Concentration of solutions

Chemistry
Tutor: None Selected Time limit: 1 Day

You have 75 mL of a 2.5 M solution of Na2CrO4(aq). You also have 125 mL of a 2.01 M solution of AgNO3(aq). Calculate the concentration of CrO4^2- after the two solutions are mixed together. 

Oct 13th, 2015

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Na2CrO4 & AgNO3 --> Ag2CrO4 & NaNO3 

moles involved in the reaction: 
(0.075 L) x (2.50 mol / L) = 0.1875 moles CrO4-2 
(0.125 L )x (2.37 mol / L) = 0.29625 moles Ag+ 

2 Ag+ reacts with 1 CrO4-2 --> 1 Ag2CrO4 , 
0.296 moles of Ag+ reacts with, 1/2 it, 0.1481 moles CrO4-2 

leaves a-precipitated, 
0.1875 - 0.1481 = 0.0394 moles of CrO4)-2 in the 200 ml of solution 

molarity: 
0.0394 moles of CrO4)-2 / 0.200 litres = 0.197Molar 
0.197Molar (CrO4)-2 

Oct 13th, 2015

Correction:

Na2CrO4 & AgNO3 --> Ag2CrO4 & NaNO3 

moles involved in the reaction: 
(0.075 L) x (2.50 mol / L) = 0.1875 moles CrO4-2 
(0.125 L )x (2.01 mol / L) = 0.25 moles Ag+ 

2 Ag+ reacts with 1 CrO4-2 --> 1 Ag2CrO4 , 
0.25 moles of Ag+ reacts with, 1/2 it, 0.1481 moles CrO4-2 

leaves a-precipitated, 
0.1875 - 0.1481 = 0.0394 moles of CrO4)-2 in the 200 ml of solution 

molarity: 
0.0394 moles of CrO4)-2 / 0.200 litres = 0.197Molar 
0.197Molar (CrO4)-2 

Oct 13th, 2015

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Oct 13th, 2015
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Oct 13th, 2015
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