2. Make a dilution of the 3.5% NaCl stock solution by adding 1 mL of the 3.5% so

Question

2. Make a dilution of the 3.5% NaCl stock solution by adding 1 mL of the 3.5% solution to 9.0 ml., of water in a test tube. Label this test tube as 0.35%. Seal the test tube with a piece of parafilm and invert the test tube several times to mix the contents. dilution of 3.5% NaCl x 3.5% 0.35% NaCl 3. Make a 1/25 dilution of the 0.35% NaCl solution by placing 2 ml of the 0.35% NaCl solution into a 100-mL pour beaker and use a 50-ml graduated cylinder to add 48 ml of H2O to the beaker. Add a parafilm seal and swirl the beaker to mix the contents ml NaCl What is the concentration of this solution?

Explanation / Answer

(a) 0.35% NaCl means 0.35g in 100 ml

i.e. 3.5 mg per ml

therefore 3500 ug/ml

(b) apply the formula n1v1=n2v2

where n1=0.35, v1=2, n2=? & v2=50

then the solution is 0.014%

Now calculate like part (a), then the solution is found to be 140ug/ml

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