Energy in Chemical Reactions

Energy Transformation in Chemical Reactions

• Chemical reactions transform stored energy into other forms.

• Energy can be released (exothermic) or absorbed (endothermic):

  • Exothermic: Reactants have higher potential energy than products, releasing energy.

  • Endothermic: Reactants have lower potential energy than products, absorbing energy.

Energy in Biological Processes

• Cellular respiration converts glucose and oxygen into carbon dioxide, water, and energy.

• Overall reaction: $C<em>6H</em>{12}O<em>6 + 6O</em>2 \rightarrow 6CO<em>2 + 6H</em>2O + \text{energy}$

• Energy is stored as ATP, utilized for various cellular activities.

Photosynthesis

• Photosynthesis: Converts CO2 and H2O into glucose and O2 using light energy.

• Overall reaction: $6CO<em>2 + 6H</em>2O + \text{light energy} \rightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2$

• Occurs in chloroplasts; involves light-dependent and light-independent reactions.

Fossil Fuels

• Fossil fuels (coal, oil, natural gas) originate from ancient plants' chemical potential energy.

• Burning fossil fuels releases energy and carbon dioxide, contributing to climate change.

Fuel Cells

• Fuel cells transform chemical potential energy into electrical energy efficiently, producing only water as a byproduct:

  • Reaction: $2H<em>2(g) + O</em>2(g) \rightarrow 2H_2O(g) + \text{energy}$

• Considered cleaner technology compared to combustion of fossil fuels.