pepsi brand soft drinks contain 38 mg of caff...
pepsi brand soft drinks contain 38 mg of caffeine (molar mass = 194.19 g/mol) for every serving (355 ml of solution). what is the molarity of caffeine in this solution?\na 5.51×10⁻⁴\nb 6.71×10⁻⁴\nc 4.39×10⁻⁴\nd 4.89×10⁻⁴
Answer
# Explanation:
## Step1: Convert mass to moles
First, convert the mass of caffeine from mg to g. Given 38 mg of caffeine, $38\ mg=38\times10^{- 3}\ g$. Then use the formula $n=\frac{m}{M}$, where $m$ is the mass and $M$ is the molar - mass. So $n=\frac{38\times10^{-3}\ g}{194.19\ g/mol}\approx1.96\times10^{-4}\ mol$.
## Step2: Convert volume to liters
The volume of the solution is $V = 355\ mL$. Convert it to liters: $V=355\ mL = 355\times10^{-3}\ L=0.355\ L$.
## Step3: Calculate molarity
Use the molarity formula $M=\frac{n}{V}$, where $n$ is the number of moles and $V$ is the volume of the solution in liters. So $M=\frac{1.96\times10^{-4}\ mol}{0.355\ L}\approx5.51\times10^{-4}\ mol/L$.
# Answer:
A. $5.51\times10^{-4}$