calculate the concentration of borate ion for a titration when 6.0998g borax is dissolved in 100mL of water and titrated with 25.5mL of HCl
mols borax = grams/molar mass Na2B4O7*10H2O
mols borate ion = 2x that
M borate ion = mols/0.125L = ?
Here is a link that gives the titration details.
http://en.wikipedia.org/wiki/Borax
To calculate the concentration of borate ion (BO3^2-) in the titration, you'll need to use the stoichiometry of the reaction between borax (Na2B4O7) and HCl.
The balanced equation for the reaction is:
Na2B4O7 + 2HCl -> 2NaCl + 4H3BO3
1. Calculate the number of moles of HCl used in the titration:
- 25.5 mL HCl * (1 L / 1000 mL) * (x mol / 1 L) = x mol HCl
(Note: x represents the number of moles of HCl used)
2. Use stoichiometry to find the number of moles of borax (Na2B4O7) reacting:
- From the balanced equation, it's clear that 2 moles of HCl react with 1 mole of Na2B4O7
- So, 2 * x mol of Na2B4O7 react with x mol of HCl
3. Calculate the number of moles of borax (Na2B4O7) in your initial solution:
- 6.0998 g Na2B4O7 * (1 mol / molar mass of Na2B4O7) = y mol Na2B4O7
(Note: y represents the number of moles of Na2B4O7)
4. Use the molar ratio from the balanced equation to calculate the number of moles of borate ion produced:
- From the balanced equation, it's clear that 1 mole of Na2B4O7 produces 4 moles of H3BO3
- So, y mol Na2B4O7 will produce 4 * y mol of H3BO3
5. Calculate the concentration of borate ion (H3BO3):
- Concentration = (number of moles of H3BO3) / (volume of solution used for titration)
- Volume of solution used for titration = 100 mL
- Concentration = (4 * y mol) / (100 mL) * (1000 mL / 1 L)
- Simplifying the units, Concentration = (4 * y) / 1 L
Now you have the concentration of borate ion in moles per liter.
To calculate the concentration of borate ion for a titration, we need to determine the number of moles of borax and HCl involved in the reaction.
Step 1: Calculate the number of moles of borax (Na2B4O7·10H2O):
First, determine the molar mass of borax.
Molar mass of B = 10.81 g/mol
Molar mass of O = 16.00 g/mol
Molar mass of Na = 22.99 g/mol
Molar mass of H = 1.01 g/mol
Molar mass of Na2B4O7·10H2O:
(2 * molar mass of Na) + (4 * molar mass of B) + (14 * molar mass of O) + (20 * molar mass of H)
= (2 * 22.99 g/mol) + (4 * 10.81 g/mol) + (14 * 16.00 g/mol) + (20 * 1.01 g/mol)
= 22.99 + 43.24 + 224.00 + 20.20
= 310.43 g/mol
Next, calculate the number of moles of borax:
Number of moles = mass / molar mass
Mass of borax = 6.0998 g
Number of moles of borax = 6.0998 g / 310.43 g/mol
Step 2: Calculate the number of moles of HCl:
The reaction between borax and HCl is:
Na2B4O7 + 2HCl → 2NaCl + 4H3BO3
From the balanced equation, we can see that each mole of borax reacts with 2 moles of HCl. Since we have the volume of HCl used, we need to determine its concentration to find the number of moles.
Step 3: Calculate the concentration of HCl:
Concentration = number of moles / volume
Given the volume of HCl is 25.5 mL, we need to convert it to liters:
Volume of HCl = 25.5 mL = 25.5 / 1000 L
Now we have all the necessary information to calculate the concentration of HCl.
Step 4: Calculate the concentration of borate ion:
The reaction ratio states that each mole of borax reacts with two moles of HCl. Therefore, the number of moles of HCl that reacted with all the borax can be determined by:
Number of moles of HCl = 2 * number of moles of borax
Finally, the concentration of borate ion can be calculated:
Concentration of borate ion = number of moles of borate ion / volume of HCl
By following these steps and plugging in the given values, you should be able to calculate the concentration of borate ion for the titration.