How Many Hydrogen Atoms Are in 150.0g of Glucose?
You've got a chemistry problem sitting in front of you, and you're trying to figure out how many hydrogen atoms are packed into 150 grams of glucose. Maybe it's homework. In practice, maybe you're studying for a test. Even so, maybe you're just curious. Either way, you're in the right place Simple, but easy to overlook..
The short answer is approximately 6.02 × 10²⁴ hydrogen atoms. But that number doesn't mean much without understanding how we get there — and honestly, the process is what matters. Let me walk you through it step by step, the way I'd explain it to a friend who was stuck on the same problem That's the part that actually makes a difference..
Most guides skip this. Don't.
What Is Glucose (and Why Does This Calculation Matter)?
Glucose is a simple sugar — the primary source of energy for your cells. Its chemical formula is C₆H₁₂O₆, which tells you everything you need to know: each glucose molecule contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.
Here's the thing about chemistry problems like this: they're not about memorizing numbers. On top of that, once you see how moles, molar mass, and Avogadro's number work together, you can solve almost any "how many atoms in X grams of substance" problem. They're about understanding relationships. Glucose is just the vehicle for learning the method Worth keeping that in mind. But it adds up..
The key concepts you'll need are:
- Molar mass — the mass of one mole of a substance
- Moles — a unit that lets us count atoms by weighing them
- Avogadro's number — 6.022 × 10²³, which is how many particles are in one mole
Why This Shows Up So Often in Chemistry Class
This exact type of problem — "how many atoms of element X are in Y grams of compound Z" — is a staple of general chemistry courses. That said, it tests whether you understand how to move between the macroscopic world (grams, beakers, balances) and the microscopic world (atoms, molecules, particles). It's also genuinely useful if you ever go on to work in biochemistry, pharmacology, or nutrition science.
How to Calculate the Number of Hydrogen Atoms in 150.0g of Glucose
Here's the step-by-step process. I'll walk you through each stage so it's impossible to get lost.
Step 1: Find the Molar Mass of Glucose
You need to know how much one mole of glucose weighs. This comes from the periodic table and the formula C₆H₁₂O₆ Simple as that..
- Carbon (C): 12.01 g/mol × 6 = 72.06 g/mol
- Hydrogen (H): 1.008 g/mol × 12 = 12.096 g/mol
- Oxygen (O): 16.00 g/mol × 6 = 96.00 g/mol
Total molar mass = 72.06 + 12.096 + 96.00 = 180.16 g/mol
(You might see 180.15 g/mol depending on which atomic masses your textbook uses — the small difference won't change your final answer much.)
Step 2: Convert Grams to Moles
Now you take your 150.0 grams and divide by the molar mass:
Moles of glucose = 150.0 g ÷ 180.16 g/mol = 0.8326 mol
This tells you how many moles of glucose you have. It's not the number of molecules yet — it's just an intermediate step Worth keeping that in mind..
Step 3: Find the Number of Glucose Molecules
This is where Avogadro's number comes in. One mole of anything contains 6.022 × 10²³ particles.
Molecules of glucose = 0.8326 mol × 6.022 × 10²³ molecules/mol = 5.015 × 10²³ molecules
Step 4: Calculate Hydrogen Atoms
Each glucose molecule has 12 hydrogen atoms. Multiply:
Hydrogen atoms = 5.015 × 10²³ molecules × 12 atoms/molecule = 6.018 × 10²⁴ atoms
Rounding to the proper significant figures (your 150.0g has four, so carry that through), you get approximately 6.02 × 10²⁴ hydrogen atoms.
Common Mistakes People Make
Let me be honest — this is where most students trip up. Here's what to watch out for:
Forgetting to multiply by the subscript. Some people stop at the number of glucose molecules and report that as their answer. But the question asks for hydrogen atoms, not glucose molecules. You have to multiply by 12 Small thing, real impact..
Using the wrong molar mass. If you accidentally use the atomic mass of carbon (12.01) as the molar mass of glucose instead of calculating 180.16 g/mol, your answer will be way off. Always calculate it from the formula.
Rounding too early. If you round 180.156 to 180 at the beginning, then round again at the end, your significant figures will suffer. Keep extra digits in intermediate steps and only round at the final answer.
Confusing moles and molecules. A mole is a number (like a dozen, but incomprehensibly larger). It's not a mass or a volume — it's just a count. Keeping this straight in your head solves a lot of confusion And that's really what it comes down to..
Practical Tips for Solving Similar Problems
Here's what actually works when you're tackling these calculations:
-
Write down everything you know. Formula, molar masses, what you're solving for. Seeing it on paper beats trying to hold it all in your head.
-
Set up your dimensional analysis. This is the "factor-label method" your teacher probably talks about. It looks like this:
150.Practically speaking, 0 g glucose × (1 mol glucose / 180. 16 g) × (6. The units cancel out and leave you with hydrogen atoms. It's foolproof once you get the hang of it. -
Check your answer with a rough estimate. If you got something like 10²⁰ atoms, that's probably wrong — 150g is a lot of glucose, so the number should be huge. A quick sanity check catches big errors That's the whole idea..
-
Know your significant figures. If your input is 150.0g (four sig figs), your answer should reflect that precision. Most textbooks expect three sig figs for this problem, giving you 6.02 × 10²⁴.
FAQ
How many atoms are in 150g of glucose total?
If you want all atoms (carbon + hydrogen + oxygen), you'd calculate each separately: 6 carbons × 5.015 × 10²³ = 6.In real terms, 015 × 10²³ = 3. 02 × 10²⁴ hydrogen atoms, and 6 oxygens × 5.01 × 10²⁴ carbon atoms, 12 hydrogens × 5.01 × 10²⁴ oxygen atoms. 015 × 10²³ = 3.Total ≈ 1.20 × 10²⁵ atoms.
What is Avogadro's number and why does it matter?
Avogadro's number (6.022 × 10²³) is the number of particles in one mole of any substance. It bridges the gap between the tiny world of atoms and the measurable world of grams. Without it, we'd have no way to count atoms by weighing them.
Does the type of glucose matter?
For this calculation, no. Whether it's alpha-glucose or beta-glucose, the molecular formula is the same (C₆H₁₂O₆), so the number of hydrogen atoms per gram is identical.
Can I use this method for other compounds?
Absolutely. This exact process works for any compound: find the molar mass, convert grams to moles, multiply by Avogadro's number, then multiply by the subscript of the element you care about. It's the general method for "how many atoms in X grams" problems.
Why do chemists use moles instead of just counting atoms?
Because atoms are too small to count. A single grain of sugar contains quadrillions of molecules. In practice, the mole lets us work with manageable numbers while still representing the same relative amounts. It's like using "dozen" instead of counting eggs one by one — but on a cosmic scale.
The Bottom Line
So there you have it: 6.Think about it: 0 grams of glucose. 02 × 10²⁴ hydrogen atoms in 150.That's roughly six sextillion hydrogen atoms, if you want to try to wrap your mind around that number.
The process might seem like a lot of steps, but it all boils down to this: convert grams to moles, use Avogadro's number to get molecules, then multiply by however many hydrogen atoms each molecule has. Once you've done it a couple times, it becomes second nature Simple, but easy to overlook..
If you're working through chemistry problems, the best advice I can give is this — don't just look for the answer. Understand the chain of logic that gets you there. That's what actually sticks And that's really what it comes down to..
