Question

A tree grows and increases its mass. Explain why this phenomenon is not a violation of the law of conservation of matter.

Short answer

The tree's growth incorporates existing matter, not creating it, thus conserving matter.

Step-by-step solution

Understanding the Phenomenon

Trees grow by incorporating different substances from their environment into their structure. Primarily, they absorb carbon dioxide from the air and water from the soil, and through the process of photosynthesis, they convert these into glucose and other organic compounds, which add to the tree's mass.

Law of Conservation of Matter

The law of conservation of matter states that matter cannot be created or destroyed in an isolated system. This implies that the tree's increase in mass must come from outside sources rather than being magically 'created' by the tree itself.

Source of Increased Mass

The increase in the tree's mass is due to the matter absorbed from the environment: carbon from carbon dioxide in the air and hydrogen and oxygen from water taken up by the roots. These elements are rearranged to form new compounds within the tree, which adds to its mass.

Photosynthesis

During photosynthesis, sunlight energy is used to convert carbon dioxide and water into glucose and oxygen. The chemical equation is: \[ 6 ext{CO}_2 + 6 ext{H}_2 ext{O} + ext{light energy} ightarrow ext{C}_6 ext{H}_{12} ext{O}_6 + 6 ext{O}_2 \] Here, the elements are conserved and rearranged, supporting the law of conservation of matter.

Conclusion

Since the tree derives its increased mass from molecules already existing in its environment, it does not violate the law of conservation of matter. These elements are converted and stored as part of the tree's biomass.

Key concepts

Photosynthesis

Photosynthesis is a vital process for plants, allowing them to convert light energy into chemical energy. This process occurs in the chloroplasts of plant cells. It involves absorbing sunlight, water, and carbon dioxide to produce glucose and oxygen.

The main purpose of photosynthesis is to provide energy for the plant, which is stored in the form of glucose. This glucose can later be used as a source of energy during cellular respiration, or it can be converted into cellulose to contribute to the structure and growth of the plant. Here's how it works:

• Carbon dioxide enters the leaves through small pores called stomata.
• Water is absorbed through the roots and transported to the leaves.
• Sunlight, absorbed by chlorophyll, provides the energy needed for the reaction.

Through the equation \[ 6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2 \]we can see how the reactants are transformed into new compounds. This indicates the conservation of matter, as the input molecules are simply rearranged to form new substances.

Tree Growth

Tree growth largely depends on the conversion of environmental molecules into biomass, thanks to the photosynthetic process. The increase in mass is mainly due to the accumulation of organic compounds, formed when trees convert atmospheric carbon dioxide and water into glucose.

The tree utilizes this glucose in several ways:

• As an energy source for growth and maintenance through cellular respiration.
• As a building material, converting glucose into cellulose for its cell walls.
• As a storage compound in the form of starch.

By storing these organic compounds, trees increase in size, demonstrating visible growth. The matter itself comes from the transformation and storage of existing elements in the environment, ensuring compliance with the law of conservation of matter. The glucose and other stored carbohydrates act as building blocks, allowing the tree to develop sturdy structures like trunks and branches over time.

Environmental Chemistry

Environmental chemistry focuses on the chemical processes occurring in natural systems, like forests. It examines how different elements and compounds interact in these systems.

In the case of tree growth, environmental chemistry provides insight into how matter is conserved and transformed in ecosystems. The law of conservation of matter is a key principle, emphasizing that all matter - including that absorbed by trees - is neither created nor destroyed, but merely changes forms.

Key aspects include:

• The cycling of elements, where carbon and water taken in by trees are continuously recycled.
• The conversion of inorganic substances into organic matter, which is essential for sustaining living organisms.
• The role of sunlight as the driving force behind photosynthesis.

This chemistry helps explain not only how trees grow, but also how they affect and are affected by their surroundings. By understanding how photosynthesis and other chemical interactions support tree growth, we can better appreciate the delicate balance of natural ecosystems.