Chemistry Unit 1 Chapter 1 Study Notes: Alchemy, Matter, and Density

Unit 1: Alchemy - Chapter 1 Overview

Course Schedule and Deadlines

Date: 8/12 - 8/13

In-Class Activities: Review Policy Sheet and Lesson 1.
Homework Due: Return signed policy sheet; complete Page 6, Problems # $3$ , $5$ , and $11$ .

Date: 8/14 - 8/17

In-Class Activities: Lessons 2 and 3.
Homework Due: Page 9, Problems # $1$ and $9$ ; Page 13, Problems # $1$ , $7$ , and $10$ .

Date: 8/18 - 8/19

In-Class Activities: Lessons 4 and 5.
Homework Due: Page 17, Problems # $6$ , $7$ , and $10$ ; Page 21, Problems # $4-7$ , and $10$ .

Date: 8/20 - 8/21

In-Class Activities: Chapter 1 Quiz.

Daily Warm-Up Questions and Discussion

Date: 12-13

Question: What is one thing you do outside of school that you enjoy?
My Answer: Musical theatre.

Date: 8/14-17

Question: Draw and label a beaker, test tube, Erlenmeyer flask, and graduated cylinder.
Class Answer:
- Beaker: A wide cylindrical container with a flat bottom and a lip for pouring.
- Erlenmeyer flask: A conical flask with a flat bottom and a narrow neck.
- Test tube: A thin glass tube closed at one end, used to hold small amounts of material.
- Graduated cylinder: A tall, narrow container with marking lines used to measure the volume of a liquid.

Date: 8/18-19

Question: You find a gold ring on the ground at the park. You want to determine if it is real gold. How would you find its density to determine this?
My Answer: Take a scale to find the weight, then subtract. Next, put it in water and see how much the level rises when dropped into the graduated cylinder.
Class Answer (Water Displacement):
- Fill a graduated cylinder to a known volume and record it.
- Add the ring and record the new volume ( $V_{final}$ ).
- Subtract the initial volume from the final volume to find the displacement.

Lesson 1: Lab Equipment and Safety

Pre-Laboratory Procedures

Carefully read all directions before starting.
Look at your surroundings to ensure safety.
If using hazardous materials, locate all emergency equipment.

Post-Laboratory Procedures

Organize all tools and return them to their proper places.
Clean all supplies used.
Leave the workstation exactly as it was found.

Eye Safety Protocols

The eye wash station is a critical piece of safety equipment.
If a liquid splashes into the eye and causes a burning sensation, the eye must be flushed thoroughly with water to remove the substance.

Essential Laboratory Equipment

Safety Items: Fire blanket, eye wash station, first aid kit, fire extinguisher, safety shower, goggles, aprons/lab coats, and fume hood.
Glassware and Containers: Test tubes, watch glass, Erlenmeyer flask, burette, beaker ( $500\,mL$ ), and funnel.
Handling and Cleanup: Test tube rack, test tube brush, test tube holder, spatula, utility clamp, tongs, and wash bottle.
Measurement and Heating: Balance or scale, weighing paper, hot plate, boiling stones, thermometer, graduated cylinder, and Bunsen burner.
Specialized Tools: Magnetic stirrer, pipette and bulb, stirring rod, clay triangle, crucible, litmus paper or pH paper, tubing, striker, wire gauze, and ring stand.

Lesson 2: Introduction to Chemistry and Alchemy

Historical Context

Alchemists developed many of the tools and techniques that are still employed in modern chemistry laboratories.

Properties of Gold vs. Copper

Hardness: Gold is a soft metal, whereas copper is harder. In a scratch test, the softer metal will bend when pressed against the harder metal.
Color: The visual appearance differs between the two metals.
Melting Temperature: Each metal has a specific temperature (heat) at which it transitions from solid to liquid.

