Enthalpy

ΔH value in an endothermic reaction is a positive number.

• True
• False

Tags

NGSS.HS-PS1-4

Match the definition below to the correct term.

The enthalpy change that takes place when one mole of a compound is formed from its elements in their standard states under standard conditions.

• The enthalpy of neutralisation

• The enthalpy of combustion

• The enthalpy of formation

• The enthalpy of reaction

Define 'Enthalpy'

• a) Energy stored in the movement of molecules in a substance
• b) The opposite of temperature
• c) The temperature of a molecule
• d) Energy stored in the chemical bonds in a substance

Tags

NGSS.HS-PS1-4

What does the circle mean in ΔH°?

• Standard Conditions (T=298.15 K P=1 atm)

• Standard Temperature and Pressure (T=273.15 K P=1 atm)

• Degree K

• Degree C

How do you calculate Enthalpy of a reaction?

• ΔH = ΔH_products - ΔH_reactants

• ΔT = q / mC

• ΔG = ΔH -TΔS

• E = mc²

Tags

NGSS.HS-PS1-4

"Heat change when 1 mole of gaseous atom is formed from its element at standard states" is the definition for _______.

• standard enthalpy of formation

• standard enthalpy ofhydration

• electron affinity

• standard enthalpy of atomisation

Name the type of enthalpy for the following reaction:

Na⁺ (g) --> Na⁺ (aq) ΔH = -364 kJmol^-1

• Standard enthalpy of neutralisation, ΔH_neut^o

• Standard enthalpy of solution, ΔH_soln^o

• Standard enthalpy of hydration, ΔH_hyd^o

• lattice energy, ΔH_lattice^o

Tags

NGSS.HS-PS1-4

Define standard enthalpy of combustion.

• Heat released when one mole of substance is burnt completely in excess oxygen.

• Heat absorbed when one mole of substance is burnt completely in excess oxygen under standard state.

• Heat released when one mole of substance is burnt completely in excess oxygen under standard state.

• Heat change when one mole of substance is burnt partially in excess oxygen under standard state.

Tags

NGSS.HS-PS1-4

Which of the following has a ΔH_f^o value of 0?

• Br₂(g)

• N(g)

• CO(g)

• N₂(g)

Tags

NGSS.HS-PS1-4

Which of the equation below refers to the standard enthalpy of formation, ΔH_f^o?

• Na(g) ---> Na⁺(g) + e^- ΔH = -364 kJmol^-1

• C₂H₅OH(l) + 3O₂(g) ---> 2CO₂(g) + 3H₂O (l) ΔH = - 1286 kJmol^-1

• 2C(s) + 2H₂(g) ---> C₂H₄ (g) ΔH = - 52.3 kJmol^-1

• Na⁺(g) ---> Na⁺(aq) ΔH = - 364 kJmol^-1

Tags

NGSS.HS-PS1-4