The Chemistry Requirement for Respiratory Therapy School: One Semester or Two- whether respiratory therapy programs require chemistry, the difference between a one-semester and a two-semester requirement, and how to satisfy it online.
Chemistry is one of the more variable prerequisites for respiratory therapy school. Some programs require it and some do not, and among those that do, the amount varies — many associate degree programs accept a single semester of college chemistry, while upper-division bachelor’s programs more often expect a full general chemistry sequence. That variability is exactly why it pays to understand the requirement before you plan your coursework.
This guide explains when respiratory therapy programs require chemistry, how to read a one-semester versus a two-semester requirement, what the course covers and why it is relevant to respiratory care, and how you can complete chemistry online. Chemistry usually appears alongside anatomy and physiology and microbiology on the science prerequisite list, and you can verify any program’s exact requirements through the Commission on Accreditation for Respiratory Care (CoARC).
Short answer: Many — though not all — respiratory therapy programs require chemistry, usually with a lab and a grade of C or higher. The amount differs by program: a single semester of college chemistry is common for associate programs, while a two-semester general chemistry sequence is more typical for bachelor’s programs. At PrereqCourses.com these map to CHEM 151 (General Chemistry I) and CHEM 152 (General Chemistry II), so you can take just the first course or the full sequence depending on what your program asks for.
Sometimes — and this is the key difference from anatomy and physiology, which is nearly universal. Chemistry is a common respiratory therapy prerequisite, but it is not required everywhere. Whether you need it, and how much, depends on the specific program and the degree level.
A few patterns help make sense of the landscape:
Because chemistry is the most variable of the core science prerequisites, confirming your specific program’s requirement — including whether it is needed at all, and whether one semester or two is expected — is the single most important step before you enroll.
When a program does require chemistry, the wording usually signals how much you need. Learning to read that wording saves you from taking too little (and falling short) or too much (and wasting time and money). Here is how the common phrasings typically translate:
| If the requirement says… | It usually means… |
|---|---|
| “One semester of college chemistry with lab” | A single introductory or general chemistry course with a lab — satisfied by CHEM 151 alone. |
| “General chemistry” or “chemistry (complete sequence)” | The full two-semester general chemistry sequence — satisfied by CHEM 151 and CHEM 152. |
| “Chemistry I and II” | Explicitly two semesters — both CHEM 151 and CHEM 152. |
| “One year of high school chemistry with lab” (accepted) | High school chemistry may substitute; a college course is optional but can strengthen a competitive application. |
| No chemistry listed | Chemistry may not be required — but verify directly, since requirements change. |
If you are still deciding between programs, or you may eventually pursue a bachelor’s degree, completing the full sequence is the safer bet — two semesters will satisfy a one-semester requirement, but one semester will not satisfy a two-semester requirement. If you are committed to a single associate program that asks for only one semester, CHEM 151 on its own is usually enough.
Even where it is not strictly required, chemistry underpins a surprising amount of respiratory care. The field is built on the behavior of gases, the chemistry of the blood, and the way the body maintains a stable internal environment — all of which are chemistry at their core.
A few examples of where chemistry shows up in the work:
| Respiratory care concept | Chemistry it draws on |
|---|---|
| Oxygen and medical gas delivery | The gas laws — how pressure, volume, and temperature relate — which govern how gases are stored, delivered, and behave in the lungs. |
| Acid–base balance and blood gases | pH, buffers, and chemical equilibrium, which explain how the body keeps blood chemistry within a narrow, survivable range. |
| Gas exchange in the lungs | Partial pressures, diffusion, and solubility, which describe how oxygen and carbon dioxide move between air and blood. |
| Medication concentrations and dosing | Solutions, concentration, and basic chemical math used when preparing and administering inhaled medications. |
| Understanding pharmacology later | Molecular structure and reactions, which make the pharmacology coursework in a respiratory therapy program easier to grasp. |
The gas laws and acid–base balance in particular are not optional knowledge for a respiratory therapist — they are daily working concepts. That is why even programs that do not formally require chemistry benefit students who arrive with it. For a broader sense of the profession, the American Association for Respiratory Care (AARC) is the field’s main professional organization.
