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Topic: Solution  (Read 1787 times)

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Offline orgo814

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Solution
« on: February 11, 2015, 05:27:24 PM »
"The molecular weight of sodium chloride is 58.5 g/mol. How many grams of NaCl do you need to dissolve in 1.00 L of water to make a solution that is 500 ppm Na+?

Would you simply do:

500ppm = mg/1.0 L = 500 mg Na+

NaCl freely dissociates to Na+ and Cl- in a 1:1 ratio so would it also be 500 mg NaCl (0.5 grams)?

Offline Borek

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Re: Solution
« Reply #1 on: February 11, 2015, 05:54:35 PM »
NaCl freely dissociates to Na+ and Cl- in a 1:1 ratio so would it also be 500 mg NaCl (0.5 grams)?

500 mg of NaCl doesn't contain 500 mg of Na.
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Offline orgo814

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Re: Solution
« Reply #2 on: February 11, 2015, 06:04:44 PM »
500 x 2?

Offline orgo814

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Re: Solution
« Reply #3 on: February 11, 2015, 07:45:40 PM »
Is that correct? This problem is confusing me

Offline Hunter2

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Re: Solution
« Reply #4 on: February 12, 2015, 01:13:42 AM »
No. You have to convert your mass of NaCl in mole and then backwards calculate the mass of Na.

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