Hess's Law

Using the equations below:

C_(s) + O_2(g) → CO_2(g) ∆H = –400 kJ

Mn_(s) + O_2(g) → MnO_2(s) ∆H = –500 kJ

what is ∆H (in kJ) for the following reaction?

MnO_2(s) + C_(s) → Mn_(s) + CO_2(g) ∆H = ??? kJ

• -900 kJ

• 900 kJ

• –100 kJ

• 100 kJ

Tags

NGSS.HS-PS1-4

Using the equations below

Cu_(s) + ¹/₂O_2(g) → CuO_(s) ∆H = –156 kJ

2Cu_(s) + O_2(g) → Cu₂O_(s) ∆H = –170 kJ

what is the value of ∆H (in kJ) for the following reaction?

CuO_(s) → Cu_(s) + ¹/₂O_2(g) ∆H = ???? kJ

• 156 kJ

• 170 kJ

• 326 kJ

• 14 kJ

Tags

NGSS.HS-PS1-4

The following equations show the oxidation of carbon and carbon monoxide to carbon dioxide.

C_(s) +O_2(g) → CO_2(g) ΔH = –x kJ mol^–1

CO_(g) + O_2(g) → CO_2(g) ΔH = –y kJ mol^–1

What is the enthalpy change, in kJ mol^–1, for the oxidation of carbon to carbon monoxide?

C_(s) + O_2(g) → CO_(g)

• x + y

• -x - y

• y - x

• x - y

Tags

NGSS.HS-PS1-4

The standard enthalpy change of formation values of two oxides of phosphorus are:

P_4(s) + 3O_2(g) → P₄O_6(s) ΔH_f = –1600 kJ mol^–1

P_4(s) + 5O_2(g) → P₄O_10(s) ΔH_f = –3000 kJ mol^–1

What is the enthalpy change, in kJ mol^–1, for the reaction below?

P₄O_6(s) + 2O_2(g) → P₄O_10(s)

• +4600

• +1400

• –1400

• –4600

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

From the following data,

H₂ (g) + Cl₂ (g) → 2HCl(g) ΔH° = -185 kJ,

2H₂ (g) + O₂ (g) →2H₂O(g) ΔH° = -484 kJ

calculate ΔH° for the following reaction.

4HCl(g) + O₂ (g) →2Cl₂ (g) + 2H₂O(g)

• 299 kJ

• -114 kJ

• -299 kJ

• 114 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Using the equation below:

C_(s) + O_2(g) → CO_2(g) ∆H = –400 kJ

what is ∆H (in kJ) for the following reaction?

CO_2(g) → C_(s) + O_2(g) ∆H = ?? kJ

• +400 kJ

• –400 kJ

• –800 kJ

Tags

NGSS.HS-PS1-4

Using the equations below:

Mn_(s) + O_2(g) → MnO_2(s) ∆H = –500 kJ

what is ∆H (in kJ) for the following reaction?

MnO_2(s) → Mn_(s) + O_2(g) ∆H = ??? kJ

• +500 kJ

• –500 kJ

Tags

NGSS.HS-PS1-4

Using the equations below:

Mn_(s) + O_2(g) → MnO_2(s) ∆H = –500 kJ

what is ∆H (in kJ) for the following reaction?

3 MnO_2(s) → 3 Mn_(s) + 3 O_2(g) ∆H = ??? kJ

• + 500 kJ

• –500 kJ

• –1500 kJ

• + 1500 kJ

Tags

NGSS.HS-PS3-1

Using the equation below:

C_(s) + O_2(g) → CO_2(g) ∆H = –400 kJ

what is ∆H (in kJ) for the following reaction?

4 CO_2(g) → 4 C_(s) + 4 O_2(g) ∆H = ?? kJ

• +400 kJ

• –400 kJ

• –1600 kJ

• + 1600 kJ

Tags

NGSS.HS-PS1-4

Using the equations below:

Mn_(s) + O_2(g) → MnO_2(s) ∆H = –500 kJ

what is ∆H (in kJ) for the following reaction?

3 Mn_(s) + 3 O_2(g) → 3 MnO_2(s) ∆H = ??? kJ

• + 500 kJ

• –500 kJ

• –1500 kJ

• + 1500 kJ

Tags

NGSS.HS-PS3-1