States of Matter
What are the three main states of matter?
Solid, Liquid, Gas
What tool do scientists use to measure mass?
A balance scale.
What is a physical property?
A characteristic that can be observed without changing the substance.
Why do we use metal to make pots and pans?
Because metal conducts heat well.
What is the purpose of a control group in an experiment?
It provides a comparison to see if a variable affects the results.
Which state of matter has a definite shape and volume?
Solid
What unit is used to measure the volume of a liquid?
Milliliters or liters
Give two examples of physical properties.
Color, texture, hardness, density, melting point.
Why are raincoats made of waterproof materials?
They repel water and do not absorb it.
What observation would tell you that a chemical reaction has taken place?
Change in color, temperature, bubbles, or formation of a new substance.
You pour water into a container, and it takes the shape of the container. What property does this show?
Liquids take the shape of their container.
How can you measure the volume of an irregular object, like a rock?
Use water displacement in a graduated cylinder.
How can you tell if a substance has high or low conductivity?
High conductivity allows electricity or heat to pass through easily, like metal.
Why do bridges have small gaps between sections of metal?
To allow for expansion when metal heats up.
An experiment tests how temperature affects the melting speed of ice. What is the independent variable?
The temperature.
Why does a balloon expand when heated?
The gas inside expands as particles move faster.
Which is denser, water or oil? How do you know?
Water is denser because oil floats on top of it.
What is the difference between a physical and chemical change?
A physical change does not create a new substance, but a chemical change does.
Why does salt help melt ice on the roads in winter?
It lowers the freezing point of water, causing ice to melt.
You drop a sugar cube into water. It dissolves completely. Is this a physical or chemical change? Why?
Physical change; no new substance is formed.
Explain how a solid can change into a gas without becoming a liquid first. Give an example.
Sublimation, such as dry ice turning into carbon dioxide gas.
You have a block of metal and a block of wood that are the same size. How would you use measurements to determine which is denser?
Measure mass and volume, then use the density formula: Density = Mass/Volume.
If a nail rusts, is that a physical or chemical change? Why?
Chemical change; a new substance (rust) forms, and it cannot be reversed easily.
If you had to design a new water bottle, what properties would be important for the material? Explain your choices.
Lightweight, durable, non-toxic, waterproof, and possibly insulated to keep drinks cold
You are testing which type of metal rusts the fastest in water. What measurements would you take, and how would you analyze the results?
Measure weight, surface changes, or color over time; compare how quickly rust forms on different metals.