The molar mass and molecular weight of Water (H2O) is 18.0153 g/mol.
The composition of the H2O formula is as follows:
| Element | Symbol | Atomic Weight | Atoms | Total Atomic Weight | Mass Percent |
|---|---|---|---|---|---|
| Oxygen | O | 15.9994 g/mol | 1 | 15.9994 g/mol | 88.8099% |
| Hydrogen | H | 1.00797 g/mol | 2 | 2.0159 g/mol | 11.1901% |
How to find the molar mass of Water (H2O)?
The molar mass and molecular weight of Water (H2O) can be calculated in 4 steps.
Step I: Identify the different elemental atoms present in the H2O compound.
The given compound is H2O. It comprises atoms from 2 different elements i.e., Oxygen (O) and Hydrogen (H).
Step II: Find the atomic weight of each element in the H2O.
Here is the list of atomic weights for all elements, let’s check the Oxygen (O) and Hydrogen (H) atom’s atomic weight.
• The atomic weight of Oxygen (O) is 15.9994 g/mol.
• The atomic weight of Hydrogen (H) is 1.00797 g/mol.
Step III: Determine the number of atoms of each element present in the H2O compound.
As per the chemical formula, H2O, It is made up of 1 Oxygen atom and 2 Hydrogen atoms.
| Element | Number of Atoms |
|---|---|
| O (Oxygen) | 1 |
| H (Hydrogen) | 2 |
Step IV: Calculate the molar mass of the Water (H2O) compound by applying the formula:
For Water (H2O):
Substituting into the above formula, the values determined in steps II and III:
Molar mass of H2O = [(15.9994 x 1) + (1.00797 x 2)]
Molar mass of H2O = 15.9994 + 2.01594 = 18.0153 g/mol
Result: The molecular weight and molar mass of Water (H2O) is 18.0153 g/mol.
FAQs
What is the mass percent composition of Oxygen (O) in Water (H2O)? |
To find the mass percent of Oxygen in H2O, follow the steps given below:
∴ Mass of Oxygen in H2O = 15.9994 x 1 = 15.9994 g/mol. Mass Percent Composition (%) Formula = (Mass of Element in the Compound/Molar Mass of the Compound) x 100 ∴ Mass percent of Oxygen in H2O = (Mass of Oxygen in H2O/Molar mass of H2O) × 100% Result: H2O contains 88.81 % of Oxygen as per its chemical composition.
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What is the mass percent composition of Hydrogen (H) in Water (H2O)? |
To find the mass percent of Hydrogen in H2O, follow the steps given below:
∴ Mass of Hydrogen in H2O = 1.00797 x 2 = 2.0159 g/mol. Mass Percent Composition (%) Formula = (Mass of Element in the Compound/Molar Mass of the Compound) x 100 ∴ Mass percent of Hydrogen in H2O = (Mass of Hydrogen in H2O/Molar mass of H2O) × 100% Result: H2O contains 11.19 % of Hydrogen as per its chemical composition.
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What is the atomic percentage composition of elements in Water (H2O)? |
| Atomic percentage composition formula (%) = Number of atoms of a particular element in a compound/Total number of atoms in that compound
For H2O: The atomic percentage composition of elements in the compound is: Atomic percentage of Oxygen (O) in H2O: Atomic percentage of Hydrogen (H) in H2O:
|
How many grams of Oxygen are present in 1 mole of H2O? |
| There are 1 O-atoms in a H2O molecule. • Atomic weight of a O-atom = 15.9994 g/mol ∴ Total mass of Oxygen in 1 mole of H2O = 1 x 15.9994 = 16.00 g. Therefore there are 16.00 grams of Oxygen in 1 mole of H2O. |
What is the mass of 3 mol of H2O? |
| The molecular mass of H2O is 18.0153 g/mol. This means 18.0153 grams of H2O are present per mole. Therefore, we can find the mass of H2O in 3 moles as follows: ∴ Moles = Mass/Molar Mass ∴ Mass of H2O = Moles x Molar mass ∴ Mass of H2O = 3 x 18.0153 = 54.05 g Thus, the mass of 3 mol of H2O is 54.05 g. |
If you have 19.6025 grams of H2O, how many moles do you have? |
| ∴ Moles = Mass/Molar mass ∴ Moles of H2O = 19.6025/18.0153 = 1.0881 Thus, there are 1.0881 moles of H2O in its 19.6025 grams. |
What is the mass in kg of 3.00 x 1025 molecules of H2O? |
| 1 mole of a substance contains Avogadro number of particles i.e., 6.02 x 1023. Therefore, the number of moles in 3.00 x 1025 molecules of H2O are: ∴ Moles of H2O = 3.00 x 1025/6.02 x 1023 = 49.9
Now that we have its number of moles, so, we can use the molar mass of H2O (18.0153 g/mol) to find its mass as shown below. ∴ Mass of H2O = Moles x Molar mass
∴ Mass of H2O = 49.9 x 18.0153 = 898.54 g
Converting mass from grams (g) to kilograms (kg) gives us: ∴ Mass of H2O = 898.54/1000 = 0.90 kg
The mass of 3.00 x 1025 molecules of H2O is 0.90 kg.
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What is the molar mass and molecular weight of Water (H2O)? |
H2O is composed of 1 Oxygen (O), and 2 Hydrogen (H) atoms.
To find the molecular mass of H2O, one multiplies the atomic weight of each element by its number of atoms in the molecule and then sums the results. ∴ For H2O, it’s (1 x 15.9994) + (2 x 1.0080).
Therefore, the molar mass of Water (H2O) is 18.0153 g/mol.
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About the author
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/