Answer:
Molar concentration = [tex]1.4 \times 10^{-9} M[/tex]
Explanation:
Concentration of alkane ([tex]C_{20}H_{42}[/tex] = 0.40 ppb
1 ppb = [tex]10^-3\ mg/L[/tex]
Concentration of alkane ([tex]C_{20}H_{42}[/tex] in mg/L
= [tex]4.00 \times 10^{-4}\ mg/L[/tex]
Concentration of alkane ([tex]C_{20}H_{42}[/tex]) is [tex]4.00 \times 10^{-4}\ mg/L[/tex] that means [tex]4.00 \times 10^{-4}[/tex] is present in 1 L
Density of water = 1.00 g/mL
Molar concentration =[tex]\frac{Mass\ in\ g}{Molar mass \times Volume\ in\ L}[/tex]
Formula weight = 282.55
Mass of [tex]C_{20}H_{42}[/tex] = [tex]4.00 \times 10^{-4}\ mg/L[/tex] = [tex]4.00 \times 10^{-7}\ g/L[/tex]
Here, formula mass is equal to molar mass.
Molar concentration =[tex]\frac{4.00 \times 10^{-7}}{282.55 \times 1} = 1.4 \times 10^{-9} M[/tex]
