Classify each of the following as a physical change or a chemical change. melting ice: souring of milk: digesting food: evaporating water?

- melting ice is a physical change

- souring of milk is a chemical change

- digesting food is a chemical change

- evaporating water is a physical change

Explanation:

A chemical change involves formation of new product and is irreversible, while physical change may involve the formation of new products and is easily reversible.

Physical Changes are described below

- Ice on melting forms water, that can be refrigerated to yield ice again

- water on evaporation during heating yields steam that can be condensed to yield water again.

Chemical change

- souring of milk involves bacteria oxidation of chemicals in the milk that changes its composition, smell, and taste; fresh milk CANNOT be obtained again

- food digestion involves mechanical breaking by teeth, stomach walls and several enzyme actions to yield glucose, amino acids etc. It cannot be reversed to whole food again

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.