Whether a Change Is Physical Or Chemical Can Be Difficult

DETERMINING WHETHER A CHANGE IS PHYSICAL OR CHEMICAL CAN BE DIFFICULT 

Potassium chromate changes color as its temperature changes. This change in color is a physical change. A return to the original temperature restores the original bright yellow color. 

When heated, orange ammonium dichromate undergoes a chemical change to ammonia, water vapor, and chromium (III) oxide. A return to the original temperature does not restore the orange color because the ammonium dichromate is no longer there. 

Michaela has grown an inch in height over the past year. Is this best described as a physical or a chemical change  

Was this your answer Are new materials being formed as Michaela grows Absolutely—created out of the food she eats. Her body is very different from, say, the peanut butter sandwich she ate yesterday. Yet through some very advanced chemistry, her body is able to take the atoms of that peanut butter sandwich and rearrange them into new materials. Biological growth, therefore, is best described as a chemical change. 

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