Magnesium oxide_magnesium hydroxide_magnesium carbonate ผู้ผลิตกลุ่ม-Zehui
แมกนีเซียมคาร์บอเนตมีสูตรอะไรบ้าง? MgCO₃ Explained Clearly
What is the formula of magnesium carbonate? ของมัน mgco₃ — the standard anhydrous form. Learn about variations like hydrated and basic types, plus common uses in industry and sports.
I’ve fielded the question what is the formula of magnesium carbonate from clients, students, and formulators more times than I can remember.
Most people expect a single clean answer.
The core, anhydrous compound is indeed mgco₃.
That’s the formula you’ll see in textbooks, PubChem, and basic specs.
But in real-world supply and applications, things get a little more nuanced.
Commercial “แมกนีเซียมคาร์บอเนต” is often a hydrated or basic form.
Let’s break it down plainly so you know exactly what you’re dealing with.
The Standard Chemical Formula: mgco₃
mgco₃ is the simplest and most fundamental formula.
- มก.— magnesium cation (มก.²⁺)
- CO₃— carbonate anion (CO₃²⁻)
One magnesium balances one carbonate.
Molecular weight: ≈84.31 g/mol
This is the anhydrous form, known mineralogically as แมกนีไซต์.
It’s a white, crystalline solid with a calcite-like structure.
Common Commercial Variations and Their Formulas
When people buy “แมกนีเซียมคาร์บอเนต” for pharma, อาหาร, ยาง, or gym chalk, they usually get one of these:
- Light magnesium carbonate— often approximated as basic hydrated forms like (mgco₃)₄·Mg(โอ้)₂·4H₂O or similar. Very fluffy, low density.
- Heavy magnesium carbonate— denser, frequently (mgco₃)₃·Mg(โอ้)₂·3H₂O or tetrahydrate versions. More compact.
These are basic magnesium carbonates (also called magnesium hydroxide carbonate).
Typical formulas you’ll see in specs:
- Light: roughly (mgco₃)₃·Mg(โอ้)₂·3H₂O
- Heavy: roughly (mgco₃)₃·Mg(โอ้)₂·4H₂O or Mg₅(CO₃)₄(โอ้)₂·4H₂O (hydromagnesite-like)
They contain both carbonate and hydroxide groups, plus water.
That’s why the MgO content is often listed as 40–45% instead of the ~47% for pure MgCO₃.
Why the Formula Matters in Applications
The exact composition affects performance.
- ชอล์กยิม / climbing chalk— almost always light, fluffy basic magnesium carbonate. High surface area for sweat absorption.
- Rubber and plastics filler— heavier, denser grades for better loading and reinforcement.
- Pharma antacids— basic hydrated forms for controlled acid neutralization.
- Precursor to MgO— calcined (heated) to drive off CO₂ and H₂O, regardless of starting hydration.
A rubber compounder I know once ordered “แมกนีเซียมคาร์บอเนต” without specifying light or heavy.
Got the light fluffy version instead of the dense one he needed.
Mixing time doubled, dispersion was poor, and batch scrapped.
Specifying “heavy magnesium carbonate” fixed it next run.
Small detail, big cost.
Quick Reference: Magnesium Carbonate Formulas at a Glance
| Type/Form | Common Formula Approximation | Density / Character | Typical Use |
| Anhydrous (แมกนีไซต์) | mgco₃ | High density, crystalline | Rare commercially, reference only |
| Light magnesium carbonate | (mgco₃)₃·Mg(โอ้)₂·3H₂O or similar | Very low density, fluffy | ชอล์กยิม, absorbent, ยา |
| Heavy magnesium carbonate | (mgco₃)₃·Mg(โอ้)₂·4H₂O or Mg₅(CO₃)₄(โอ้)₂·4H₂O | Higher density | Rubber filler, สารหน่วงไฟ |
| Hydrated forms | MgCO₃·nH₂O (n=2–5, เช่น, barringtonite, nesquehonite) | Variable | Specialty, less common |
คำถามที่พบบ่อย
What is the simplest formula of magnesium carbonate? mgco₃ — that’s the anhydrous, theoretical form (แมกนีไซต์).
Is gym chalk really MgCO₃? ใช่, but usually a light basic hydrated version — not pure anhydrous MgCO₃.
Why do specs list magnesium carbonate as having 40–45% MgO? Commercial products are basic/hydrated forms. Pure MgCO₃ would be ~47% MgO.
What’s the difference in formula between light and heavy magnesium carbonate? Both are basic hydrated carbonates, but light versions have slightly less water or different crystal habits, leading to lower bulk density.
Can magnesium carbonate be anhydrous in products? Rarely. Most supplied material includes hydration or basic character for stability and handling.
ดังนั้นเมื่อมีคนถาม what is the formula of magnesium carbonate, start with mgco₃ — then clarify whether they mean the pure anhydrous or the common commercial basic/hydrated types.
It’s a small distinction that saves a lot of troubleshooting downstream.
