CHM-120 opens SNHU's general chemistry sequence for science students, and it is the foundation for CHM-121 and organic chemistry.
SNHU's catalog says students cover basic principles of chemistry, calculate the quantities of reactants and products in chemical reactions, explain thermochemistry in relation to heat, energy and enthalpy, and explain the formation of chemical bonds and molecular geometry. Students enroll concurrently in the 1-credit lab, CHM-120L.
The step up from school chemistry is the reasoning chain. A single stoichiometry problem might need a balanced equation, molar masses, a mole ratio and a limiting reagent check, and one weak link breaks the answer.
Course at a Glance
| Item | Details |
|---|---|
| University | Southern New Hampshire University (SNHU) |
| Course code | CHM-120 |
| Level | Undergraduate, first-year science |
| Credits | 3 |
| Corequisite | CHM-120L General Chemistry I Lab (1 credit) |
| Next course | CHM-121 General Chemistry II (CHM-120 is its prerequisite) |
What CHM-120 Covers
| Outcome (SNHU wording, summarized) | What it means in practice |
|---|---|
| Basic principles of chemistry | Atoms, the periodic table, formulas, naming and equations |
| Quantities of reactants and products | Moles, mole ratios, limiting reagents and percent yield |
| Thermochemistry | Heat, energy and enthalpy changes in reactions |
| Bonding and molecular geometry | Ionic and covalent bonds, Lewis structures and molecular shapes |
Key Concepts Explained
Limiting Reagent
The reactant that runs out first decides how much product forms. Convert every reactant to moles, divide by its coefficient, and the smallest result identifies the limiting reagent.
Example: 2H2 + O2 gives 2H2O. With 4.0 g of H2 (2.0 mol) and 16 g of O2 (0.50 mol): hydrogen gives 2.0 / 2 = 1.0, oxygen gives 0.50 / 1 = 0.50. Oxygen is limiting, so water formed = 0.50 x 2 = 1.0 mol, or 18 g.
Enthalpy
Enthalpy change (delta H) is the heat absorbed or released at constant pressure. A negative value means exothermic, a positive value endothermic. Calorimetry problems use q = mc(delta T) to find heat from a temperature change.
Example: Warming 100 g of water from 20 to 30 degrees C needs q = 100 g x 4.18 J/g degrees C x 10 degrees C = 4,180 J, or about 4.2 kJ.
Molecular Geometry
VSEPR theory predicts shape from electron groups around a central atom. Methane has four bonding pairs and is tetrahedral; water has two bonding pairs and two lone pairs and is bent. Shape then explains polarity and many physical properties.
Typical Assignments and How to Approach Them
| Assignment type | What it tests | How to approach it |
|---|---|---|
| Stoichiometry problem sets | Multi-step calculations | Balance first, convert to moles, then use ratios |
| Thermochemistry problems | Heat, enthalpy and sign conventions | State the system and keep track of signs |
| Bonding and shape questions | Lewis structures and VSEPR | Count valence electrons carefully before drawing |
| CHM-120L lab reports | Safe practice, data and analysis | Record units, show sample calculations, discuss error sources |
Getting the Most from CHM-120L
SNHU describes the lab as introducing laboratory techniques, modeling safe practices (personal safety, equipment storage and upkeep, chemical waste inventory) and applying problem-solving skills in a lab setting. Lab reports therefore assess both technique and reasoning.
Write your pre-lab notes before starting, record raw data exactly as measured, and show one sample calculation for each type of result. In your discussion, explain specific error sources and their likely direction, rather than general "human error".
Working with Units and Significant Figures
Many lost marks in CHM-120 come from units and significant figures rather than chemistry. Keep units attached to every number and cancel them as you go; if the final unit is wrong, the method is wrong.
For significant figures, multiplication and division keep the fewest significant figures in the data, while addition and subtraction keep the fewest decimal places. Round only at the end of a multi-step calculation to avoid accumulated errors.
Example: 2.50 g / 18.02 g/mol = 0.13873... mol. With three significant figures in 2.50, report 0.139 mol.
Where Students Get Stuck
- Skipping the balanced equation. Every ratio depends on it.
- Grams in mole ratios. Ratios work only in moles.
- Sign errors in enthalpy. Decide whether heat flows into or out of the system.
- Lone pairs forgotten. They change molecular shape even though they are not atoms.
Study Tips for CHM-120
- Practice dimensional analysis until unit canceling is automatic.
- Do a few problems daily rather than many the night before.
- Build molecular models, physical or online, to see VSEPR shapes.
- Review mistakes by naming the step that failed.
How We Help with CHM-120
Send the problem set, lab instructions and data, rubric and feedback. A chemistry tutor can prepare worked solutions, explain concepts or review your lab report. Our lab report writing guide explains report structure.
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Frequently Asked Questions
Basic chemical principles, quantities of reactants and products, thermochemistry (heat, energy and enthalpy), and chemical bonding and molecular geometry.
Yes. Students enroll concurrently in CHM-120L General Chemistry I Lab, a 1-credit course.
CHM-121 General Chemistry II, which lists CHM-120 as its prerequisite.
The lecture course is 3 credits.
Many students find multi-step stoichiometry and enthalpy sign conventions hardest. Regular practice helps most.
Yes. We review structure, calculations and discussion and explain any corrections.