Outline 1 (Molarity,solutions, Dilutions) #25

Moderators: Chem_Mod, Chem_Admin

BrendaC_1F
Posts: 3
Joined: Wed Nov 16, 2016 3:04 am

Outline 1 (Molarity,solutions, Dilutions) #25

Postby BrendaC_1F » Tue Apr 10, 2018 9:16 pm

5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentration of the solution in the 2nd flask? Molar Masses: K (39.10 g/mol), Mn (54.94 g/mol), O (16.00 g/mol)



A. 2.43 x 10-2 mol.L-1

B. 16.9 mol.L-1

C. 8.43 x 10-2 mol.L-1

D. 1.69 x 10-2 mol.L-1



Can someone walk me through the steps on how to do this please. Thank you!

Patience Olsen 1A
Posts: 28
Joined: Fri Apr 06, 2018 11:04 am

Re: Outline 1 (Molarity,solutions, Dilutions) #25

Postby Patience Olsen 1A » Tue Apr 10, 2018 11:29 pm

Find molarity (M) of the original solution:
5.00 g KMnO4/0.15000 L soln * 1 mol KMnO4/158.04 g KMnO4 = 0.211 mol/L = 0.211 M

Find how many moles of KMnO4 are present in 20.00 mL of this solution using molarity from previous step:
0.211 mol/L * 0.02000 L = 0.00422 mol KMnO4

Find molarity of the new solution using number of moles from previous step:
0.00422 mol/0.25000 L = 0.0169 M

answer is D

BrendaC_1F
Posts: 3
Joined: Wed Nov 16, 2016 3:04 am

Re: Outline 1 (Molarity,solutions, Dilutions) #25

Postby BrendaC_1F » Wed Apr 11, 2018 12:17 am

Thank you so much. That cleared things up.


Return to “Molarity, Solutions, Dilutions”

Who is online

Users browsing this forum: No registered users and 1 guest