Question

What would be the final ppm of F- in thes five stock solutions, as shown in the last row.

Preparation of Standards 1. To a clean 250 mL beaker, add 70 mL T.I.S.A.B and 70 mL distilled water. Mix well. 2. 10.0 ppm and 1.00 ppm fluoride standard solutions are provided. Obtain and label five clean 25 mL volumetric flasks. Prepare the standards according to the table below. Flasks 4. F standards, mL 10.0 (10.0 ppm) 5.0 (10.0 ppm) |2.5 (10 ppm) 10.0 (1.0 ppm) 5.0 1.0 ppm) L of above T.I.S.A.B dilute to mark dilute to mark dilute to mark dilute to mark dilute to mark (prepared in step 1) Final ppm of F

Answer 1

Final solutions vol is 25 mL For Flask - 1 m_1 v_1 = m_2 v_2 implies 10 ppm items 10 mL = m_2 times 25 mL v_2 implies Final value implies m_2 = 10 times 10/25 = 100/25 = 4 ppm Flesh -2 10 times 5 mL = m_2 times 25mL implies m = 10 times 5/25 = 2ppm Flash - 5 10 ppm times 2.5 mL = m_2 times 25 mL implies m_2 = 10 times 2.5/25 = 25/25 = 1ppm Flash - 4 1 ppm times 10mL = m_2 times 25mL implies m_2 = 1 times 10/25 = 0.4 ppm Flesh - 5 1 ppm times 5 mL = m_2 times 25 implies m_2 = 5/25 = 0.2 ppm