recognizing chemical reactions
examples of chemical reactions
Look carefully at the Figures 1.1, 1.2, and 1.3. All of the photos demonstrate chemical reactions. For each photo, identify a sign that one or more chemical reactions have taken place. A burning campfire can warm you up on a cold day. Dissolving an antacid tablet in water produces a fizzy drink. Adding acid to milk produces solid curds of cottage cheese. Q: Did you ever make a volcano by pouring vinegar over a mountain of baking soda? If you did, you probably saw the mixture bubble up and foam over. Did a chemical reaction occur? How do you know? A: Yes, a chemical reaction occurred. You know because the bubbles are evidence that a gas has been produced and production of a gas is a sign of a chemical reaction.
whats your sign
A change in color is just one of several potential signs that a chemical reaction has occurred. Other potential signs include: Change in temperature-Heat is released or absorbed during the reaction. Production of a gas-Gas bubbles are released during the reaction. Production of a solid-A solid settles out of a liquid solution. The solid is called a precipitate. Click image to the left or use the URL below. URL:
No diagram descriptions associated with this lesson
all changes in matter are the result of chemical reactions.
a. true --> b. false
signs that a chemical reaction has occurred include a change in
a) temperature. b) color. c) state. --> d) two of the above
which of the following is a sign of a chemical reaction?
a) a liquid changes to a solid. b) a liquid changes to a gas. c) a solid changes to a gas. --> d) a gas is released from a liquid.
the solid lumps in cottage cheese are an example of a precipitate.
--> a. true b. false
the release of gas bubbles is a sign of a chemical reaction.
--> a. true b. false
which of the following does not involve chemical reactions?
a) leaves change color in the fall. --> b) a pond freezes over in the winter. c) a fire burns a pile of fallen leaves. d) fallen leaves decay in a compost pile.
No diagram questions associated with this lesson