Properties of Matter
A student mixes 100 g of water with 20 g of sugar. What should the mixture weigh?
120 g
Which state of matter has particles that spread out to fill all the space available?
Gas
When baking soda is added to an acidic liquid, what is one thing you might observe?
Bubbling / Fizzing
In a fair test, should you change one variable or many variables at the same time?
One variable
What is one sign that a chemical reaction may have happened?
Gas/bubbles, temperature change, color change, new substances being created (think slime being made out of glue and borax)
Water is frozen into an ice cube. Has the amount of matter changed?
No; it is still the same amount of matter, it has just changes state.
Compared with particles in a liquid, how are particles in a gas arranged?
They are much farther apart and can move throughout the container.
You test orange juice and water with baking soda. Orange juice fizzes but water does not. Which liquid is more likely acidic?
Orange juice.
Two students want to test whether the amount of baking soda changes a reaction. What should they keep the same?
The amount/type of other substances and other testing conditions.
Baking soda and vinegar are mixed and bubbles immediately form. What do the bubbles provide evidence of?
A gas was produced during a chemical reaction.
A sealed container weighs 250 g before two substances are mixed. After they react, what should the sealed container weigh?
250 g; the container is sealed (matter can not escape), and matter can not be created or destroyed, therefore it should weigh the exact same after a reaction.
Baking soda and vinegar react inside a sealed plastic bag and the bag expands. What are the invisible particles doing?
Gas particles are spreading out and pushing against the bag.
Three liquids are tested with equal amounts of baking soda. Liquid A has a lot of bubbles, liquid B has no bubbles, and liquid C has some bubbles. Which liquids show evidence of being acidic?
A and C
A student mixes vinegar with one spoon of baking soda and then vinegar with three spoons of cornstarch. Is this a fair test of which solid reacts with more vinegar? Why or why not?
No; different amounts of the solids were used.
A student mixes two clear liquids. The mixture becomes cloudy and a solid appears. What evidence suggests a chemical reaction occurred?
A new solid substance formed.
A cup contains 150 g of juice and 25 g of dissolved sugar. It is frozen into a popsicle. What should the popsicle weigh if none is spilled? Explain your answer.
175 g, freezing changes the state, not the amount of matter.
A ballon placed over a bottle gets larger after two substances react inside the bottle. Describe how the particles inside the balloon should be shown.
Many gas particles spread far apart throughout the balloon.
A mystery liquid fizzes strongly with baking soda. Can you conclude exactly what the liquid is? Explain.
No. You can infer it may be acidic, but many different acids can react with baking soda.
You want to find out whether baking soda or cornstarch react more with vinegar. Describe a fair test.
Use equal amounts of each solid in separate containers, at equal amounts of the same vinegar, keep all other conditions the same, and compare the reactions.
After a reaction in an open container, the materials left behind weigh less than they did before. Does this mean matter disappeared?
No. A gas may have formed and escaped into the air.
A sealed bag contains 50 g of vinegar and 10 g of baking soda. They react and the bag fills with gas. Predict the total mass after the reaction and defend your answer. Assume the bag does not explode.
60 g; matter is conserved because the gas remains inside the sealed system.
A student says, "The bag gets bigger because new matter appears when the baking soda and vinegar react." Use a particle model to correct the student.
Matter does not appear from nowhere; particles from the starting substance rearrange into new substances, including gas particles that spread out and expand the bag.
Four mystery liquids are tested with baking soda. A and B fizz, while C and D do not. What can you conclude, and what can you not conclude from this test alone?
and B show evidence of acidic properties; You cannot identify exactly what each liquid is from the test alone.
A scientist wants to discover which of 4 powders reacts with hydrogen peroxide. Design an experiment that would give trustworthy results.
Test each powder separately with the same amount/concentration of hydrogen peroxide, use equal amounts of each powder, keep the container and conditions the same, observe the same evidence of reaction, and repeat trials if possible.
Two substances are mixed in a sealed bag. The bag gets colder, bubbles form, and the bag expands. Give 2 pieces of evidence that a chemical reaction occurred and explain why the bag expands.
Temperature change and gas bubbles are evidence; newly formed gas particles spread throughout the bag and push outward.