Potassium in II8 Pre-la b Worksheet Determination of Sodium and : attach Amounts

Question

Potassium in II8 Pre-la b Worksheet Determination of Sodium and : attach Amounts by Flame Photometry Read the experiment, and then answer the following questions additional pages as needed as needed n ansiwer the following questions. Show all alculations; at at contains Nasses of NaCI and KCI that are required to prepare 250.0 ml of a standard that contains Na and K, each present at 1000 ppm wn Calculate the masses of NaCI and KCI that are requi red to prepare 1. are required to prepare 250 2. Calculate the amount (mL) of 1000 ppm wiv Na/K needed to prepare 250 mL of 100 ppm w/v Na/K. 3. Calculate how many ml of 100 ppm w'v Na/K are needed to prepare 100 mlL cach of standards containing 1, 2, 3, 4 and 5 ppm w/v Na and K 33 a Calculate the Na and K+ concentrations ifyou used 0.8500 goKe instead of the values you calculated in Question 1, to prepare 250 mL of solution. What then 4. would be the concentrations of the diluted solutions in Questions 2 and 37 tn the theory behind how flame photometry is us s. Briefly explain the theory behind how flame photometry is used to measure Na" and K ter sample containing several difllerent metals at v If a river water sample contai through the flame photometer, how can wbetetals at being measured and not any other metal?e fertain thar g concentrations only one element, such as 6. in that is put Na, is

Explanation / Answer

1. sodium and potassium 1000ppm (w/v) = 1g / L

thus sodium should be one gram in one L

or 0.25 gram in 250mL

In 58.5 g of NaCl = 23 g of sodium is present

so for 1 gram we will need 2.54 gram of NaCl

so for 0.25 gram we will need 0.63 gram of NaCl in 250mL

In 74.5 gram of KCl we have 39 gram of potassius

so for one gram of potassium we need 1.91 gram of KCl

so for 0.25 gram of potassium we need 0.4775 gram of KCl in 250mL

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