Mohammed H.

asked • 12/06/17

How to modify prepared Seawater chemistry so that Mg/Ca ratio = 1?

I prepared 1 liter of artificial sea water by mixing 1 liter of pure water and 35 grams of "Instant Ocean" salt. According to the recipe, salinity = 35000 ppm, Magnesium (Mg) = 1320 ppm and Calcium (Ca) = 400 ppm. My objective is to modify this sea water so that the Mg/Ca ratio equals 1. Therefore, my first step was to figure out what is the Mg/Ca ratio of the current solution, then the second step is to modify the ratio so it equals 1. My approach was: first part: Mg = 1320 ppm or 1320 mg/Ca Ca = 400 ppm or 400 mg/L Molarity of Mg = 1320/(1000 * 24.305) = 0.054 moles/L Molarity of Ca = 400/(1000* 40.078) = 0.0099 moles/ L Mg/Ca = 0.054/0.0099 = 5.7 Second part: for Mg/Ca = 1, then 0.054/Ca = 1 Ca = 0.054 0.054 = ppm *0.001/40.078 ppm = 2164 or mg/L So i have to add 2164 - 400 = 1764 mg to 1 Liter of water of the solution to get Mg/Ca = 1 My questions are: 1. How i the rationale of my approach(i.e. is this the correct approach? 2. Is it correct to assume that ppm = mg/L, considering that we are dealing with Saline water not Pure so 1 Kg doesnt equal 1 Liter. what is the alternative way?

1 Expert Answer


Mohammed H.

I want to the ratio  to be 1mole/1 mole. Thanks a lot, your answer helped.


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