Nutrition and Growth of Bacteria (page 4) (This chapter has 6 pages) Â© Kenneth Todar, PhD Physical and Environmental Requirements for Microbial Growth The procaryotes exist in nature under an enormous range of physical conditions such as O2 concentration, Hydrogen ion concentration (pH) and temperature.
In a double replacement reaction parts of two compounds switch places to form two new compounds. Two reactants yield two products. For example when silver nitrate combines with sodium chloride, two new compounds--silver chloride and sodium nitrate are formed because the sodium and silver switched places.
When you have finished this page, try the Chemical and Physical Changes Quiz. There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is.In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed. For example, if a piece of paper is cut up into small pieces it still is paper.hen heat is given off in a chemical change or reaction, it is called an exothermic reaction. When heat is absorbed in a chemical change or reaction, it is called an endothermic reaction.