Calculate the moles present in 2.00 grams of H2O. (Molar mass of H2O 18.015 g/mol) 1.11 mol H2O 0.111 mol H2O 2.22 mol H2O 1.22 mol H2O
The Correct Answer and Explanation is:
To calculate the number of moles in 2.00 grams of water (H2O), you need to use the formula for moles: moles=mass of substance (g)molar mass of substance (g/mol)\text{moles} = \frac{\text{mass of substance (g)}}{\text{molar mass of substance (g/mol)}}moles=molar mass of substance (g/mol)mass of substance (g)
Step 1: Identify the given values
- Mass of water = 2.00 grams
- Molar mass of H2O = 18.015 g/mol
Step 2: Substitute the values into the equation
moles=2.00 g18.015 g/mol\text{moles} = \frac{2.00 \, \text{g}}{18.015 \, \text{g/mol}}moles=18.015g/mol2.00g
Now, let’s do the division: moles=0.111 mol\text{moles} = 0.111 \, \text{mol}moles=0.111mol
Conclusion
The number of moles in 2.00 grams of water is 0.111 moles.
Explanation
To understand this calculation, let’s break it down. The molar mass of a compound tells you how much one mole of that substance weighs. For water (H2O), its molar mass is 18.015 g/mol. This means that one mole of water weighs 18.015 grams.
When you have 2.00 grams of water, you want to determine how many moles of water that corresponds to. You divide the mass of the sample by the molar mass of water to convert from grams to moles. The result is 0.111 moles of H2O.
This method can be applied to any substance as long as you know its molar mass. You can use the same formula with different masses and molar masses to calculate moles for other compounds. The concept of moles is central to chemistry because it allows chemists to work with amounts of substances in a manageable way and helps them make conversions between different units, such as grams and molecules or atoms.
