Thermochemistry-1&2

(Work)

Any work done by the system uses energy.

• positive

• negative

• zero

• indefinite

(Heat)

Decrease in temperature of the system

• positive

• negative

• zero

• indefinite

(Heat)

System absorbs heat due to work being done by its surroundings.

• positive

• negative

• zero

• indefinite

1. (Work) Work done by the surroundings on the system.

2. (Heat) Heat enters the surroundings from the system.

• 1. W - negative

  2. H - positive

• 1. W - negative

  2. H - negative

• 1. W - positive

  2. H - positive

• 1. W - positive

  2. H - negative

1. (Heat) When the heat is released to the surroundings

2. (Work) Work done by the system to the surroundings.

• 1. H - negative

  2. W - positive

• 1. H - negative

  2. W - negative

• 1. H - positive

  2. W - positive

• 1. H - positive

  2. W - negative

Statement A: The system loses 726 J to the surroundings as heat.

The enthalpy change for the system is positive.  

Statement B: The system absorbs 178 J to the surroundings as heat.

According to sign conventions heat is negative. 

 

• Both statements are correct. 

• Both statements are incorrect. 

• Statement A is correct, Statement B is incorrect. 

• Statement A is incorrect, Statement B is correct. 

Identify the process involved:

Combustion of fuels such as wood, coal and oil/petroleum.

• Exothermic

• Endothermic

• No heat exchange

Identify the process involved:

Melting of Ice

• Exothermic

• Endothermic

• No heat exchange

Identify the process involved:

(1) Photosynthesis

(2) Explosion of bombs

• (1) Exothermic

  (2) Endothermic

• (1) Exothermic

  (2) Exothermic

• (1) Endothermic

  (2) Exothermic

• (1) Endothermic

  (2) Endothermic

Identify the process involved:

(1) Evaporation of Water

(2) Freezing of Water

• (1) Exothermic

  (2) Endothermic

• (1) Endothermic

  (2) Endothermic

• (1) Exothermic

  (2) Exothermic

• (1) Endothermic

  (2) Exothermic