Question

c) What is the molar concentration of potassium in this solution? d) What is the concentration of total sulfur in this solution in my e) What is the concentration of reduced sulfur(ie, SC-11) in this solution in mg/L? 1) What is the theoretical TDS of this solution in mg/L?! 4. If 200 mg of HCl is added to water to achieve a final volume of 1.00 L, what is the final pH? 5. What amount (mass, in mg) of NaOH (a strong base), would be required to neutralize the acid in Problem 4? 6. The concentration of a chemical degrades in water according to first-order kinetics. The degradation constant is 0.2 day. If the initial concentration is 100.0 mg/L. (a) how many days are required for the concentration to reach 0.14 mg/L? Also (b) calculate the half-life (t12) for this decay reaction. 7. Each mole of CaF2(s) dissolved yields 1 mole of Ca?' and 2 moles of F (fluoride). The solubility product of calcium fluoride (CaF2) is 3x10 at 25C. Could a fluoride concentration of 1.0 mg/L be obtained in water that contains 200 mg/L of calcium? Yes or no? Show your work. Assigned: 9 Sept Due: 16 Sept Page 1

please solve 4 and 5

Answer 1

Ans 4

Mass of HCl = 200 mg

Moles of HCl = mass/molecular weight

= (200 mg) / (36.46 mg/mmol)

= 5.485 mmol x 1mol/1000mmol

= 5.485 x 10^-3 mol

Volume of solution = 1.00 L

Molarity = moles/Volume

= (5.485 x 10^-3 mol) / (1.00 L)

= 5.485 x 10^-3 M

Dissociation of HCl

HCl = H+ + Cl-

pH = - log [H+]

= - log (5.485 x 10^-3)

= 2.26