Thermochemistry Summative Assessment

Exothermic means a

reaction does what?

• Releases energy

• Absorbs energy

• Translates energy

• Has specific

  capacity

Heat is measured in 

• joules
• grams
• degrees celcius

The specific heat(c) of copper is 0.39 J/g °C. What is the temperature change(∆t) when 100 Joules of heat(Q) is added to 20 grams?

• 12.82 °C
• 24.12°C
• 351 °C

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

H₂ + 2 C + N₂ + 270.3 kJ --> 2 HCN
Is this reaction endothermic or exothermic?

• Endothermic 
• Exothermic

Tags

NGSS.HS-PS1-4

A 24.0 gram sample of copper was heated from 25.0^oC to 500.0^oC, 4378J of heat were absorbed, what is the specific heat of copper?

• .384
• 49909200
• 2.60
• 8.77

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

If ΔH is positive, heat would be shown on the _____ side of the thermochemical equation.

• Reactant
• Product

Tags

NGSS.HS-PS1-4

The enthalpy change for the reaction
C(s, graphite) + 1⁄2O₂(g) --> CO(g) cannot be measured directly since some carbon dioxide is always formed in the reaction.
It can be calculated using Hess’s Law and the enthalpy changes of combustion of graphite and of carbon monoxide.
C(s, graphite) + O₂(g) --> CO₂    ΔH=-394 kJmol^–1
CO(g) + 1⁄2O₂(g) --> CO₂  ΔH=-283 kJmol^–1  
The enthalpy change for the reaction of graphite with oxygen to give carbon monoxide is 

• -677 kJmol^–1 
• +111 kJmol^–1 
• -111 kJmol^–1 
• +677 kJmol^–1 

Tags

NGSS.HS-PS1-4

The enthalpies of combustion of C(s), H2(g) and C4H9OH(l) (in kJmol^-1) are as follows  
C(s) + O₂(g)   ->  CO₂(g)                                               ∆H=a
H₂(g) + ½O₂(g)   ->   H₂O(l)                                        ∆H=b
C₄H₉OH(l) + 6O₂(g)   ->   4CO₂(g) + 5H₂O(l)  ∆H=c
What is the enthalpy change for the reaction shown below?
  4C(g) + 5H₂(l) + ½O₂(g)   ->   C₄H₉OH(l)

• c – 4a – 5b
• 2a + 10b - c
• 4a + 5b - c
• 2a + 5b + c

Tags

NGSS.HS-PS1-4