The density of 2-methyl-2-butanol is 0.806 g/mL. How many mgs represent an aliquot of 430 ML? How many mmols represent an aliquot of 0.650 mL (2-methyl-2-butanol, formula weight is 88.15 g/mol)?
The Correct Answer and Explanation is :
Answer:
- Mass of 2-methyl-2-butanol in an aliquot of 430 mL: [
\text{Density} = \frac{\text{Mass}}{\text{Volume}} \quad \text{so, Mass} = \text{Density} \times \text{Volume}
]
[
\text{Mass} = 0.806 \, \text{g/mL} \times 430 \, \text{mL} = 346.58 \, \text{g}
]
Converting to milligrams:
[
346.58 \, \text{g} \times 1000 \, \text{mg/g} = 346,580 \, \text{mg}
]
Answer: 346,580 mg - Moles of 2-methyl-2-butanol in an aliquot of 0.650 mL: First, calculate the mass of 0.650 mL of 2-methyl-2-butanol:
[
\text{Mass} = 0.806 \, \text{g/mL} \times 0.650 \, \text{mL} = 0.5239 \, \text{g}
]
Convert to moles using the formula weight ((88.15 \, \text{g/mol})):
[
\text{Moles} = \frac{\text{Mass}}{\text{Formula weight}} = \frac{0.5239 \, \text{g}}{88.15 \, \text{g/mol}} = 0.00594 \, \text{mol}
]
Converting to millimoles:
[
0.00594 \, \text{mol} \times 1000 \, \text{mmol/mol} = 5.94 \, \text{mmol}
]
Answer: 5.94 mmol
Explanation:
- Density and Volume Relationship:
Density connects the mass of a substance to its volume. By multiplying the density (( \text{g/mL} )) by the volume (( \text{mL} )), the mass (( \text{g} )) can be calculated. This is crucial for determining how much substance (by weight) is in a given volume. - Conversion to Milligrams:
Since the question asks for milligrams, grams are converted to milligrams by multiplying by 1000 ((1 \, \text{g} = 1000 \, \text{mg})). - Moles and Formula Weight:
To calculate the number of moles of a substance, the mass is divided by its molecular weight (formula weight, ( \text{g/mol} )). For smaller quantities, millimoles (( \text{mmol} )) are used, which is equivalent to multiplying the moles by 1000. - Practical Application:
Such calculations are commonly used in chemistry and biochemistry for preparing solutions and understanding reactant quantities in reactions, ensuring precise experimental results.