What is the approximate mass of Fe2(SO4)3 in 20.0 mL of a 0.200 M Fe2(SO4)3 solution? The molar mass of Fe2(SO4)3 is 400 g/mol. 40.0 g 1.60 g More than one of these choices is correct 1,600 g 1.60 kg
The Correct Answer and Explanation is:
To find the mass of Fe₂(SO₄)₃ in a 20.0 mL solution with a concentration of 0.200 M, we can use the formula:
mass = molarity × volume × molar mass
Step-by-step calculation:
- Convert volume from milliliters to liters:
20.0 mL=0.0200 L20.0\ \text{mL} = 0.0200\ \text{L}20.0 mL=0.0200 L
- Use the molarity to find moles of Fe₂(SO₄)₃:
moles=0.200 mol/L×0.0200 L=0.00400 mol\text{moles} = 0.200\ \text{mol/L} \times 0.0200\ \text{L} = 0.00400\ \text{mol}moles=0.200 mol/L×0.0200 L=0.00400 mol
- Multiply by molar mass to find mass in grams:
mass=0.00400 mol×400 g/mol=1.60 g\text{mass} = 0.00400\ \text{mol} \times 400\ \text{g/mol} = 1.60\ \text{g}mass=0.00400 mol×400 g/mol=1.60 g
Final Answer:
1.60 g
Explanation:
This problem involves converting the volume of a solution into moles using molarity, then using the molar mass to calculate the mass of solute in the given volume. Molarity is a way to express concentration and is defined as moles of solute per liter of solution. Since the volume given is in milliliters, it must be converted into liters for consistent units.
Multiplying the molarity by the volume gives the number of moles of Fe₂(SO₄)₃ present in 20.0 mL of solution. This value is then multiplied by the molar mass of the compound to determine the mass. The molar mass tells you how many grams are present in one mole of a substance, so multiplying moles by grams per mole cancels the units properly, leaving you with grams.
Among the answer choices provided:
- 1.60 g is correct.
- 40.0 g is incorrect and likely results from using the wrong volume or forgetting to convert units.
- 1.60 kg and 1,600 g are both too large for such a small volume and concentration.
- “More than one of these choices is correct” is false since only 1.60 g is correct.
Therefore, the correct answer is 1.60 g.
