AP Chemistry Thermochemistry Bond Enthalpies

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

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

In an endothermic reaction, do reactants have a higher or lower energy than the products? 

• Higher
• Lower

Tags

NGSS.HS-PS1-4

In a laboratory experiment a student was using Styrofoam cups and foil to reduce the energy lost during an exothermic reaction.  The reaction constantly had a temperature probe in it.  Towards the end of the reaction the student noticed the temperature in the cups was going down (opposite what they thought is should).  The student concluded that the energy was destroyed within the system.  This student's reasoning violates what law?

• Law of Conservation of Mass
• Law of Enthalpy
• First Law of Thermodynamics
• Law of Heat Transfer

Tags

NGSS.HS-PS3-4

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

• Endothermic 
• Exothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

H₂ + 2 C + N₂ + 270.3 kJ --> 2 HCN
Is this reaction endothermic or exothermic?

• Endothermic 
• Exothermic

Tags

NGSS.HS-PS1-4

If ΔH is positive, heat would be shown on the _____ side of the thermochemical equation.

• Reactant
• Product

How much heat does an aluminum block absorb if 10.00 grams ae heated from 25.0^oC to 50.0^oC?

The specific heat of aluminum is 0.900J/g^oC

• 450
• -450
• 225
• -225

Tags

NGSS.HS-PS3-1

Using the enthalpies of formation, calculate the enthalpy of the following reaction:
Ca(OH)₂ -> CaO + H₂O
ΔHf in kJ/mol:  
      Ca(OH)₂  -983.2
        CaO         -634.9
        H₂O         -285.5

• 62.8 kJ
• -62.8 kJ
• -1840.6
• 1840.6

Tags

NGSS.HS-PS1-4

The SI unit of heat and energy is the __________.

• calorie
• heat
• joule
• watt