Thermo Chemistry

What type of reaction is being presented in the energy profile shown?

Tags

NGSS.HS-PS1-4

What type of reaction is being presented in the energy profile shown?

Tags

NGSS.HS-PS1-4

The equation above represents the decomposition of a compound XY₂. The diagram below shows two reaction profiles (path one and path two) for the decomposition XY₂.

Which of the following best describes the flow of heat when 1.0 mol of XY₂ decomposes?

• 50 kJ of heat is transferred to the surroundings.

• 50 kJ of heat is transferred from the surroundings.

• 100 kJ of heat is transferred to the surroundings.

• 100 kJ of heat is transferred from the surroundings.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Which of the following correctly describes an exothermic reaction?

• Measured temperature of the surroundings would decrease.

• The energy of the products would be higher than the energy of the reactants

• The reaction would result in a +ΔH^o

• The reaction and resulting products would be energetically favorable.

Which of the following describes an endothermic reaction? (SELECT ALL THAT APPLY)

• The products are energetically favorable

• The ΔH^o would be positive

• The energy of the reactants is less than that of the products

• The heat flows from the system to the surroundings

Which of the following phase changes involves the transfer of heat from the surroundings to the system?

• CH_4(g) --> CH_4(l), because CH₄ molecules in the gas phase must absorb energy in order to move closer together, thereby increasing the intermolecular attractions in the solid state.

• CO_2(g) --> CO_2(s), because CO₂ molecules in the gas phase must absorb energy in order to move closer together, thereby increasing the intermolecular attractions in the liquid state.

• H₂O_(l) --> H₂O_(s), because H₂O molecules in the liquid phase must absorb energy in order to create a crystalline structure with strong intermolecular attractions in the solid state.

• NH_3(l) --> NH_3(g), because NH₃ molecules in the liquid phase must absorb energy in order to overcome their intermolecular attractions and become free gas molecules.

Tags

NGSS.HS-PS3-4

Sketch and energy profile for the following reaction:

Step 1: 3 Ag + Al(NO₃)₃ --> 3 AgNO₃ + Al (exo)

Step 2: 2 AgNO₃ --> 2 Ag + O₂ + 2 NO₂ (endo)

Step 3: 2 NO₂ --> 2 NO + O₂ (endo)

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

What strategy should Taylor use to address the thermos' problems?

• Add another insulator layer around the bottle

• Switch the inner bottle for something that has less mass.

• Get a better lid to trap the steam and hot air in.

• Add silvered surfaces around the bottle.

Tags

NGSS.HS-ETS1-3

NGSS.HS-PS3-4

Which of the following statements is true about an exothermic reaction?

• The system absorbs heat from the surroundings.

• The products have higher energy than the reactants.

• The reaction releases heat to the surroundings.

Tags

NGSS.HS-PS1-4

In a calorimetry experiment, if the temperature of the water increases, what can be inferred about the reaction?

• The reaction is endothermic.

• The reaction is exothermic.

• The reaction absorbs energy.

• The reaction does not involve heat transfer.

Tags

NGSS.HS-PS1-4