Thermochemical Reactions

A positive ΔH means that:

• In order for the reaction to happen, heat must be input. It is exothermic

• In order for the reaction to happen, heat must be input. It is endothermic.

• When the reaction happens, heat is released. It is exothermic

• When the reaction happens, heat is released. It is endothermic

Tags

NGSS.HS-PS3-1

Is the following exothermic or endothermic?

• Endothermic

• Exothermic

Tags

NGSS.HS-PS1-4

Calculate ΔH when 2 moles of ethanol (C₂H₅OH) reacts with excess oxygen according to the following thermochemical equation?

• -2733.4 kJ

• -683.35 kJ

• -1366.7 kJ

• -910.67 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

What is ΔH if 2 mol of O₂(g) is reacted in this reaction?

• -570 kJ

• -71.45 kJ

• -1143.2 kJ

• -142.9 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

reactions absorb energy around it making the area feel 'colder.' reactions release energy to the surrounding area making the area feel 'warmer.'

• Endothermic

• Exothermic

• Isothermic

Tags

NGSS.HS-PS1-4

require(s) the addition of energy for a reaction to occur.

• Endothermic Reactions

• Exothermic Reactions

• Combustion Reactions

• Condensation

Tags

NGSS.HS-PS1-4

The breakdown of Silver Chloride absorbs a great deal of energy from sunlight as it progresses; it can be described as both ​ (a)   and​ ​ (b)   .

• exothermic

• decomposition

• endothermic

• synthesis

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

In an endothermic reaction, energy is

(a)  

• absorbed

• released

Tags

NGSS.HS-PS1-4

In an endothermic reaction ​ (a)   is required to break the bonds of the reactants than is ​ ​ (b)   when products form.

• more energy

• released

• less energy

• absorbed

Tags

NGSS.HS-PS1-4

The enthalpy change for the reaction C(s, graphite) + 1⁄2O₂(g) --> CO(g) cannot be measured directly since some carbon dioxide is always formed in the reaction. It can be calculated using Hess’s Law and the enthalpy changes of combustion of graphite and of carbon monoxide. C(s, graphite) + O₂(g) --> CO₂ ΔH=-394 kJmol^–1 CO(g) + 1⁄2O₂(g) --> CO₂ ΔH=-283 kJmol^–1 The enthalpy change for the reaction of graphite with oxygen to give carbon monoxide is

• -677 kJmol^–1

• +111 kJmol^–1

• -111 kJmol^–1

• +677 kJmol^–1

Tags

NGSS.HS-PS1-4