e) 0.0613 g The EPA has set the maximum level of As in drinking water as 1.3x 10
ID: 577116 • Letter: E
Question
e) 0.0613 g The EPA has set the maximum level of As in drinking water as 1.3x 10 a) 1.3 x 10-10 ppm M. What is the As level in ppm? b) 1.7x 10 ppm c) 9.7x 10 ppm d) 1.7 x 10-2 ppm e) 9.7x 10 ppm 9. What t is the molar concentration of Na in a solution prepared by dissolving 100.0g of Na POs in sufficient H:O to form 2.00 L of solution? a) 0.305 M b) 0.0101 M c) 0.91S M d) 3.86 M e) 1.22 M 10. How many moles of sodium phosphite are required to prepare 23.6 ml of 0.0574 M Na PO? 5.74×10-2 moles NasPO 1.35×10", moles NaPO, a) b) c) 8.49 x 10° moles Na PO 2.00×10-1 moles NaP03 9.16×10)moles NaP0i d) e) 11. What is the concentration of potassium nitrate in a solution prepared by dissolving 8.14e-3 moles of KNO, in 85.0 mL of water? a) 9.58×105 M KNO3 b) 9.68 M KNO, ) 9.58 102 MKNO, d) 6.92 x 10- M KNO e) 9.68 × 10' M KNO3 What is the concentration of chloride ions in 59.6 mL of 0.716 MSrC1? a) 0.716 MCH b) 0.358 MCI c) 0.477 MCI d) 1.43 MCI e) 85.3 MC 12. 13. What is the concentration of Na SO4 in a solution that is 0.469 M in Na? a) 0.704 M Na SO b) 0.469 M Na SO c) 0.938 M Na SO4 d) 0.313 M Na SO e) 0.235 M Na S0 How many moles of cesium fluoride are required to prepare 89.6 ml of 0.666 M CsF? a) 14. 0.0597 moles CsFExplanation / Answer
(8)
MW of Arsenic, As = 75 g
Also,
1 ppm = 1 mg/L
So,
Given conc = 1.3*10-7 M = 1.3*10-7 moles/L = 1.3*10-7*75 g/L = 1.3*10-7*75*1000 mg/L = 9.7*10-3 ppm
(9)
Moles of solute in the solution = Mass/MW= 100/164 = 0.609
Molarity = Moles/Volume in liters = 0.609/2 = 0.3045 M
Since 1 mole of solute produces 3 moles of Na+ ions, so molar conc of Na+ ions = 0.3045*3 = 0.915 M
(10)
Using the relation:
Molarity = Moles/Volume in liters
So,
Moles = Molarity*Volume in liters = 0.0574*23.6*10-3 = 1.35*10-3 moles
Hope this helps !
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