than the products.

Reactants in Exothermic Reactions

In these reactions, the reactants store more energy chemically than the products.

Endothermic Examples

Processes including ice melting, water boiling, and adding baking soda to vinegar.

Exothermic Examples

Processes including wood burning, water freezing, and burning a Cheese Puff.