15 cm³ of ethanoic acid was dissolved in water to make 500cm³ of solution. Calculate the concentration of the solution in moles per litre (C=12, H=1, O=16, density of ethanoic acid is 1.05g/cm³)

Step 1: Calculate the mass of ethanol acid.
Formula:
$mass = V \times \rho$
Substitute:
$mass = 20 \, mL \times 1.05 \, \frac{g}{mL} = 21 \, g$

Step 2: Calculate the number of moles of ethanol acid.
Formula:
$n = \frac{mass}{M_r}$
Substitute:
$n = \frac{21 \, g}{60 \, \frac{g}{mol}} = 0.35 \, mol$

Step 3: Convert the volume of solution to liters.
$V = 500 \, mL = 0.500 \, L$

Step 4: Calculate the concentration of the solution.
Formula:
$c = \frac{n}{V}$
Substitute:
$c = \frac{0.35 \, mol}{0.500 \, L} = 0.70 \, \frac{mol}{L}$

0.70 M