24.60 of a solution A contain H2SO4 acid is titrated against 25cm^3 portion of solution B containing 1.4g of KOH per 250cm^3 calculate the: 1).concentration of B in mol/dm^3
2). concentration of A in mol/dm^3
(a)
250cm^3=1.4g
1000cm^3=??
=1000/250×1.4
=5.6g/dm^3
molarity=concentration(g/dm^3)/ RFM
RFM of KOH=39+16+1=56
Molarity=5.6/56
=0.1M=0.1mol/dm^3
(b)
H2SO4(aq)+ 2KOH(aq)> K2SO4(aq)+ 2H2O(l)
moles of 25cm^3 of KOH=25/1000×0.1
=0.0025 moles
mole ratio of KOH to H2SO4 is 2:1, thus no of moles of H2SO4= 1/2×0.0025= 0.00125 moles
molarity= 0.00125/0.0246
=0.05081M =0.0508mol/dm^3
moles KOH = grams/molar mass = 1.4/40 = 0.035
molarity KOH = moles/dm3 = 0.035/0.250 = 0.14 M
I assume that 24.60 is 24.60 mL.
H2SO4 + 2NaOH --> Na2SO4 + 2H2O
moles NaOH used = M x dm3 = 0.14 x 0.025 = 0.0035
mols H2SO4 = mols NaOH x 1/2 = 0.0035/2 = 0.00175
M H2SO4 in moles/dm3 = 0.00175/0.0246 = ?
oops. My calculation is for NaOH and not KOH. My bad.
To find the concentration of solution B in mol/dm^3, we need to know the number of moles of KOH in the given 25cm^3 portion.
1) Number of moles of KOH in solution B:
To calculate the number of moles, we can use the formula:
moles = mass / molar mass
The molar mass of KOH is:
K (39.10 g/mol) + O (16.00 g/mol) + H (1.01 g/mol) = 56.11 g/mol
Given:
Mass of KOH = 1.4g
Molar mass of KOH = 56.11 g/mol
moles of KOH = 1.4g / 56.11 g/mol
Now, let's calculate the concentration of B in mol/dm^3 (Molarity).
2) Concentration of B in mol/dm^3:
Molarity (M) = moles / volume (in dm^3)
Given:
Volume of solution B = 25cm^3 = 25/1000 dm^3 = 0.025 dm^3
Concentration of B = moles of KOH / volume of B in dm^3
Now substitute the values we calculated earlier:
Concentration of B = (1.4g / 56.11 g/mol) / 0.025 dm^3
Simplify the equation:
Concentration of B = (0.0249 mol) / 0.025 dm^3
Concentration of B = 0.996 mol/dm^3 (rounded to three decimal places)
To find the concentration of solution A in mol/dm^3, we need to use the balanced chemical equation for the reaction between H2SO4 and KOH. However, the equation is not provided in the question, so it is not possible to calculate the concentration of A without additional information.