Science Homework: Research Physical and Chemical Changes that occur in nature. Describe two examples for each (3-4 sentences each) DUE: Thursday 5th February
Many changes occur in our natural environment, both physical and chemical. Physical changes occur when a substance changes from one state (gas, liquid, solid) to another without alteration of the chemical composition. Contrary to chemical changes, physical changes are mostly reversible. Chemical changes take place when new chemical substances are formed. Some of the physical changes in nature include erosion, magma hardening after cooling and also leaves falling off trees. Erosion is proved to be a physical change as the chemical properties are not changed. When erosion occurs, it is simply breaking down a large part of nature into smaller pieces. For example, when we break take a rock from a mountain and throw it somewhere else, we are contributing to part of the erosion of the mountain. Smaller pieces are made as the rock may hit the ground and cracked, making little pieces of rock. When leaves fall of trees, it is also a physical change as the leaf is simply moving from being a part of a tree to a solitary leaf on the ground. Both the chemical composition and state are not altered. On the contrary, the changing of colour on leaves is a chemical change as a new colour is created and the change is irreversible. In autumn, many deciduous trees’ leaves change colour as their nutrients begin to drain into the branches, roots and trunk of the tree. This is a chemical change to prepare the tree for winter. This is done by stopping the production of the green pigment chlorophyll. Leaves changing colour is a clear example of a chemical change taking place in nature, along with wood burning in a forest fire and photosynthesis. When wood burns in a fire, a chemical reaction occurs causing the heat and oxygen to transform the wood into carbon dioxide, water vapour and ash. In this case, wood has converted into...
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