Substances vs. Mixtures
What is a substance?
A substance is made of only one type of material (atoms or molecules) all the way through.
What is the melting point of a substance?
The temperature at which a solid substance starts to become a liquid.
Two or more substances combine to form new substances with different properties from the starting materials
What happens during a chemical reaction?
What happens to atoms during a phase change?
Atoms do not combine in new ways; they stay the same.
Can atoms be created or destroyed in a chemical reaction?
No, atoms cannot be created or destroyed.
Made of more than one substance or more than one type of atom or molecule.
What is a mixture?
What property measures how well a substance can dissolve in another?
Solubility.
What are the substances you start with in a chemical reaction called?
Reactants.
True or False: A phase change creates a new substance.
False. A phase change does not create new substances.
In a chemical reaction, what stays the same even though new substances are formed?
The number of atoms stays the same.
True or False: The properties of a substance depend on how much of it you have.
False. The properties of a given substance are the same regardless of the amount of the substance.
A property that describes how resistant a material is to being scratched or deformed.
What is hardness?
What are the substances produced by a chemical reaction called?
Products.
What is the term for a solid turning into a liquid?
Melting.
What law explains why the mass of the reactants equals the mass of the products in a chemical reaction?
he Law of Conservation of Mass.
Which of the following is a mixture: saltwater or pure gold?
Saltwater is a mixture, while pure gold is a substance
Ms. Rhinehart's first name
Who is Anita?
In a burning reaction, which two substances are produced?
Water and carbon dioxide.
What is it called when a liquid becomes a gas?
Evaporation.
True or False: The total mass changes in a chemical reaction.
False. Mass is conserved in a chemical reaction.
What characteristic can help you identify whether something is a substance or a mixture?
If it contains only one type of atom or molecule all the way through, it’s a substance. If it contains more than one type of atom or molecule, it’s a mixture.
Name two properties that do not change, regardless of the amount of substance you have.
Hardness and melting point etc..
What is the difference between a chemical reaction and mixing substances?
In a chemical reaction, atoms combine in new ways to form new substances, while in mixing, no new substances are formed.
Why is dissolving sugar in water not considered a chemical reaction?
Because no new substance is formed; the sugar molecules are just dispersed in the water.
In what type of reaction is mass always conserved?
In all chemical reactions, mass is always conserved.