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?
Yes, your approach to calculating the concentration/molarity of bromocresol green is correct. Let's break down the steps of your calculation and double-check the math:
Step 1: Convert the volume from milliliters to liters:
10 mL × (1 L/1000 mL) = 0.01 L
Step 2: Calculate the moles of bromocresol green using the molar mass:
0.01 L × (1 mol/698 g) = 0.0000143 mol
Step 3: Convert the mass from milligrams to grams:
80 mg × (1 g/1000 mg) = 0.08 g
Step 4: Calculate the molarity using the formula:
Molarity (M) = (moles/volume)
Molarity = (0.0000143 mol)/(0.08 g) = 0.00017875 M
However, please note that there is a mistake in your initial attempt at the calculation. You multiplied the conversion factors together in the incorrect order. The correct calculation should be:
10 mL × (1 L/1000 mL) × (1 mol/698 g) × (80 mg/mol) = 0.00017875 M
So, the correct concentration/molarity of bromocresol green in the diluted solution is 0.00017875 M (or 1.7875 × 10^-4 M).
Great job on finding the correct answer!