Answer:
CONCENTRATION IS 0.4 mol/dm3
Explanation:
If 5.85g of table salt, NaCI, are dissolved in water to make a solution of 250ml, what is the concentration of the solution, in mol/dm3 or mol/l?
Mass = 5.85 g
Substance = NaCl
Volume = 250 mL = 0.25 L
Concentration in mol/dm3 = concentration in g/dm3 / Relative Molecular mass
Step 1: calculate the concentration in g/dm3
5.85 g = 0.25 L
(5.85 / 0.25) g = 1 L
Concentration in g/dm3 = 23.4 g/dm3
Step 2: calculate the relative molecular mass of NaCl
(Na= 23, Cl = 35.5)
RMM = (23+ 35.5)
RMM = 58.5 g/mol
Step 3: calculate the concentration in mol/dm3
Conc. in mol/dm3 = Conc. in g/dm3 / RMM
Conc. in mol/dm3 = 23.4 g/dm3 / 58.5 g/mol
Conc. in mol/dm3 = 0.4 mol/dm3
So therefore, the concentration in mol/dm3 of the solution is 0.4 mol/dm3
Answer:
Explanation: 0.4004mol/L
Given
Mass of NaCl = 5.85g
no of moles of NaCL =Mass/ molar mass
but molar mass of NaCl= (22.99 g/mol + 35.45 gmol )= 58.44 g/mol.
therefore, Number of moles= 5.85g/ 58.44g/mol= =0.100 moles
Also, converting 250ml to litres becomes 250/1000= 0.25L
Concentration of the solution in mol /L =
Concentration = number of moles of solutes/ total volume of solution
therefore C= n/v= 0.100moles/ 0.25L = 0.4004mol/L
