Thermochemistry Practice

Calculate the enthalpy of the following reaction:
Ca(OH)₂ -> CaO + H₂O
ΔHf in kJ/mol:  
      Ca(OH)₂  -983.2
        CaO         -634.9
        H₂O         -285.5

• 62.8 kJ

• -62.8 kJ

• -1840.6

• 1840.6

Tags

NGSS.HS-PS1-4

In an endothermic reaction, the sum of the heats of formation of the products are____than the sum of the heats of formation of the reactants. Hint: is ΔH + or -? This about how you calculate ΔH

• less than

• greater than

• equal to

When heat flows from system to the surroundings that is an example of an ________________ process.

• exothermic

• endothermic

Tags

NGSS.HS-PS3-4

What device is used to measure the amount of heat involved in a chemical reaction or physical process?

• barometer

• calorimeter

• thermometer

2N₂ + 3H₂ --> 2NH₃ + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?

• 92 kJ

• 0.143 kJ

• 23 kJ

• 15 kJ

Tags

NGSS.HS-PS3-1

How much energy must be used to produce 4.75 mol of gaseous water?
H₂O (l) +  44.0 kJ --> H₂O (g)

• 207 kJ

• 9.36 kJ

• 206.8 kJ

• 9.362 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

4 PCl₅ + 3438 kJ --> P₄ + 10 Cl₂
How much energy is required to produce each mole of chlorine?

• 687.6 kJ

• 859.5 kJ

• 343.8 kJ

• 245.8 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

What mass of P₄ must be reacted to produce 5905 kJ of energy?
P₄ + 6Cl₂ --> 4PCl₃ + 2439 kJ

• 25.43 g

• 563.0 g

• 2.421 g

• 300.0 g

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

How much heat is needed to form 40.0 L of NO₂ from its elements at STP? 
N₂+ 2O₂ -> 2NO₂
ΔH = +67kJ

• 58.2 kJ

• 29.1

• 59.8

• 119.6

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

When you dropped a hot metal sample into room temperature water in the lab what happened?

• the heat from the metal traveled into the water

• the cool from the water traveled into the hot metal

• both of the other answers are correct

Tags

NGSS.HS-PS3-4