Question 15 of 15 Map A Sapling Learning 263 g of Na2Cro4 (Mw 161.97 g/mol) is d

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Question 15 of 15 Map A Sapling Learning 263 g of Na2Cro4 (Mw 161.97 g/mol) is dissolved in 1000.0 m of water. Assuming the solution has a density of 1.00 g/mL, what is the concentration of Na (MW 22.9898 g/mol) in the solution in units of a) molarity (M)? Number M. b) parts per thousand (ppt? Number ppt c) 10.0 mL of the solution is then diluted to a final volume of 500.0 mL. What is the concentration of Na in the diluted solution in units of parts per million (ppm)? Number ppm O Previous ® Give Up & View Solution Check Answer Next H Ext Hint

Explanation / Answer

molarity = moles / V in L

Moles = mass / Molar mass

Volume = 1000 ml = 1 litre

Molarity = Mass / Molar mass*V in L = 6263 / 161.97*1 = 38.66 M

[Na2CrO4 ] = 38.66 M

Na2CrO4 ------> 2Na+ + CrO4-2

[Na+] = 2*38.66 = 77.32 M

b]

ppt = 1 g/L

ppt of Na+ = 77.32*22.9898 = 1777.57 ppt

c]

M1V1 = M2V2

77.32*10 = M2*500

M2 = 1.5464 mol/litrre

In ppm = 1mg /L

===> 1.5464*22.9898*1000 = 35551.42 ppm

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