Chapter 1, Problem 21c
Label each of the following as either a physical process or a chemical process: (c) melting a piece of chocolate
Video transcript
(a) Read the following description of the element zinc and indicate which are physical properties and which are chemical properties. Zinc melts at 420 °C. When zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. Zinc has a hardness on the Mohs scale of 2.5 and a density of 7.13 g/cm3 at 25 °C. It reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, ZnO.
(b) Which properties of zinc can you describe from the photo? Are these physical or chemical properties?
Label each of the following as either a physical process or a chemical process: (b) production of urine in the kidneys
A match is lit and held under a cold piece of metal. The following observations are made: (a) The match burns. (b) The metal gets warmer. (c) Water condenses on the metal. (d) Soot (carbon) is deposited on the metal. Which of these occurrences are due to physical changes, and which are due to chemical changes?
A silvery metal is put inside a beaker of water. Bubbles form on the surface of the metal and it dissolves gradually. (a) Is this an example of a chemical or a physical change?
(a) Calculate the kinetic energy, in joules, of a 15-g bullet moving at 120 m/s.