A standard general chemistry sequence introduces the core principles of matter and reactions, then builds toward the topics most relevant to the health sciences. Organization varies by institution, but the typical breakdown looks like this:
If your program requires only one semester, the gas-law content in the first course is the most directly applicable to respiratory care. If you complete both, the acid–base and equilibrium material in the second course maps closely onto blood gas interpretation later in your training.
Most chemistry requirements specify a lab. A traditional chemistry lab teaches measurement, safe handling of substances, and hands-on experiments that reinforce the lecture concepts. Because lab policies differ, confirm whether your respiratory therapy program accepts an online or virtual chemistry lab before you enroll.
Yes — chemistry is widely available online, and for working adults and career changers it is often the most practical route. The lecture content translates well to a self-paced online format. As with microbiology, the variable that needs the most attention is the lab.
Before enrolling in any online chemistry course, confirm that it meets these conditions:
The lab, in plain terms: programs handle the chemistry lab differently — some accept an online or virtual lab, others prefer or require a hands-on lab. Email your program’s admissions office, describe the course you are considering, and get their answer in writing before you enroll.
At PrereqCourses.com, the respiratory therapy chemistry requirement is satisfied by CHEM 151 (General Chemistry I) and CHEM 152 (General Chemistry II) — self-paced, online courses delivered through our regionally accredited university partner, with an official transcript you can submit to your program. Because the requirement varies, you can take just the first course for a one-semester requirement or both for a full sequence.
| Course | Satisfies | Focus for RT applicants |
|---|---|---|
| CHEM 151 | One-semester chemistry requirement, or first half of a sequence | Atomic structure, bonding, reactions, and the gas laws central to medical gas delivery. |
| CHEM 152 | Second half of a two-semester general chemistry sequence | Solutions, equilibrium, and acids/bases/pH — the foundation for blood gas and acid–base concepts. |
What makes the format work for respiratory therapy applicants:
Important — confirm requirement and lab first: because chemistry requirements (and lab policies) vary so much between respiratory therapy programs, send the CHEM 151 and CHEM 152 course descriptions to your target program’s admissions office and ask them to confirm whether chemistry is required, how many semesters, and how they handle the lab — before you enroll.
Is chemistry required for respiratory therapy school?
It depends on the program. Many require it, but some do not. Among those that do, associate programs often accept one semester while bachelor’s programs may expect a full sequence. Always confirm with your specific program.
Do I need one semester or two semesters of chemistry?
Read the requirement wording: “one semester of college chemistry” means one course (CHEM 151), while “general chemistry,” “complete sequence,” or “Chemistry I and II” means two (CHEM 151 and CHEM 152). When in doubt, the full sequence satisfies both.
Does chemistry need to include a lab?
Usually yes — most chemistry requirements specify a lab. Policies on online and virtual labs vary, so confirm what your program accepts before enrolling.
Will high school chemistry count?
Some programs accept one year (or two semesters) of high school chemistry with a lab, sometimes paired with an additional biology requirement. Others require a college course. Check your program’s rule.
What grade do I need in chemistry?
A grade of C or higher is the typical minimum, and many programs explicitly do not accept a C-minus. Your science GPA may also affect how competitive your application is.
How recent does my chemistry credit need to be?
Many programs prefer or require natural-science prerequisites completed within the last 5 to 10 years. Older credit may need to be retaken.
Chemistry is the most variable of the core respiratory therapy science prerequisites: required by many programs but not all, and ranging from a single semester to a full general chemistry sequence. The work itself — gas laws, acid–base balance, blood gases — leans heavily on chemistry, so it is valuable even where it is optional. Completing chemistry online, through regionally accredited and self-paced coursework, lets you satisfy the requirement on a schedule that works for you, provided you first confirm whether it is required, how much, and how the lab is handled. After you graduate from a CoARC-accredited program, the National Board for Respiratory Care (NBRC) administers the exams that lead to credentialing and licensure.
Ready to get started? Explore CHEM 151 (General Chemistry I) and CHEM 152 (General Chemistry II) at PrereqCourses.com, and confirm the requirement — including the lab — with your respiratory therapy program before enrolling.
Chemistry is one of several prerequisites respiratory therapy programs may require. Explore the rest of the science and general-education sequence:
Whether chemistry is required, the number of semesters, grade minimums, recency windows, and lab policies vary by institution and change over time. This article is for general guidance only. Always confirm requirements directly with the respiratory therapy program you intend to apply to.
