Enthalpy Change

Calculate the enthalpy change, in kJ/mol for the reaction

H_{2 (g)} + ½O_{2 (g)} → H₂O _(g)

Data of bond energy:

H−H = +436 kJ/mol

O=O = +498 kJ/mol

H−O = +464 kJ/mol

• −243 kJ/mol

• −6 kJ/mol

• +6 kJ/mol

• +221 kJ/mol

Tags

NGSS.HS-PS1-4

The standard enthalpy change for the combustion of graphite is −393.5 kJ/mol and that of diamond is −395.4 kJ/mol.

What is the standard enthalpy change for the reaction below, in kJ/mol?

C _{(s, graphite)} → C _{(s, diamond)}

• −1.9

• +1.9

• −788.9

• +788.9

Consider the following bond enthalpy values.

O−O = +146 kJ/mol

O−H = +463 kJ/mol

O=O = +496 kJ/mol

For the reaction

H−O−O−H _(g) → H−O−H _(g) + ½O=O _(g)

the enthalpy change, in kJ/mol, is ...

• −102

• +102

• +350

• +394

Using the data in the table below, calculate the standard enthalpy change, in kJ/mol, for the reaction between carbon disulfide, CS₂, and oxygen shown in the following equation.

CS_{2 (g)} + 3O_{2 (g)} → CO_{2 (g)} + 2SO_{2 (g)}

• −570

• −790

• −860

• −1080

Consider the following information of bond energy:

H−H = +436 kJ/mol

I−I = +151 kJ/mol

H−I = +299 kJ/mol

For the reaction:

H_{2 (g)} + I_{2 (g)} → 2HI _(g)

the enthalpy change, in kJ/mol is...

• +288

• +144

• −11

• −5.5

The standard enthalpy changes of formation of carbon dioxide and of methanoic acid are −394 kJ/mol and −409 kJ/mol respectively. Calculate the enthalpy change for the reaction

H_{2 (g)} + CO_{2 (g)} → HCOOH _(l)

• −803 kJ/mol

• −15 kJ/mol

• +803 kJ/mol

• +15 kJ/mol

Tags

NGSS.HS-PS1-4

Which of these diagram correctly represent an endothermic reaction?

• 
• 
• 
• 

Tags

NGSS.HS-PS1-4

Some mean bond enthalpy values are given in the table below.

H−H = +436 kJ/mol

I−I = +151 kJ/mol

H−I = +299 kJ/mol

What is the enthalpy change for the reaction shown below in kJ/mol?

H_{2 (g)} + I_{2 (g)} → 2HI _(g)

• 436 + 151 − 299 = + 288

• −436 − 151 + 299 = − 288

• +436 + 151 − (2 x 299) = − 11

• −436 − 151 + (2 x 299) = +11

The enthalpy change for the reaction to form hydrated sodium thiosulfate crystals cannot be measured directly. The following Hess cycle can be used. The enthalpy change for the reaction, ΔHr, is equal to ...

• ΔH₁ + ΔH₂

• ΔH₁ − ΔH₂

• − ΔH₁ − ΔH₂

• − ΔH₁ + ΔH₂

Example of endothermic reaction is ...

• Combustion

• Photosynthesis

• Neutralization

• Respiration

Tags

NGSS.HS-PS1-4