Thermochemistry

In an endothermic reaction the system is releasing energy.

• True
• False

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Refer the the following question:
2N₂ + 3H₂ --> 2NH₃ + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?

• 92 kJ
• 0.143 kJ
• 23 kJ
• 15 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

How much energy must be used to produce 4.75 mol of gaseous water?
H₂O (l) +  44.0 kJ --> H₂O (g)

• 207 kJ
• 9.36 kJ
• 206.8 kJ
• 9.362 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

H₂ + Cl₂ --> 2 HCl + 1845 kJ
Is this reaction endothermic or exothermic?

• Endothermic 
• Exothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Heat is measured in 

• joules
• grams
• degrees celcius

5.0 g of copper was heated from 20°C to 80°C. How much energy was used to heat Cu? (Specific heat capacity of Cu is 0.092 J/g °C)

• 27.6 J

• 36.8J

• 9.2 J

• 0.91 J

Tags

NGSS.HS-PS3-4

Maria finds that it takes exactly 3,748 Joules to raise the temperature of her coffee from 18°C to 80°C. If the mass of her coffee is 89 g, what is the specific heat of the coffee?

• 0.526 J/g°C

• 42.11 J/g°C

• 60.45 J/g°C

• 0.679 J/g°C

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

According to the diagram, what is ΔH for the reaction?

• 80 kJ

• -80 kJ

• 240 kJ

• -160 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

The amount of energy that is absorbed or lost by a system as heat during a process at constant pressure

• a) enthalpy

• b) entropy

• c) specific heat

• d) energy

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