Unit 8 AP Chemistry

Is the phase change representing an exothermic or endothermic reaction?

• Endothermic

• Exothermic

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Is the reaction exothermic or endothermic? H2 + S + O2 -> H2SO4 ΔH = -811.13kJ

• ΔH is negative so it is exothermic

• ΔH is positive so it is exothermic

• ΔH is positive so it is endothermic

• ΔH is negative so it is endothermic

Tags

NGSS.HS-PS1-4

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

NGSS.HS-PS3-1

NGSS.HS-PS3-4

Using the equations below: C(s) + O₂(g) → CO₂(g) ∆H = –390 kJ Mn(s) + O₂(g) → MnO₂(s) ∆H = –520 kJ what is ∆H (in kJ) for the following reaction? MnO₂(s) + C(s) → Mn_(s) + CO₂(g)

• 910

• 130

• -130

• -910

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Using the equations below Cu(s) + 1/2O2(g) → CuO(s) ∆H = –156 kJ 2Cu(s) + O2(g) → Cu2O(s) ∆H = –170 kJ what is the value of ∆H (in kJ) for the following reaction? 2CuO(s) → Cu2O(s) + 1/2O2(g)

• 142

• 15

• -15

• -142

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Which of these processes represents a decrease in entropy?

• sublimation of CO₂

• boiling water

• condensation of steam on cold glass

• NaCl dissolving in water

Which of these reactions shows a DECREASE in entropy?

• CaCO₃(s) → CaO(s) + CO₂(g)

• 3O₂(g) → 2O₃(g)

• 2NH₃(g) → 3H₂(g) + N₂(g)

• C₆H₆(l) → C₆H₆(g)

A reaction has a positive ΔH and a positive ΔS. Which of the following is true?

• It will be spontaneous at all temperatures.

• It will be nonspontaneous at all temperatures.

• It will be spontaneous at low temperatures.

• It will be spontaneous at high temperatures.

Your enthalpy is high and negative but your entropy is also negative. What type of temperature would you want to get a spontaneous reaction?

• low

• high

True/False: The rate of a chemical reaction is unrelated to the spontaneity of the reaction.

• True

• False

Tags

NGSS.HS-PS1-5