Question

homework - due in class 9/18 (thursday)
classifying matter - classify the following examples as an element, compound, or mixture:

1. ammonia nh₃ - compound
2. hydrogen - element
3. salt water nacl(aq) - mixture
4. steel containing 3% carbon - compound
5. sodium hydroxide naoh - compound
6. mixture 1 (homogeneous/heterogeneous)
7. mixture 2 (homogeneous/heterogeneous)
8. describe the difference between a heterogeneous and homogeneous mixture:

a hetero mixture is a substance not mixed subsequently and a homo mixture is a substance mixed evenly.
phases - 9. molecules of kcl in the solid phase
a. move slowly in straight lines
b. move rapidly in straight lines
c. are arranged in a regular geometric pattern
d. are arranged in a random pattern

1. draw a particle diagram of h₂o in the gaseous phase. use shading to differentiate hydrogen from oxygen.

information about two mixtures at 20.°c

mixture 1	mixture 2

|student observations|colorless liquid
no visible solid on bottom of beaker|colorless liquid
black solid on bottom of beaker|

other data

mass of nacl(s) dissolved = 2.9 g

mass of fe(s) = 15.9 g

density of fe(s) = 7.87 g/cm³|

Explanation:

Step1: Define homogeneous and heterogeneous mixtures

A homogeneous mixture has a uniform composition throughout, while a heterogeneous mixture has a non - uniform composition with visible different parts.

Step2: Analyze Mixture 1

NaCl in H₂O forms a solution where the salt is uniformly dissolved in water. There are no visible separate parts. So, Mixture 1 is homogeneous.

Step3: Analyze Mixture 2

Fe filings in H₂O have a black solid (Fe filings) at the bottom of the beaker. The composition is not uniform as there are distinct solid and liquid parts. So, Mixture 2 is heterogeneous.

Step4: Answer question 9

In the solid phase, molecules of KCl are arranged in a regular geometric pattern (lattice structure). So the answer is c.

Step5: Regarding question 10

In the gaseous phase of H₂O, water molecules are far apart and move freely. For a particle diagram, you can draw small circles to represent hydrogen atoms (lightly shaded) and larger circles to represent oxygen atoms (darker shaded), with the molecules separated from each other.

Answer:

1. Homogeneous
2. Heterogeneous
3. c. Are arranged in a regular geometric pattern
4. Draw separate H₂O molecules with hydrogen atoms (lightly shaded) and oxygen atoms (darker shaded) far apart to represent the gaseous phase.