Thermochemistry Unit Review

• Endothermic

• Exothermic

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NGSS.HS-PS1-4

• endothermic because absorbing energy

• endothermic because releasing energy

• exothermic because releasing energy

• exothermic because absorbing energy

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NGSS.HS-PS1-4

NGSS.HS-PS3-1

What is the relationship between the magnitude of ΔH and the quantities of reactants and products?

• proportional

• inversely proportional

• no relationship

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NGSS.HS-PS1-4

If the reactants have more energy than products, that reaction is:

• Endothermic

• Exothermic

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NGSS.HS-PS1-4

Which of these phase changes is exothermic?

(Select all that apply)

• Condensation

• Vaporization

• Deposition

• Melting

Heat of sublimation equals

• heat of fusion + heat of vaporization

• heat of deposition

• heat of vaporization + heat of freezing

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NGSS.HS-PS3-4

How much energy is needed to melt 45g of ice?

(Heat of fusion of H₂O = 6kJ/mol, heat of vaporization of H₂O = 41kJ/mol

• 6 kJ

• 15 kJ

• 135 kJ

• 270 kJ

Answer explanation

45g of ice = 2.5 mol H₂O

melting → heat of fusion

2.5 mol × 6 kJ/mol = 15 kJ

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NGSS.HS-PS3-1

What will be the Segment 1 (first step) if we want to calculate the energy change in the total conversation of 60 grams of H₂O from -25 ˚C to 70 ˚C?

• Warming the -25 C ice into 70 C directly

• Warming the H2O until it turns into Liquid

• Warming the H2O from -25 C to 0 C

• Melt it and drink it

• He's Correct

• He's wrong, he's missing the segment of melting

• He's wrong, he's missing the segment of condensation

• He's wrong, he forgets to do the vaporization

Which substance has the least specific heat capacity?

• D

• B

• C

• A

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NGSS.HS-PS3-4