What is the number of moles of NaHCO3in 250cm3 of its solution if the solution contains 8.4 g of NaHCO3 in 1 dm3 of the solution. [Na = 23, 0 = 16, C = 12, H = 1)
- 1
- 0.25
- 0.05
-
0.025
- 0.01
The correct answer is: D
Explanation
no of mole in 250\(cm^3\) of its solution is about molar concentration.
using n = cv
c = \(\frac{n}{v}\)
where c = molar concentration, n = number of moles and v = volume in \(dm^3\)
number of mole of NaHCO3 = mass of NaHCO3 / molar mass of NaHCO3 = \(\frac{8.4}{84}\) = 0.1moles
but v = 250\(cm^3\) = 250/1000 = 0.25\(dm^3\)
therefore c = 0.25 x 0.1 = 0.025mol\(dm^3\)