5 a water analyst uses nh4k2po4 to prepare standards for nh4...

5. A water analyst uses NH4K2PO4 to prepare standards for NH4+, K and P analyses. (a) What weight of the compound is required to make 1.00 dm3 of a 100 ppm K standard? (b) What volumes of this stock are required to prepare 100 cm3 each of: i a solution containing 10 ppm NH4+, ii a solution containing 25 ppm of P. [Hint for (b): work out first how many moles of salt were dissolved to make the solution in (a); hence for (i) calculate the ppm for NH4+ in the original stock, then use the equation for dilution: (ppm)1xV1 = (ppm)2xV

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00:06 Okay, so 0 .2 grams of solid waste was dissolved in 200 milliliters of water.

00:17 So that equates out to 0 .2 divided by 200 to 0 .00 to 0 .001 grams per millimeter.

00:33 Now, 0 .001 grams per millimeter is equal to 1 ,000 parts per million.

00:55 Okay? so, same thing.

01:04 The next example, 0 .7 grams in 1 ,000 millimeters.

01:09 That's 0 .0007.

01:17 1, 2, 3 grams per milliliter.

01:30 So 0 .007 grams per milliliter is 700 parts per million.

01:43 Okay.

01:44 How would you prepare a 50 -millimeter? stock of 100 parts per million working solution from a 1 ,000 parts per million.

01:56 So we're going to use our trusty formula.

01:59 C1 v1 equals c2, v2.

02:06 So for here, c1 is going to be 1 ,000 parts per million stock.

02:12 V1 is what we're solving for.

02:15 C2 is going to be 100 part per million.

02:20 Per million and c or sorry v2 is going to be 50 milliliters so quickly parts per million can cancel we divide both sides by 1 ,000 so these cancel start canceling zeros so v1 therefore is going to be five milliliters okay okay from a 500 for million stock solution calculate the volume stock solution you take to prepare a series of 50 milliliter standards of 0, 10, 20, 30, and 50 price for 10.

03:16 So literally i'll just do one example.

03:17 You just kind of have to do the rest.

03:20 500...

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