To calculate the molar concentration \( C \) of the riboflavin solution, we can use the formula:
\[ C = \frac{n}{V} \]
where:
- \( n \) is the number of moles of riboflavin,
- \( V \) is the volume of the solution in liters.
Step 1: Convert mass from mg to grams.
Given mass of riboflavin = \( 1.1 \times 10^2 \) mg
\[ 1.1 \times 10^2 , \text{mg} = 110 , \text{mg} = 110 \times 10^{-3} , \text{g} = 0.110 , \text{g} \]
Step 2: Calculate the number of moles of riboflavin.
The number of moles \( n \) can be calculated with the formula:
\[ n = \frac{\text{mass}}{\text{molar mass}} \]
Substituting the values:
\[ n = \frac{0.110 , \text{g}}{376.37 , \text{g/mol}} \approx 0.000292 , \text{mol} \]
Step 3: Convert volume from mL to liters.
Given volume = \( 6.500 \times 10^2 \) mL
\[ 6.500 \times 10^2 , \text{mL} = 650.0 , \text{mL} = 650.0 \times 10^{-3} , \text{L} = 0.6500 , \text{L} \]
Step 4: Calculate the molar concentration \( C \).
Now we can use the number of moles and volume to find the concentration:
\[ C = \frac{n}{V} = \frac{0.000292 , \text{mol}}{0.6500 , \text{L}} \approx 0.000449 , \text{mol/L} , \text{or} , 0.449 , \text{mM} \]
Thus, the molar concentration of the riboflavin solution is approximately:
\[ \boxed{0.000449 , \text{mol/L}} , \text{or} , \boxed{0.449 , \text{mM}} \]
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