Key Concepts
What are molecules?
Molecules are groups of two or more atoms that are chemically bonded together. They are the smallest units of a substance that retain its chemical properties.
Why did the food coloring separate into different dyes?
Food coloring may contain multiple dyes with different solubility levels.
What happens when two substances are mixed together?
They may form a solution, a suspension, or a heterogeneous mixture, depending on the nature of the substances and their molecular interactions.
How can we determine if a solid will dissolve in water?
By testing the solid in water to see if it disperses or disappears, forming a clear solution.
What is a homogeneous mixture?
A homogeneous mixture is a mixture where the components are evenly distributed, and it looks uniform throughout, such as a solution of salt in water.
How do the properties of a substance relate to its molecules?
The properties of a substance are determined by the types of molecules it contains and how these molecules interact with each other.
Why do some salad dressings have sediments, and others do not?
Some dressings have particles (like herbs or spices) that do not dissolve completely and settle at the bottom, while others are fully emulsified or consist of ingredients that dissolve or stay suspended evenly.
Can all liquids mix together? Why or why not?
No, not all liquids mix together. Some, like oil and water, do not mix due to differences in molecular structure.
What are the differences between different types of molecules?
Molecules can differ in size, shape, charge, polarity, and the types of atoms they contain, influencing their interactions and properties.
What is a heterogeneous mixture?
A heterogeneous mixture is a mixture where the components are not evenly distributed and can be seen as distinct parts, such as oil and vinegar.
What happens to some solids when they are mixed with water?
Some solids dissolve, breaking down into their individual molecules which spread evenly throughout. Others do not dissolve and may stay as sediments.
Why can salad-dressing ingredients separate again after being mixed?
Salad-dressing ingredients like oil and vinegar separate because they do not dissolve in each other and have different densities. Without an emulsifier, the molecules of each liquid prefer to group together
What does it mean for a mixture to separate into layers?
It means the substances in the mixture do not stay evenly distributed and instead settle into distinct layers based on differences in density or solubility.
How does the attraction between different molecules affect their behavior?
Stronger attractions lead to substances being more cohesive (sticking together) or adhesive (sticking to other materials).
How can you tell if a liquid mixture will stay mixed over time?
If the mixture remains uniform and does not separate into layers or particles over time, it is likely stable. The presence of an emulsifier can also help maintain the mixture.
Why do some liquids hold together more than others?
Some liquids have stronger molecular attractions which makes them more likely to hold together and resist spreading.
What happens to the molecules of a solid when they dissolve in a liquid?
The molecules or ions of the solid break apart and spread evenly throughout the liquid, creating a homogeneous mixture (solution).
What do we add to help bond two liquids?
Emulsifier: Letichen
What is an emulsifier and how does it work?
An emulsifier is a substance that helps mix liquids that usually don’t mix, such as oil and water. It works by having one part of the molecule attracted to another part allowing the liquids to stay blended.
How do different types of salad dressings demonstrate the properties of mixtures?
Salad dressings demonstrate properties of mixtures like emulsions (blended oil and water), suspensions (particles that settle out), and solutions (dissolved substances).