In: Chemistry
How do I prepare a 10ml mixture of 0.0200M Cr(NO3)3 and 0.0752M Co(NO3)2 if I have a stock solution of 25ml of 0.0500M Cr(NO3)3 and another stock solution of 25ml of 0.1880M Co(NO3)2?
Total volume of the mixture to be prepared, Vt = 10 mL
Given the concentration of Cr(NO3)3 in the mixture = 0.0200 M
Hence millimoles of Cr(NO3)3 in the mixture = Volume x concentration = 10 mL x 0.0200M = 0.200 millimol
Given the concentration of Co(NO3)2 in the mixture = 0.0752M
Hence millimoles of Co(NO3)2 in the mixture = Volume x concentration = 10 mL x 0.0752M = 0.752 millimol
Let the volume of Cr(NO3)3 taken from 0.0500M Cr(NO3)3 stock solution be 'V' mL
Hence millimoles of Cr(NO3)3 taken from stock solution = millimoles of Cr(NO3)3 in the mixture
=> V mL x 0.0500M = 0.200 millimol
=> V = 0.200 millimol / 0.0500M = 4 mL
Hence volume of 0.0500M Cr(NO3)3 required from stock solution = 4 mL
Hence volume of 0.1880M Co(NO3)2 required = Vt - 4 mL = 10 mL - 4 mL = 6 mL
Hence we need to add 4 mL of 0.0500M Cr(NO3)3 stock solution and 6 mL of 0.1880M Co(NO3)2 stock solution to prepare the mixture. (answer)