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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: orgo814 on February 11, 2015, 05:27:24 PM

Title: Solution
Post by: orgo814 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)?
Title: Re: Solution
Post by: Borek on February 11, 2015, 05:54:35 PM: Quote from: butlerw2 on February 11, 2015, 05:27:24 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.
Title: Re: Solution
Post by: orgo814 on February 11, 2015, 06:04:44 PM: 500 x 2?
Title: Re: Solution
Post by: orgo814 on February 11, 2015, 07:45:40 PM: Is that correct? This problem is confusing me
Title: Re: Solution
Post by: Hunter2 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.