Say I have 50 mL of bromocresol green indicator. This solution has 80mg/L. the molar mass is 698 g/mol.
Then say I took 10 mL of that solution and dilute it with .4 M HCI.
I want to find the concentration/molarity of bromocresol green.
This is what I have attempted to do:
10ml(1L/1000 ml)(1 mol/698g)(1g/1000mg)(80mg/mol)(50mL)(1L/1000 mL)
= 5.73*10^-5 M
Is that even remotely correct?
Doesn't the final concn depends upon the final volume. You tell us you diluted the solution with 0.4 M HCl but to what final volume?
Your attempted calculation appears to have a few errors. Here's the correct step-by-step calculation to determine the concentration (molarity) of bromocresol green:
1. Convert the volume of the initial solution from mL to L:
50 mL * (1 L / 1000 mL) = 0.05 L
2. Calculate the amount of bromocresol green in the initial solution in moles:
0.05 L * (80 mg/L) * (1 g / 1000 mg) * (1 mol / 698 g) = 0.000571 mol
3. Determine the volume of the diluted solution in L:
10 mL * (1 L / 1000 mL) = 0.01 L
4. Calculate the amount of bromocresol green in the diluted solution in moles (assuming no chemical reactions occur):
0.000571 mol * (0.01 L / 0.05 L) = 0.0001142 mol
5. Determine the concentration (molarity) of bromocresol green in the diluted solution:
0.0001142 mol / 0.01 L = 0.01142 M
Therefore, the concentration (molarity) of bromocresol green in the diluted solution is 0.01142 M. Note that this calculation assumes that adding HCl does not react with bromocresol green and cause any changes in concentration.
To find the concentration or molarity of bromocresol green (BCG), you need to consider the dilution factor and the reaction taking place when the solution is mixed with HCl.
First, let's calculate the number of moles of BCG present in the 10 mL of solution you took:
Number of moles of BCG = volume (L) x concentration (mol/L)
= 10 mL x (1L/1000 mL) x (80 mg/L) x (1 g/1000 mg) x (1 mol/698 g)
By performing the above calculations, you will get the number of moles of BCG in the 10 mL solution.
Next, you need to consider the dilution with 0.4 M HCl. The reaction that occurs can be represented as follows:
BCG (aq) + HCl (aq) → BCG-HCl (aq)
Assuming complete reaction, the moles of BCG will be equal to the moles of BCG-HCl after the dilution. Therefore, we can say:
Number of moles of BCG-HCl = Number of moles of BCG
Now, using the dilution formula, which states that the initial moles of solute are equal to the final moles of solute after dilution, we can find the resulting concentration of BCG-HCl:
M1V1 = M2V2
Here, M1 and V1 represent the initial concentration and volume of the BCG-HCl solution, respectively, while M2 and V2 represent the final concentration and volume. We can assume V1 = 10 mL and V2 = (10 mL + V_HCl).
Plugging the values into the formula, we get:
(Number of moles of BCG-HCl)/V2 = (Number of moles of BCG)/V1
Simplifying the equation, we have:
(Number of moles of BCG-HCl) = ((Number of moles of BCG)/V1) × V2
Rearranging, we get:
(Number of moles of BCG-HCl) = ((Number of moles of BCG) × V2)/V1
Now, you can calculate the concentration of BCG-HCl (which is the same as the concentration of BCG) using the equation:
Concentration (Molarity) of BCG = (Number of moles of BCG-HCl)/V2
By performing these calculations, you can find the concentration or molarity of bromocresol green in the final solution.