Use a balanced redox equation to answer the following question.
71.7 mL of 1.13 x 10-4 mol L-1 potassium ferricyanide solution is required to react completely with 43.9 mL of ascorbic acid solution (under acidic conditions).
What is the concentration of the ascorbic acid solution, in μmol L-1 ?
Would someone please just help me balance the equation??
2 ferricyanide + ascorbic acid ==> 2 ferrocyanide + 2H^+ + dehydroascorbic acid
To balance the redox equation, we first need to identify the reactants and products involved. From the given information, we know that potassium ferricyanide (K3Fe(CN)6) is reacting with ascorbic acid (C6H8O6) under acidic conditions.
The unbalanced equation can be represented as follows:
C6H8O6 + K3Fe(CN)6 → ??
To balance the equation, we need to determine the oxidation states of the elements involved. In this case, we see that potassium (K) and cyanide (CN) remain unchanged in the reaction. Therefore, we can omit them for the purpose of balancing the equation.
Now, let's balance the equation step by step:
1. Balance the atoms and charges for each element separately:
C6H8O6 + K3Fe(CN)6 → C6H8O6 + ??
2. Balance the atoms and charges for each half-reaction separately.
First, we'll balance the reduction half-reaction. We know that Fe (in K3Fe(CN)6) is being reduced. The reduction half-reaction is:
Fe3+ → Fe2+
3. Balance the atoms and charges for the oxidation half-reaction:
C6H8O6 → ??
To balance the oxidation half-reaction, we need to determine the oxidation states of carbon in C6H8O6. Carbon has a -4 oxidation state in ascorbic acid. So, the balanced oxidation half-reaction is:
C6H8O6 → 6CO2
4. Combine the two half-reactions together:
Fe3+ + C6H8O6 → Fe2+ + 6CO2
5. Balance the number of electrons transferred between the two half-reactions by adding appropriate coefficients:
2Fe3+ + 3C6H8O6 → 2Fe2+ + 6CO2
Now that the equation is balanced, we can proceed to solve the problem.
To balance the equation, we need to first determine the chemical formula for potassium ferricyanide and ascorbic acid.
The chemical formula for potassium ferricyanide is K3[Fe(CN)6], and the chemical formula for ascorbic acid is C6H8O6.
The balanced redox equation for the reaction between potassium ferricyanide and ascorbic acid under acidic conditions can be written as:
C6H8O6 + K3[Fe(CN)6] -> H2O + 6CO2 + 3K+ + 3Fe2+ + 6CN-
Now that we have the balanced equation, we can proceed to solve the problem.
Step 1: Calculate the number of moles of potassium ferricyanide (K3[Fe(CN)6]).
Molarity of potassium ferricyanide solution = 1.13 x 10^-4 mol L^-1
Volume of potassium ferricyanide solution = 71.7 mL = 0.0717 L
Number of moles of potassium ferricyanide (K3[Fe(CN)6]) = Molarity x Volume
= (1.13 x 10^-4 mol L^-1) x (0.0717 L)
= 8.128 x 10^-6 mol
Step 2: Since the stoichiometric ratio between potassium ferricyanide and ascorbic acid is 1:1, the number of moles of ascorbic acid is also 8.128 x 10^-6 mol.
Step 3: Calculate the concentration of ascorbic acid in μmol L^-1.
Volume of ascorbic acid solution = 43.9 mL = 0.0439 L
Concentration of ascorbic acid = (Number of moles of ascorbic acid / Volume of ascorbic acid solution) x 10^6
= (8.128 x 10^-6 mol / 0.0439 L) x 10^6
≈ 185.34 μmol L^-1
Therefore, the concentration of the ascorbic acid solution is approximately 185.34 μmol L^-1.