Week 3 - MCQ - Unit 6 - Thermochemistry

Some average bond enthalpies, in kJ/mol, are as follows:
H-H = 436
Cl-Cl = 242
H-Cl = 431
What is the enthalpy change for the decomposition of hydrogen chloride?
2 HCl --> H₂ + Cl₂

• -184 kJ
• + 184 kJ
• - 247 kJ
• + 247 kJ

Tags

NGSS.HS-PS1-4

The average bond enthalpies for O-O and O=O are 146kJ/mol and 496kJ/mol respectively. Calculate the enthalpy change for the reaction shown.

• -102kJ

• +102kJ

• +146kJ

• -248 kJ

Tags

NGSS.HS-PS1-4

(Hess's Law)Calculate the ∆H for the following reaction: 2H₂O₂ →  2H₂O  + 1 O₂ 
You are given these two equations:
2H₂  +  O₂ → 2H₂O            ∆H  =  -572 kJ
H₂  +  O₂  →  H₂O₂            ∆H  =  -188 kJ 

• ∆H  =  -948 kJ 
• ∆H  =  -196 kJ 
• ∆H  =  -384 kJ 
• ∆H  =  -188 kJ 

Tags

NGSS.HS-PS1-4

(Hess's Law) Calculate the ∆H for the following reaction:
2CO  +  2NO →  2CO₂  +  N₂ 
You are given these two equations:
 2CO  +  O₂ →  2CO₂           ∆H  =  -566.0 kJ
N₂  +  O₂ →2NO                   ∆H  =  180.6 kJ

• ∆H  =  -385.4 kJ
• ∆H  =  -746.6 kJ
• ∆H  =  385.4 kJ
• ∆H  =  746.6 kJ

Tags

NGSS.HS-PS1-4

When the change in enthalpy (ΔH) is positive, the reaction is _____. When the change in enthalpy (ΔH) is negative, the reaction is _____.

• exothermic/endothermic

• endothermic/exothermic

Tags

NGSS.HS-PS1-4

The temperature of a sample of a compound with a mass of 1.0 g changed from 25°C to 50.4°C and absorbed 114 J of energy. What is the specific heat of the compound?

• 8.49 J/g°C

• 4.48 J/g°C

• 10.4 J/g°C

• 21.4 J/g°C

Tags

NGSS.HS-PS3-4

How much heat is released by 15.5 g of water when its temperature is cooled from 50°C to 20°C? The specific heat of water is 4.184 J/g°C.

• -1.946 J

• -1946 J

• -194.6 J

• -194600 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

When a nugget of pure gold is cooled from 842.26°C to 35°C, it released 5200.0 J of energy. The specific heat of gold is 0.129 J/g°C. Find the mass of the gold nugget.

• 208 g

• 50 g

• 67 g

• 11 g

Tags

NGSS.HS-PS3-4

Which enthalpy diagram (PE diagram) shows that the reaction

A₂ + X₂ → 2AX

is an ENDOthermic reaction that releases 550 kJ of heat?

• 
• 
• 
• 

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Which letter represents the potential energy of the reactants? (letters are in alphabetical order A-F starting at the far left line)

• A

• B

• C

• E

• F

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1