1. Chapter 2 Matter and Change . 2.2 Mixtures 2.1 Properties of Matter
2.3 Elements and Compounds
2.4 Chemical Reactions
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2. Why aren't there coffee grounds in a cup of coffee?
CHEMISTRY & YOU
Why aren't there coffee grounds in a cup of coffee?
Coffee is often brewed by mixing hot water with ground coffee beans.
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3. How can mixtures be classified?
Classifying Mixtures
Describing Matter
How can mixtures be classified?
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4. So, each salad mixture has different types and amounts of components.
Describing Matter
A salad bar provides a range of items, such as lettuce, tomatoes, cheese, and green peppers.
Customers choose which items to use in their salads and how much of each item to use.
So, each salad mixture has different types and amounts of components.
A mixture is a physical blend of two or more components.
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5. Most samples of matter are mixtures.
Describing Matter
Most samples of matter are mixtures.
Some mixtures are easier to recognize than others.
You can easily recognize chicken noodle soup as a mixture of chicken, noodles, and broth.
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6. Recognizing air as a mixture of gases is more difficult.
Describing Matter
Recognizing air as a mixture of gases is more difficult.
But the fact that air can be drier or more humid shows that the amount of one component of air—water vapor—can vary.
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7. Describing Matter
Based on the distribution of their components, mixtures can be classified as heterogeneous mixtures or homogeneous mixtures.
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8. Heterogeneous Mixtures
Describing Matter
Heterogeneous Mixtures
In chicken noodle soup, the ingredients in the soup are not evenly distributed throughout the mixture.
There is likely to be different amounts of chicken and noodles in each spoonful.
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9. Heterogeneous Mixtures
Describing Matter
Heterogeneous Mixtures
A mixture in which the composition is not uniform throughout is a heterogeneous mixture.
Example: Soil
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10. Describing Matter
Homogeneous Mixtures
The substances in the olive oil are evenly distributed throughout the mixture.
So, olive oil doesn’t look like a mixture.
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11. The same is true for vinegar.
Describing Matter
Homogeneous Mixtures
The same is true for vinegar.
Vinegar is a mixture of water and acetic acid, which dissolves in the water.
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12. Olive oil and vinegar are homogeneous mixtures.
Describing Matter
Homogeneous Mixtures
Olive oil and vinegar are homogeneous mixtures.
A homogeneous mixture is a mixture in which the composition is uniform throughout.
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13. Olive oil and vinegar are homogeneous mixtures.
Describing Matter
Homogeneous Mixtures
Olive oil and vinegar are homogeneous mixtures.
A homogeneous mixture is a mixture in which the composition is uniform throughout.
Another name for a homogeneous mixture is a solution.
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14. A solution is a mixture of two or more substances in a single phase.
At least two substances must be mixed in order to have a solution.
The substance in the smallest amount and the one that dissolves or disperses is called the SOLUTE.
The substance in the larger amount is called the SOLVENT. In most common instances water is the solvent.
The gases, liquids, or solids dissolved in water are the solutes.
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15. Types of Solutions
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16. Many solutions are liquids.
Describing Matter
Homogeneous Mixtures
Many solutions are liquids.
But some are gases, like air.
And some are solids, like stainless steel, which is a mixture of iron, chromium, and nickel.
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17. Describing Matter
Homogeneous Mixtures
The term phase is used to describe any part of a sample with uniform composition and properties.
By definition, a homogeneous mixture consists of a single phase.
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18. A heterogeneous mixture consists of two or more phases.
Describing Matter
A heterogeneous mixture consists of two or more phases.
When oil and vinegar are mixed, they form a heterogeneous mixture with two layers, or phases.
The oil phase floats on the water, or vinegar, phase.
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19. At the beach, you realize that both ocean water and sand are mixtures
At the beach, you realize that both ocean water and sand are mixtures. Which is a homogeneous mixture (or solution)? Which is a heterogeneous mixture?
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20. At the beach, you realize that both ocean water and sand are mixtures
At the beach, you realize that both ocean water and sand are mixtures. Which is a homogeneous mixture (or solution)? Which is a heterogeneous mixture?
Salt water is a homogeneous mixture, or solution. Sand is a heterogeneous mixture.
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21. How can mixtures be separated?
Separating Mixtures
Separating Mixtures
How can mixtures be separated?
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22. Separating Mixtures
If you have a salad containing an ingredient you don't like, you can remove it with a fork.
Many mixtures are not as easy to separate.
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23. Or, you might cool the mixture until the oil turned solid.
Separating Mixtures
To separate a mixture of olive oil and vinegar, for example, you could decant, or pour off, the oil layer.
Or, you might cool the mixture until the oil turned solid.
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24. Or, you might cool the mixture until the oil turned solid.
Separating Mixtures
To separate a mixture of olive oil and vinegar, for example, you could decant, or pour off, the oil layer.
