CA1 Study Guide - Chemistry

⚠️ What You WILL and WILL NOT Get on the Test

You WILL receive:

The density, heat, and percent error formulas
Relevant density and specific heat values
Conversion factors (EXCEPT metric prefixes and temperature conversions)

You will NOT receive:

What variables represent or their units
Metric prefix meanings (kilo-, centi-, milli-, micro-)
Temperature conversion formulas (°C ↔ K, °F ↔ °C)

Must Know #1 Formula Variables & Their Units

Density Formula

\[D = \frac{m}{V}\]

YOU MUST MEMORIZE what each variable means and its units!

D = Density (units: g/cm³ or g/mL)

m = mass (units: g = grams)

V = volume (units: cm³ or mL)

Remember: 1 mL = 1 cm³ and water has a density of 1.0 g/mL

Heat Formula

\[q = mc\Delta T\]

YOU MUST MEMORIZE what each variable means and its units!

q = heat energy (units: J = Joules)

m = mass (units: g = grams)

c = specific heat capacity (units: J/g°C)

ΔT = change in temperature = T_final - T_initial (units: °C)

Key Concepts:

Water's specific heat: c = 4.18 J/g°C
In calorimetry: heat lost by hot object = heat gained by cold object
q_metal = -q_water (opposite signs because one gains, one loses)

Percent Error Formula

\[\text{Percent Error} = \frac{|\text{Experimental} - \text{Actual}|}{\text{Actual}} \times 100\%\]

YOU MUST MEMORIZE what each term means!

Experimental = the value you calculated/measured

Actual = the true/accepted value

| | = absolute value (make the difference positive)

Must Know #2 Metric Prefix Meanings

YOU WILL NOT GET THESE ON THE TEST - MEMORIZE THEM!

Prefix	Symbol	Meaning	Power of 10	Example
kilo-	k	1,000	\(10^3\)	1 km = 1,000 m
centi-	c	0.01 (1/100)	\(10^{-2}\)	1 m = 100 cm
milli-	m	0.001 (1/1,000)	\(10^{-3}\)	1 L = 1,000 mL
micro-	μ	0.000001 (1/1,000,000)	\(10^{-6}\)	1 m = 1,000,000 μm

Memory Trick: The prefixes go from BIG to small: kilo (1000) → base unit → centi (1/100) → milli (1/1000) → micro (1/1,000,000)

Must Know #3 Temperature Conversion Formulas

YOU WILL NOT GET THESE FORMULAS ON THE TEST - MEMORIZE THEM!

Celsius ↔ Kelvin

\[K = °C + 273.15\] \[°C = K - 273.15\]

Examples:
• 25°C = 25 + 273.15 = 298.15 K
• 373.15 K = 373.15 - 273.15 = 100°C

Fahrenheit ↔ Celsius

\[°C = \frac{5}{9}(°F - 32)\] \[°F = \frac{9}{5}(°C) + 32\]

Examples:
• 68°F = 5/9(68-32) = 5/9(36) = 20°C
• 100°C = 9/5(100) + 32 = 180 + 32 = 212°F

Important Reference Points:
• Water freezes: 0°C = 32°F = 273.15 K
• Water boils: 100°C = 212°F = 373.15 K
• Absolute zero: -273.15°C = -459°F = 0 K
• Room temperature: ~20°C = ~68°F = ~293 K

Good to Know Common Energy Conversions

Note: These will be provided, but it helps to know them!

Conversion	Factor
1 calorie (cal)	= 4.184 Joules (J)
1 Calorie (Cal) or kilocalorie (kcal)	= 1,000 calories = 4,184 J

Watch Out! Capital "C" Calorie (food calories) = 1,000 lowercase "c" calories!

Quick Reference Key Concepts Summary

Significant Figures Rules

Leading zeros are NOT significant
Trailing zeros after a decimal ARE significant
Sandwiched zeros ARE significant
Multiplication/Division: answer has same sig figs as least precise measurement
Addition/Subtraction: answer has same decimal places as least precise measurement

Physical vs. Chemical Changes

Physical: Change in form/state, NO new substance (melting, freezing, cutting, dissolving)
Chemical: New substance formed (burning, rusting, tarnishing, cooking)

Classification of Matter

Element: One type of atom (O, C, Fe, Au)
Compound: Two or more elements chemically bonded (H₂O, CO₂, NaCl)
Homogeneous Mixture: Uniform composition (salt water, air, brass)
Heterogeneous Mixture: Non-uniform, can see parts (salad, trail mix, sand in water)

Thermochemistry

Thermometer: Measures temperature (kinetic energy)
Calorimeter: Measures heat transfer between substances
Exothermic: Releases heat TO surroundings (feels hot)
Endothermic: Absorbs heat FROM surroundings (feels cold)
Higher specific heat = harder to heat up (needs more energy per degree)

⚠️ Common Assessment 1 Study Guide