Experiments
Monica is testing out two new cookie recipes and asks her friends to help her decide which one is better. She bakes a batch of each and serves them to Joey, Rachel, and Ross. Joey says, “These cookies are super soft and smell amazing!” Rachel says, “I like the second batch better—it’s sweeter.” Ross uses a scale and says, “Each cookie from the first batch weighs exactly 25 grams.”
Who made a qualitative observation?
Joey and Rachel
Monica stores leftover soup in the freezer, and it becomes hard and keeps its shape.
What state of matter is the soup now?
Solid
Ross wants to know what number 3 represents on the phase diagram?
Gas
Joey weighs a meatball and says it’s 150 grams.
What type of property is this? (Hint: not physical or chemical)
Extensive Property
Ross shows a diagram of two oxygen atoms bonded together.
What is he showing?
Rachel wants to prove she can make better coffee than Gunther. She brews three different batches: One with her usual method, One using Gunther’s recipe, One using a fancy French press. She serves each batch to Joey, Monica, and Chandler without telling them which is which. They rate the taste on a scale from 1 to 10. All batches use the same coffee beans, water temperature, and serving cups.
What is the independent variable?
Coffee brewing method
Ross explains that lightning is an example of what high-energy state of matter?
Plasma
Chandler wants to make a joke about a critical point but needs to know the definition of it first before he can make one.
Point beyond which a gas cannot be liquified by pressure alone.
Monica describes her cookie dough as soft, sweet-smelling, and beige in color.
What type of property is this?
Physical Property
Monica combines hydrogen and oxygen to make water in a cooking experiment.
What did she create?
Ross wants to know if the type of dinosaur trivia affects how well his students remember facts. He uses three trivia formats: flashcards, videos, and games.
What is the dependent variable?
How well his students remember facts
Monica boils water for pasta and sees steam rising.
What phase change is this?
Vaporization
At a constant temperature, how would Joey go from a gas to a liquid?
Increase pressure
Phoebe mixes two potions and they bubble and change color.
What type of property is this?
Chemical Property
Phoebe says, “This perfume is made of molecules that are chemically bonded together and can’t be separated physically.”
What is the term for this?
Chemical substance
Chandler is timing how long it takes for his sarcastic comments to get a laugh, but sometimes he forgets to start the stopwatch right away.
What type of experimental error is this?
Random error
Phoebe sees frost forming on the window as the temperature drops.
What phase change is this?
Deposition
Phoebe wants to know where she should look to find the melting point of this substance?
Point D (or C)
Joey cuts a sandwich in half to share with Ross.
What type of change is this?
Physical change
Joey mixes chocolate chips, marshmallows, and pretzels in a bowl and says, “This is the ultimate snack mix!”
What type of mixture did he make?
Heterogeneous
Joey thinks eating pizza before an audition helps him do better. He wants to prove it scientifically.
What steps should Joey take to prove this?
Chandler watches his iced coffee melt on the counter.
What type of heat transfer is this?
Endothermic
Rachel wants to know between which letters are there changes in potential energy?
B-C and D-E
Rachel forgot to put the milk away at Central Perk and when she showed up the next day, the milk had soured and made the entire coffee shop smell.
What type of change is this?
Chemical change
Rachel stirs sugar into her iced tea until it completely dissolves and looks the same throughout.
What type of mixture is this?
Homogenous