Which of the following gives off more energy than it absorbs? melting ice, burning propane in a gas heater, sublimation of carbon dioxide to carbon dioxide gas, recharging a car battery

I am thinking burning propane in a gas heater. It give off energy.

The others seem to be absorbing energy.

recharging a battery

Recharge a battery

To determine which of the given options gives off more energy than it absorbs, we need to analyze each process individually.

1. Melting ice: When ice is melted, it absorbs energy from its surroundings to overcome the energy required to break the intermolecular forces holding the water molecules together. Therefore, melting ice absorbs energy rather than giving off more energy.

2. Burning propane in a gas heater: During the combustion of propane, a chemical reaction occurs where propane reacts with oxygen to produce carbon dioxide and water vapor. This reaction releases energy in the form of heat and light. Thus, burning propane in a gas heater gives off more energy than it absorbs.

3. Sublimation of carbon dioxide to carbon dioxide gas: Sublimation is the phase transition in which a substance goes from a solid directly to a gas, bypassing the liquid phase. When carbon dioxide undergoes sublimation, it absorbs energy from its surroundings to break the intermolecular forces and transition from a solid to a gas. Therefore, sublimation of carbon dioxide absorbs energy rather than giving off more energy.

4. Recharging a car battery: When recharging a car battery, an electrical current is passed through it, causing a reaction where lead sulfate is converted back to lead dioxide and lead. This process requires the input of electrical energy from an external power source, such as an electric charger. Hence, recharging a car battery absorbs energy rather than giving off more energy.

In conclusion, the only option that gives off more energy than it absorbs is burning propane in a gas heater.