Matter Matters!
Anything that has mass and takes up space is called what?
Matter.
-200
Ice melts. Physical or chemical change?
Physical change.
-400
Name THREE observations that could provide evidence that a chemical reaction occurred
Possible answers: bubbles/gas, color change, temperature change, formation of a solid/precipitate, state of matter change, smell, texture change, etc.
+500
True or false: Atoms disappear during a chemical reaction.
False.
+100
What does the conservation of matter tell us about atoms during a chemical reaction?
Matter is not created or destroyed. The same atoms are present before and after the reaction.
+300
What is the tiny unit of matter that makes up elements?
Atom.
+200
A piece of paper burns. Physical or chemical change?
Chemical change.
-200
A student sees bubbles when two substances are mixed. Does that automatically prove a chemical reaction happened? Why/not?
No. One piece of evidence is not a guarantee; could be a physical change. Something new must be made and permanent.
+300
True or false: New atoms are created during a chemical reaction.
False.
-200
A reaction happens inside a completely sealed container. Should the total mass change?
Ideally, no. The mass should stay the same.
+300
What do you call two or more atoms connected together?
Molecule
+300
A glass shatters into smaller pieces.
1) Did a new substance form?
2) What type of change is this?
No, it's physical change.
+300
Why is it useful for scientists to look for multiple pieces of evidence when investigating a reaction?
One observation by itself may not prove that a new substance formed. Multiple pieces of evidence give scientists stronger support for their claim.
+200
During a chemical reaction, what happens to the atoms?
They rearrange into new combinations/molecules
+300
A sealed bag has a mass of 142.6 g before a reaction and 142.5 g afterward. Did the reaction destroy 0.1 g of matter?
No. Small differences can result from measurement limitations, or inconsistencies in the setup.
+200
In a chemical reaction, what are the substances you start with called?
Reactants.
-300
You mix up some batter, place it in a pan, and bake it in the oven. A cake is made! What type of reaction is this?
Chemical
-200
What is a chemical reaction?
A process where one or more starting substances turn into different new substances; cannot be easily (or ever) undone.
-400
Before a reaction, you have four A atoms and four B atoms.
After the reaction, you have four AB molecules.
How many A atoms are there after the reaction?
4 (nothing is added or removed).
-400
Which system would make it easiest to observe conservation of matter? WHY??
A. An open cup
B. A sealed container
C. An uncovered beaker
D. A pile of powder on a table
B, a sealed cup. In an open system, it is hard to see the conservation of matter because matter can freely enter or exit the system, making it difficult to measure all the components
+500
In a chemical reaction, what are the new substances formed at the end called?
Products.
+300
Two clear liquids are mixed. A cloudy solid suddenly appears. What type of change is this most likely?
Chemical.
-300
Two clear liquids are mixed. The mixture becomes cloudy, a solid forms, the temperature changes, and the color changes. Would you have strong evidence that a chemical reaction occurred? Explain.
Yes. Multiple observations suggest that new substances may have formed.
-300
Consider this reaction:
A–A–A–A + B–B–B–B → A–B + A–B + A–B + A–B
Did the atoms disappear? What happened instead?
No. The atoms were rearranged into new combinations. The same A and B atoms are still present.
-300
A student says, “The mass decreased because the reaction created gas, and gas doesn't have mass.”
Is the student correct? Explain.
No. Gas has mass. If gas escapes from an open system, the measured mass can decrease because some matter left the system.
-300