Chemistry Chapter on Enthalpy Changes

False (B)

$ riangle H = ext{sum of (n} riangle H^°){products} - ext{sum of (n} riangle H^°){reactants}$

<p>formation enthalpy</p> Signup and view all the answers

<p>Enthalpy Change = The difference between the enthalpy of products and reactants Formation Enthalpy = Energy change associated with the formation of a compound $ riangle H$ = Symbol representing change in enthalpy Reactants = Substances consumed in a chemical reaction</p> Signup and view all the answers

<p>The substance is a pure element (A)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>It indicates that energy is released when the compound is formed.</p> Signup and view all the answers

<p>stable</p> Signup and view all the answers

<p>Sucrose (C12H22O11) = -2226.1 kJ/mol Oxygen (O2) = 0 kJ/mol Carbon (C) = 0 kJ/mol Water (H2O) = -285.8 kJ/mol</p> Signup and view all the answers

<p>-198.7 kJ/mol (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Negative</p> Signup and view all the answers

<p>Negative</p> Signup and view all the answers

<p>Ethanol = C₂H₅OH Carbon dioxide = CO₂ Water = H₂O Hexane = C₆H₁₄</p> Signup and view all the answers

<p>Diagram B (D)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>+164.7 kJ</p> Signup and view all the answers

<p>energy conservation</p> Signup and view all the answers

<p>+164.7 kJ = Enthalpy change of the reaction +658.8 kJ/mol = Enthalpy change per mole of hydrogen</p> Signup and view all the answers

<p>It is independent of the route of the reaction. (C)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Germain Henri Hess</p> Signup and view all the answers

<p>net enthalpy</p> Signup and view all the answers

<p>Hess' Law = Enthalpy change is independent of the reaction route ΔHnet = Total enthalpy change of a chemical reaction Enthalpy = Heat content of a system Route = Path taken in a reaction</p> Signup and view all the answers

<p>-109.3 kJ (C)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>-285.8 kJ</p> Signup and view all the answers

<p>-393.5 kJ</p> Signup and view all the answers

<p>C₂H₄(g) + 3 O₂(g) → 2 CO₂(g) + 2 H₂O(l) = -1411 kJ C₂H₆(g) + 7/2 O₂(g) → 2 CO₂(g) + 3 H₂O(l) = -1560 kJ (flipped) H₂(g) + 1/2 O₂(g) → H₂O(l) = -285.8 kJ C(s) + O₂(g) → CO₂(g) = -393.5 kJ</p> Signup and view all the answers

The energy change that occurs during a chemical reaction.

The energy change during the formation of one mole of a compound from its elements in their standard states.

The difference between the sum of the formation enthalpies of the products and the reactants.

The standard state for a substance is its most stable form at 1 atm pressure and usually at 298 K (25 °C).

The change in enthalpy when one mole of a substance is formed from its elements in their standard states. This can be positive (endothermic reaction) or negative (exothermic reaction).

The standard molar enthalpy of formation (ΔH°) is the change in enthalpy that occurs when one mole of a compound is formed from its elements in their standard states under standard conditions (SATP).

A compound's thermal stability refers to its resistance to decomposition when heated. The lower its ΔH° (more negative), the more stable it is.

The standard molar enthalpy of formation (ΔH°) for elements in their standard state is 0 kJ/mol.

The ΔH° of a compound represents the energy released or absorbed when 1 mole of that compound is formed from its elements in their standard states.

Standard conditions are defined as SATP (Standard Ambient Temperature and Pressure): 298 K (25°C) and 100 kPa.

A chemical reaction involving the rapid reaction between a substance with an oxidant, usually oxygen, to produce energy in the form of heat and light.

The change in enthalpy that occurs during a chemical reaction. It is positive for endothermic reactions and negative for exothermic reactions.

The amount of energy required to break the bonds in the reactants of a reaction. It is always a positive value.

The amount of energy released when new bonds are formed in the products of a reaction. It is always a negative value.

The enthalpy change per mole of a specific substance in a chemical reaction.

The balanced chemical equation for the reaction when a substance reacts with oxygen to produce carbon dioxide and water.

A negative enthalpy change indicates that the reaction releases heat to the surroundings, meaning it is exothermic.

A chemical reaction that releases energy, often in the form of heat, to the surrounding environment.

The total enthalpy change in a reaction is the same, regardless of the individual steps involved.

The sum of the enthalpy changes for each step in a reaction equals the overall enthalpy change.

A chemical reaction that is broken down into multiple steps.

A reaction that releases energy into the surroundings.

The enthalpy change for a reaction that is carried out under standard conditions.

The enthalpy change for the formation of one mole of a substance from its elements in their standard states.

The standard state for an element is its most stable form at 1 atm pressure and 298 K (25 °C).