New substances, like synthetic materials, are formed as the result of chemical reactions?
physical changes?
natural process in nature?

Calculate the number of kilojoules to warm 125 g of iron from 23.5°c to 78.0°c.

Which statement best describes the function of enzymes?

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride