Evidence of a chemical reactions is anything that shows -
a new substance has formed
a solid dissolved in a liquid
interaction between 2 gases
a change in the state of matter
2. Multiple Choice
1 minute
1 pt
One of the signs of a chemical reaction taking place is:
Bubbles are produced
Reactants are not combining
Products are not forming
Color is not changing
3. Multiple Choice
1 minute
1 pt
Which of the following describes a precipitate?
a liquid forms when a block of metal is heated
a solid forms when one liquid is poured into another
a gas forms when a solid is placed in a liquid
bubbles form when an acid is poured on a rock
4. Multiple Choice
1 minute
1 pt
Which is NOT an indication of a chemical change?
temperature change
formation of a precipitate
shape change
production of light
5. Multiple Choice
1 minute
1 pt
You know you a chemical reaction has occurred if
there is a precipitate.
there is a color change.
there is a temperature change.
All of these answers are evidence.
6. Multiple Choice
20 seconds
1 pt
A clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?
The level of the substance in the beaker is higher after the other liquid is added.
A yellow solid forms and then settles to the bottom of the beaker.
Small white crystals are left behind in the flask that held the first liquid.
The mass of the combined liquids is greater than either original liquid.
7. Multiple Choice
1 minute
1 pt
Which of the following is an example that includes evidence of a chemical reaction?
A sample of zinc is placed in water and it settles to the bottom
A solid block of ice is heated and it completely melts into a liquid.
Sugar that is burned gives off an odor and turns brown and then black.
A tomato is placed into a blender and chopped up into smaller pieces.
8. Multiple Choice
45 seconds
1 pt
Four students performed four different investigations by combining different substances. Which of the observations is most indicative of a chemical reaction?
investigation 1
investigation 2
investigation 3
investigation 4
9. Multiple Choice
1 minute
1 pt
A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles -
could show that a gas is forming.
always rise to the top of a liquid.
are almost always perfectly spherical.
usually burst after a few minutes.
10. Multiple Choice
45 seconds
1 pt
In a container, a solid consisting of clear crystals is combined with a blue liquid and the following observations are obtained: How many of the listed observations indicate a new substance was formed?