Scientific Method
A scientist changes the amount of sunlight a plant gets, what variable is being changed?
Independent Variable
What is the formula for density?
Density = Mass/Volume
Tearing paper
Physical
Matter is anything that has... and...
Mass and Volume
All chemical changes are impossible to reverse.
False
What is the first step of the scientific method?
Observe/Ask a question
An object has a mass of 24g and volume of 6 mL
4g/ml
Rust forming on a bike
Chemical
Is color a physical or chemical property?
Phys
A student says, "If something floats, it has no mass."
Is this correct?
No, it's less dense that the liquid.
A student says,
"My plant grew because I talked to it every day."
Question: What additional information would you need before accepting this conclusion?
Need more
An object has a density of 0.8 g/mL
Will it sink or float in water?
Float
Salt being left on noodles, from water boiling out
Physical
Is flammability a phys or chem property?
Chem
Which has more density?
A pound of feathers or a pound of rocks?
Rocks
Why do scientist repeat experiments
To make sure data is relaible
Two objects have the same size, but one is much heavier.
Which is more dense
The heavier one
A student burns a marshmallow until it turns black.
Identify three pieces of evidence that a chemical change occurred.
Color change, new smell, smoke/gass produced, New substance (char), Can not easily be reversed
A student says: "Density is a physical property because you can measure it without changing what the substance is."
Do you agree? Explain.
Yes. Measuring density does not create a new substance, so it is a physical property.
A student places an ice cube into a cup completely filled with water.
When the ice melts...
A. Water spills over the cup.
B. The water level stays the same.
C. The water level decreases.
Answer: B. The water level stays the same because floating ice already displaces an amount of water equal to its weight.
Used steps
A boat made of steel floats, but steel marble sinks.
Explain using Density.
Boat has air, density less than water will float
Marble steel is greater than water, will sink
Explain which is a phys/chem?
Wax melting
Wax burning
Wax melting, chemical change of state
Wick burning = Chemical (new substances like smoke and ask form)
You have three identical cubes.
Cube A: Sinks immediately
Cube B: Floats
Cube C: Stays suspended in the middle of the water.
Rank them from greatest to least density and explain
Cube A (greatest)
Cube B (about the same density as water)
Cube (least)
Scientists discover a mystery liquid.
Question: List all the physical properties described and calculate its density.