What happens when iron filings and sulfur are mixed without heating?
They form a mixture that can be separated using a magnet.
What is a mixture?
A mixture contains two or more substances that are not chemically bonded together.
You mix sand and salt together. Is this a mixture or a compound? How can you separate them?
A mixture. You can separate them by dissolving the salt in water, filtering the sand, and evaporating the water.
If you heat sugar, it turns brown and produces smoke. Is this a physical or chemical change? Why?
Chemical change, because new substances are formed.
Give two examples of mixtures in everyday life.
Air, seawater, salad, mud, etc.
What are the main components of air?
Nitrogen (N₂), oxygen (O₂), carbon dioxide (CO₂), and other gases
Can you usually separate mixtures easily? Why?
Yes, because the substances in a mixture are not chemically bonded and can be separated by physical methods.
Is air a mixture or a compound? Why?
A mixture, because it contains different gases that are not chemically bonded.
A student says that seawater is a compound. Do you agree? Why or why not?
No, because seawater contains different substances (water, salt, minerals) that are not chemically bonded.
What is an alloy? Give an example.
An alloy is a mixture of metals. Example: Nitinol (nickel + titanium).
How is a mixture different from a compound?
A mixture consists of substances that retain their own properties, while a compound has new properties different from its individual elements.
What type of change occurs when making a salad—physical or chemical?
Physical change, because the ingredients retain their properties.