Question

q1 chemistry: u1l3.5 locom, chemical & physical changes date:
prework part 2: types of mixtures
directions: read the passage below. as you read, annotate the important information and vocabulary words. then answer the questions.
**part 1: read & annotate:
types of mixtures
everything in the universe is made of matter. matter can be classified as either a pure substance or a mixture. pure substances are made of only one kind of particle. they can be elements, like gold or oxygen, or compounds, like water (h₂o) and carbon dioxide (co₂). because they are uniform throughout and have a fixed composition, pure substances have consistent properties.
mixtures are made of two or more substances that are physically combined. they can be separated by physical means. there are two types of mixtures: homogeneous and heterogeneous.
homogeneous mixtures have a uniform composition throughout. this means the individual components are so evenly mixed that you cannot distinguish one from another, even at the macroscopic level. at the nanoscale, the particles of different substances are interspersed so finely that they appear as one substance. an example is salt dissolved in water—the salt particles are distributed evenly among the water molecules.
heterogeneous mixtures, on the other hand, do not have a uniform composition. you can often see the different components with the naked eye or at the macroscopic level. at the macroscopic level, different types of particles remain grouped or separated in clumps or layers, depending on their properties. for example, in a mixture of sand and iron filings, the particles remain distinct and do not mix uniformly.
particle diagrams help us visualize these types of matter. pure substances show identical particles arranged uniformly. homogeneous mixtures show a random but even distribution of different types of particles. heterogeneous mixtures show clumps or separated regions of different particles, reflecting their uneven composition.
part 2: multiple choice

1. **which mixture appears the same throughout?

a. trail mix
b. oil and water
c. sand and iron filings
d. sugar dissolved in water

1. **which of the following is a pure substance?

a. saltwater
b. air
c. oxygen gas
d. salad
part 3: matching
draw a line to match each term with its correct description:

1. **homogeneous mixture

a. can be separated physically and looks the same throughout

1. **heterogeneous mixture

b. contains visibly different substances or phases

1. element

c. pure substance made of one type of atom

1. **compound

d. pure substance made of two or more types of atoms

Explanation:

1. A homogeneous mixture has a uniform composition throughout. Sugar dissolved in water is a homogeneous mixture as the sugar particles are evenly distributed among water molecules. Trail - mix, oil and water, and sand and iron filings are heterogeneous mixtures.
2. A pure substance is made of only one kind of particle. Oxygen gas is a pure substance (an element). Saltwater is a mixture, air is a mixture of gases, and salad is a heterogeneous mixture.
3. A homogeneous mixture can be separated physically and looks the same throughout.
4. A heterogeneous mixture contains visibly different substances or phases.
5. An element is a pure substance made of one type of atom.
6. A compound is a pure substance made of two or more types of atoms.

Answer:

1. D. Sugar dissolved in water
2. C. Oxygen gas
3. A. Can be separated physically and looks the same throughout
4. B. Contains visibly different substances or phases
5. C. Pure substance made of one type of atom
6. D. Pure substance made of two or more types of atoms