How many moles of K2SO4 are in 15.0 grams of K2SO4
The Correct Answer and Explanation is:
To calculate the number of moles of K₂SO₄ in 15.0 grams of the compound, we need to follow these steps:
Step 1: Find the molar mass of K₂SO₄
The molar mass of a compound is the sum of the atomic masses of all the elements in that compound, based on the periodic table. Potassium (K), sulfur (S), and oxygen (O) are the elements in potassium sulfate (K₂SO₄).
- Potassium (K): Atomic mass = 39.1 g/mol
- Sulfur (S): Atomic mass = 32.1 g/mol
- Oxygen (O): Atomic mass = 16.0 g/mol
To find the molar mass of K₂SO₄, multiply the atomic masses by the number of atoms of each element in the formula:
[
\text{Molar mass of K₂SO₄} = (2 \times 39.1 \, \text{g/mol}) + (1 \times 32.1 \, \text{g/mol}) + (4 \times 16.0 \, \text{g/mol})
]
[
\text{Molar mass of K₂SO₄} = 78.2 \, \text{g/mol} + 32.1 \, \text{g/mol} + 64.0 \, \text{g/mol} = 174.3 \, \text{g/mol}
]
Step 2: Use the molar mass to calculate the number of moles
Now that we know the molar mass of K₂SO₄ is 174.3 g/mol, we can use the formula:
[
\text{Moles of K₂SO₄} = \frac{\text{Mass of K₂SO₄}}{\text{Molar mass of K₂SO₄}}
]
Substitute the given mass (15.0 grams) and the molar mass (174.3 g/mol):
[
\text{Moles of K₂SO₄} = \frac{15.0 \, \text{g}}{174.3 \, \text{g/mol}} = 0.086 \, \text{moles}
]
Final Answer:
The number of moles of K₂SO₄ in 15.0 grams is 0.086 moles.
Explanation:
The process of converting grams to moles involves using the molar mass of the substance. The molar mass tells us how many grams one mole of a substance weighs. By dividing the mass of the substance by the molar mass, we determine how many moles are present in the sample. This concept is critical in stoichiometry for converting between mass and the amount of substance in moles, allowing us to perform calculations in chemical reactions.