1) A buffer solution was made by adding 6.56g of sodium ethanoate to 1dm3 of 0.02moldm-3 ethanoic acid.
a) What is the concentration of the sodium ethanoate?
b)What is the concentration of the ethanoic acid?
CH3COONa = NaAc = base
CH3COOH = HAc = acid
(NaAc) = 0.56 g/molar mass/1L
(HAc) = 0.02 M from the problem. Post your work if you get stuck.
Wouldn't the concentration for CH3COONa be:
6.56 g /82 gmol-1 /1.00656 L
To find the concentration of the sodium ethanoate and the ethanoic acid, we need to use the equation:
Molarity (M) = moles of solute / volume of solution (in dm³)
First, let's calculate the moles of sodium ethanoate:
a) Moles of sodium ethanoate:
Moles = mass / molar mass
Molar mass of sodium ethanoate (CH3COONa) = 82.03 g/mol
Moles = 6.56 g / 82.03 g/mol
Moles = 0.080 mol
Now, let's calculate the concentration of sodium ethanoate:
Molarity (NaCH3COO) = moles / volume of solution
Molarity (NaCH3COO) = 0.080 mol / 1 dm³
Molarity (NaCH3COO) = 0.080 M (or mol/dm³)
b) Now, let's calculate the concentration of ethanoic acid:
The initial concentration of ethanoic acid is given as 0.02 mol/dm³.
Since no reaction occurs between sodium ethanoate and ethanoic acid, the concentration of ethanoic acid remains unchanged.
Therefore, the concentration of ethanoic acid is 0.02 mol/dm³.
To find the concentration of the sodium ethanoate, you can use the formula:
Concentration (in mol/dm³) = Amount of solute (in g) / Molar mass of solute (in g/mol)
a) First, we need to find the molar mass of sodium ethanoate (CH3COONa). It consists of carbon (C), hydrogen (H), oxygen (O), and sodium (Na).
Molar mass of carbon (C) = 12.01 g/mol
Molar mass of hydrogen (H) = 1.01 g/mol
Molar mass of oxygen (O) = 16.00 g/mol
Molar mass of sodium (Na) = 22.99 g/mol
Therefore, the molar mass of sodium ethanoate is:
(2 × molar mass of carbon) + (4 × molar mass of hydrogen) + molar mass of oxygen + molar mass of sodium
= (2 × 12.01 g/mol) + (4 × 1.01 g/mol) + 16.00 g/mol + 22.99 g/mol
Calculate the molar mass of sodium ethanoate using the formula above.
Once you have the molar mass of sodium ethanoate, you can use the formula mentioned earlier to calculate its concentration. Divide the mass of sodium ethanoate (6.56 g) by its molar mass (in g/mol) and convert the volume of the solution to dm³:
Concentration (of sodium ethanoate) = 6.56 g / (molar mass of sodium ethanoate in g/mol) / 1 dm³
b) To find the concentration of the ethanoic acid, we need to use the formula:
Concentration (in mol/dm³) = Number of moles / Volume (in dm³)
In this case, the number of moles of ethanoic acid is equal to the number of moles of sodium ethanoate because they react in a 1:1 ratio according to the equation:
CH3COOH + CH3COONa ↔ CH3COO⁻ + CH3COOH
The total volume of the buffer solution is given as 1 dm³. Therefore, the concentration of the ethanoic acid is equal to the concentration of the sodium ethanoate.