Experiment: A Penny for Your Thoughts

Purpose: To observe a chemical transformation firsthand.
Materials: Hot plate, beaker, tongs, rubber mat, and 3 M sodium hydroxide ( $NaOH$ ).
Chemical Observations:
- Penny: Shiny, reddish-brown, cylinder-shaped solid.
- Zinc ( $Zn$ ): Gray-silver powder.
- $3\,M$ Sodium Hydroxide ( $NaOH$ ): Clear, colorless liquid.
- Water ( $H_2O$ ): Clear, see-through, colorless liquid.
Safety Considerations: Goggles must be worn, closed-toed shoes are required, and long hair must be pulled back.
Procedure and Results:
- Stage 1: Zinc and sodium hydroxide are heated. The $NaOH$ fills the beaker halfway. A slightly putrid odor is present, and bubbles form.
- Stage 2: A penny is placed in the heated mixture using tongs. After a few minutes, the penny begins to change color.
- Stage 3: The penny is rinsed in cold water. It appears silver.
- Stage 4: The silver-looking penny is placed back on the hot plate. It turns a gold color.
Chemical Analysis:
- The change is a chemical reaction involving zinc.
- The "silver" color is caused by a zinc coating from the heated solution.
- The "gold" color is produced by the application of heat to the zinc-coated copper.
- The penny is likely not real gold. Testing can be done using acid reactivity, scratch tests, or density measurements.

Lesson 3: Defining Matter

Categorizing Matter

Matter: Bacteria, batteries, DNA, clouds, helium, car exhaust, atoms, dust.
Not Matter: Heat, electricity, sound, wisdom, fear.
Uncertain: Fire and wind (wind is often categorized as the movement of matter).

Defining Characteristics of Matter

Has mass/weight.
Has volume (takes up space).
Composed of atoms.
Exists in states: solid ( $s$ ), liquid ( $l$ ), gas ( $g$ ), or plasma.

Comparative Measurements

Mass: Measures the amount of matter in an object.
Volume: Measures the amount of space an object occupies.
Measuring Volume of Irregular Objects (e.g., a key): Use a graduated cylinder. Record the initial water volume, add the key, record the new volume, and subtract to find the difference.
Standard Units: Using quantities like "8 apples" is a poor unit of measure because apples vary in size.

Lesson 4 & 5: Mass, Volume, and Density

Density Theory

Density is defined as mass divided by volume: $Density = \frac{mass}{volume}$ .
High density indicates that particles are packed together tightly.
Density is a ratio and does not change based on the size of the sample (e.g., an iron nail and an iron frying pan have the same density).

Data and Calculations

Object	Mass ( $g$ )	Volume ( $mL$ )	Density ( $g/mL$ )
$5\,cm$ Gold-colored rod	$55.4\,g$	$6.6\,mL$	$8.4\,g/mL$
$5\,cm$ Silver-colored rod	$17.8\,g$	$6.6\,mL$	$2.7\,g/mL$
$10\,cm$ Silver-colored rod	$35.6\,g$	$13.2\,mL$	$2.7\,g/mL$
$10\,cm$ Crayon	$3.2\,g$	$13.3\,mL$	$0.24\,g/mL$ ( $Notes\ interpret\ as\ 6.2$ )

Experimental Observations

Predictions: The $10\,cm$ silver rod was predicted to have the greatest mass and volume; the blue crayon was predicted to have the least mass and volume.
Volume Comparison: The $5\,cm$ gold rod and $5\,cm$ silver rod have identical volumes ( $6.6\,mL$ ), but the gold rod is significantly more massive ( $55.4\,g$ vs $17.8\,g$ ).
Matter Content: The $10\,cm$ silver rod contains more matter than the $5\,cm$ gold rod because it takes up more space.
Same Size, Different Mass: This occurs due to differing densities (how tightly the particles are packed).
Same Mass, Different Volume: Possible if the substances have different densities.

Metal Identification based on Density

Aluminum ( $Al$ ): $2.7\,g/mL$ (Matches silver-colored rods).
Zinc ( $Zn$ ): $7.1\,g/mL$ .
Brass: $8.4\,g/mL$ (Matches gold-colored rods).
Copper ( $Cu$ ): $9.0\,g/mL$ .
Gold ( $Au$ ): $19.3\,g/mL$ .

Analysis of the "Gold" Penny

Penny Mass: $3.1\,g$
Penny Volume: $0.36\,mL$
Calculated Density: $\frac{3.1\,g}{0.36\,mL} = 8.6\,g/mL$
Conclusion: The penny produced in class is not real gold, as its density ( $8.6\,g/mL$ ) is much lower than that of real gold ( $19.3\,g/mL$ ).

Practice Problems

Density of Unknown Metal: A piece of metal with a volume of $30.0\,mL$ and a mass of $81.0\,g$ has a density of $\frac{81.0\,g}{30.0\,mL} = 2.7\,g/mL$ , identifying it as Aluminum.
Mass of a $1\,cm^3$ Cube: If a metal has a density of $8.4\,g/mL$ , a $1\,cm^3$ cube would have a mass of $8.4\,g$ because $1\,mL = 1\,cm^3$ .