CHEM 121 2026 GENERAL CHEMISTRY
COMPREHENSIVE STUDY GUIDE
◉Law of Conservation of Mass. Answer: Mass is always constant
- Reactant mass = Product mass
They are used (upheld) in chemical equations
◉Three common states of matter and their characteristics. Answer:
- Solid (s): color
- Liquid (aq): melting point, solubility
- Gas (g):
◉Difference between Elements, Compounds, Homogeneous and
Heterogeneous mixtures. Answer: - Substances: CANNOT be
separated by physical process
- Mixture: CAN be separated by physical process
- Elements: CANNOT be decomposed by chemicals
- Compounds: 2 or more elements combined
- Homogeneous: ex: salt water
- Heterogeneous: physically distinct parts (ex: sand)
, ◉Difference between Physical and Chemical changes / their
processes. Answer: Physical change: boiling, melting, change of
states of matter (solid -> liquid -> gas)
Chemical change: combustion, photosynthesis, rusting
◉physical vs chemical properties. Answer: Physical: color, melting
point, solubility, boiling point
Chemical: creativity in acid, ability to rust (react with oxygen)
◉Precision vs Accuracy. Answer: Precision: closeness to "set of
values obtained" (sample mean)
Accuracy: closeness to true value (population mean)
◉Sig Figs. Answer: 2500 = 2 sig figs
2500.0 = 5 sig figs
0.0077 = 2 sig figs
0.03400 = 4 sig figs
◉Kilogram vs Gram
Millogram vs Gram
Nanogram vs Gram. Answer: 1000g = 1kg
1000mg = 1g
COMPREHENSIVE STUDY GUIDE
◉Law of Conservation of Mass. Answer: Mass is always constant
- Reactant mass = Product mass
They are used (upheld) in chemical equations
◉Three common states of matter and their characteristics. Answer:
- Solid (s): color
- Liquid (aq): melting point, solubility
- Gas (g):
◉Difference between Elements, Compounds, Homogeneous and
Heterogeneous mixtures. Answer: - Substances: CANNOT be
separated by physical process
- Mixture: CAN be separated by physical process
- Elements: CANNOT be decomposed by chemicals
- Compounds: 2 or more elements combined
- Homogeneous: ex: salt water
- Heterogeneous: physically distinct parts (ex: sand)
, ◉Difference between Physical and Chemical changes / their
processes. Answer: Physical change: boiling, melting, change of
states of matter (solid -> liquid -> gas)
Chemical change: combustion, photosynthesis, rusting
◉physical vs chemical properties. Answer: Physical: color, melting
point, solubility, boiling point
Chemical: creativity in acid, ability to rust (react with oxygen)
◉Precision vs Accuracy. Answer: Precision: closeness to "set of
values obtained" (sample mean)
Accuracy: closeness to true value (population mean)
◉Sig Figs. Answer: 2500 = 2 sig figs
2500.0 = 5 sig figs
0.0077 = 2 sig figs
0.03400 = 4 sig figs
◉Kilogram vs Gram
Millogram vs Gram
Nanogram vs Gram. Answer: 1000g = 1kg
1000mg = 1g
