Standard Heat of Formation

In an endothermic reaction, the sum of the heats of formation of the products are____than the sum of the heats of formation of the reactants. Hint: is ΔH + or -? This about how you calculate ΔH

• less than
• greater than
• equal to

Tags

NGSS.HS-PS3-1

• -393.5 kJ/mol

• -566.0 kJ/mol

• 566.0 kJ/mol

• -369 kJ/mol

Tags

NGSS.HS-PS1-4

Which one of the following expressions is the correct way to calculate standard enthalpy change for the combustion of propane?

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)

Use your heats of formation table for reference.

• [103.85 + (5 × 286)] – [-393.5 + -285.8]

• [-103.85 + 0] + [(3 x -393.5) + (4 x -285.8)]

• [-103.85 + 0] – [(3 x -393.5) + (4 x -285.8)]

• [(3 x -393.5) + (4 x -285.8)] + [-103.85 + 0]

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

What is the heat of formation for 6 moles of ethanol? Use your heats of formation table for reference.

• -1666.2 kJ/mol

• -277.7 kJ/mol

• 52.3 kJ/mol

• Only able to calculate in a reaction

• -890.25 kJ/mol

• -604.45 kJ/mol

• -754.15 kJ/mol

• No way to tell

Tags

NGSS.HS-PS1-4

What is the heat of formation for 8 moles of ammonia? Use your heats of formation table for reference.

• -369.52 kJ/mol

• -46.19 kJ/mol

• -92.38 kJ/mol

• -102.4 kJ/mol

Tags

NGSS.HS-PS1-4

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

NGSS.HS-PS3-1