Energy in Chemical Reactions

Q1: How much energy is required to decompose 765 g of PCl₃, according to the reaction below? The molar mass of PCl₃ is 137.32 g/mol and may be useful.

4 PCl₃(g) → P₄(s) + 6Cl₂(g)

ΔH= +1207 kJ

• 2.31 × 10³ kJ

• 5.95 × 10³ kJ

• 4.33 × 10³ kJ

• 1.68 × 10³ kJ

Q2: Using the following equation for the combustion of octane, calculate the heat of reaction for 100.0 g of octane. The molar mass of octane is 114.33 g/mole.

2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O

ΔH= -11018 kJ

• 4.82 kJ

• 9.64 x 10³ kJ

• 4.82 x 10³ kJ

• 1.26 x 10⁴ kJ

Q3: How many kJ of heat are consumed when 5.10 g of H₂ (g) is formed according to the following reaction:

CH₃OH (l) → CO (g) + 2H₂ (g)

ΔH° = +128.1 kJ

• 653 kJ

• 326 kJ

• 62 kJ

• 162 kJ

Q4: How many kJ of heat are released in the combustion of 16.0 g of C₆H₆ ?

2C₆H₆ + 15O₂ →12CO₂ + 6H₂O

ΔH° = -6535 kJ

• 5.23 × 10⁴ kJ

• 669 kJ

• 2.68 × 10³ kJ

• 1.34 × 10³ kJ

Q5: According to the following thermochemical equation, what mass of HF (in g) must react in order to produce 345 kJ of energy?

SiO₂(s) + 4 HF(g) → SiF₄(g) + 2 H₂O(l)

ΔH = -184 kJ

• 107 g

• 42.7 g

• 150. g

• 173 g

Q6: What volume of benzene (C₆H₆, d= 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 1.5 x 10³ kJ of heat according to the following reaction?

2 C₆H₆(l) + 15 O₂(g) → 12 CO₂(g) + 6 H₂O(g)

ΔH= -6278 kJ

• 21 mL

• 75 mL

• 37 mL

• 42 mL

Q7: What mass of Cl₂ must be reacted to produce 5905 kJ of energy by the following reaction?

P₄ + 6Cl₂ → 4PCl₃

ΔH = + 2439 kJ

• 1030.g

• 171.6 g

• 515.0 g

• 300.0 g

Q8: How much energy is evolved during the reaction of 48.7 g of Al, according to the reaction below?

Fe₂O₃(s) + 2 Al(s) → Al₂O₃(s) + 2 Fe(s)

ΔH° = -852 kJ

• 769 kJ

• 207 kJ

• 415 kJ

• 241 kJ

Q9: How much heat is released by the reaction of 0.95 g of S according to the following equation:

2S (s) + 3O₂ (g) → 2SO₃ (g)

ΔH° = -790 kJ.

• 12 kJ

• 23 kJ

• 790 kJ

• 44 kJ

What letter represents the energy of the products?

• A
• B
• C
• D

Tags

NGSS.HS-PS1-4