Or, you might cool the mixture until the oil turned solid.
Pouring off the oil layer takes advantage of the fact that oil floats on water.
Cooling until the oil layer turns solid takes advantage of a difference in the temperatures at which the olive oil and vinegar freeze.
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25. Differences in physical properties can be used to separate mixtures.
Separating Mixtures
Differences in physical properties can be used to separate mixtures.
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26. Separating Mixtures
Filtration
The coffee filter at right can separate ground coffee beans from brewed coffee.
The liquid brewed coffee passes through the paper filter, but the solid coffee grounds cannot pass through the filter.
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27. Filter paper used in a laboratory is similar to coffee filters.
Separating Mixtures
Filtration
Filter paper used in a laboratory is similar to coffee filters.
Filter paper is often placed in a funnel.
Then the mixture is poured into the funnel.
Solid particles that cannot pass through the filter remain in the funnel.
The rest of the particles pass through.
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28. Separating Mixtures
Filtration
The process that separates a solid from a liquid in a heterogeneous mixture is called filtration.
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29. CHEMISTRY & YOU
Brewed coffee is a mixture of ground coffee beans and water. What process is used to separate ground coffee beans from brewed coffee?
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30. CHEMISTRY & YOU
Brewed coffee is a mixture of ground coffee beans and water. What process is used to separate ground coffee beans from brewed coffee?
Filtration is used to separate ground coffee beans from brewed coffee.
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31. Separating Mixtures
Distillation
Tap water is a homogeneous mixture of water and substances that are dissolved in the water.
One way to separate water from the other components in tap water is through a process called distillation.
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32. Separating Mixtures
Distillation
During a distillation, a liquid is boiled to produce a vapor that is then condensed into a liquid.
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33. Distillation Separating Mixtures
The figure below shows an apparatus used to perform a small-scale distillation.
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34. Distillation Separating Mixtures
As water in the distillation flask is heated, water vapor forms, rises in the flask, and passes into a glass tube in the condenser.
The tube is surrounded by cold water, which cools the vapor to a temperature at which it turns back into a liquid.
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35. Distillation Separating Mixtures
As water in the distillation flask is heated, water vapor forms, rises in the flask, and passes into a glass tube in the condenser.
The tube is surrounded by cold water, which cools the vapor to a temperature at which it turns back into a liquid.
The liquid water is collected in a second flask.
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36. Distillation Separating Mixtures
The solid substances that were dissolved in the water remain in the distillation flask.
This is because their boiling points are much higher than the boiling point of water.
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37. Separating a Heterogeneous Mixture
Sample Problem 2.1
Separating a Heterogeneous Mixture
How could a mixture of aluminum nails and iron nails be separated?
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38. Analyze Identify the relevant concepts.
Sample Problem 2.1
Analyze Identify the relevant concepts. 1
In order to identify how to separate aluminum and iron nails, the properties of both aluminum and iron must be known.
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39. Solve Apply concepts to this situation.
Sample Problem 2.1
Solve Apply concepts to this situation. 2
List the properties of each substance in the mixture.
Aluminum
metal
gray color
doesn’t dissolve in water
not attracted to magnet
Iron
metal
gray color
doesn’t dissolve in water
attracted to magnet
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40. Solve Apply concepts to this situation.
Sample Problem 2.1
Solve Apply concepts to this situation. 2
Identify a property that can be used to separate different substances from each other.
The ability to be attracted by a magnet is a property that iron and aluminum do not share.
You could use a magnet to remove the iron nails from a mixture of iron and aluminum.
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41. Which physical property does filtration rely on to separate mixtures
Which physical property does filtration rely on to separate mixtures? Which does distillation rely on?
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42. Which physical property does filtration rely on to separate mixtures
Which physical property does filtration rely on to separate mixtures? Which does distillation rely on?
Filtration relies on the size of a particle, or molecule, of a substance.
Distillation relies on the boiling point of the substance.
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43. Differences in physical properties can be used to separate mixtures.
Key Concepts
Mixtures can be classified as heterogeneous mixtures or as homogeneous mixtures, based on the distribution of their components.
Differences in physical properties can be used to separate mixtures.
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44. Glossary Terms
mixture: a physical blend of two or more substances that are not chemically combined
heterogeneous mixture: a mixture that is not uniform in composition; components are not evenly distributed throughout the mixture
homogeneous mixture: a mixture that is uniform in composition; components are evenly distributed and not easily distinguished
solution: a homogeneous mixture; consists of solutes dissolved in a solvent
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45. phase: any part of a sample with uniform composition and properties
Glossary Terms
phase: any part of a sample with uniform composition and properties
filtration: a process that separates a solid from the liquid in a heterogeneous mixture
distillation: a process used to separate components of a mixture using differences in boiling points
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46. Glossary Terms
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47. Glossary Terms
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48. END OF 2.2
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