Chemistry Ch4 Discussion and Quiz Answers

How do you classify a change in a substance as physical or chemical?
A physical change: * can be observed; * is reversible; * takes place when the form (state) of the substance changes without changing its chemical composition (the change does not affect the structure).
A chemical change (reactions): * appears when one substance is transformed into another substance (which then becomes a new set of properties, thus a new substance); * can be observed (via change in color, smell, or (from the release of energy) in the form of bubbles or a change in light; * ------------------------------------------------- is irreversible (because a new substance was formed).

QUIZ ANSWERS

What is the term for the abbreviation for the name of a chemical compound that indicates the number of atoms of each element? c. chemical formula What is the term for matter having an indefinite composition and variable properties? c. heterogeneous mixture

Which of the following laws states that a compound always contains the same elements in the same proportion by mass? d. law of definite composition

Which of the following describes a substance in the liquid physical state? a. The substance has a variable shape. b. The substance has a fixed volume. c. The substance compresses negligibly. d. all of these

Which of the following chemical elements corresponds to the symbol H? c. hydrogen

Which of the following chemical elements corresponds to the symbol P? a. phosphorus

Which of the following chemical elements corresponds to the symbol Cu? a. copper Which of the following chemical symbols corresponds to argon? b. Ar

Which of the following chemical symbols corresponds to cadmium? c. Cd

Which of the following chemical symbols corresponds to krypton? b. Kr

Which of the following chemical symbols corresponds to manganese? c. Mn

Which of