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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: JimiGreen on October 21, 2014, 07:38:33 AM

Title: PPM (w/w, v/v, or n/n) Colgate example
Post by: JimiGreen on October 21, 2014, 07:38:33 AM

Hello everyone,

This will be my first post on this forum, but hopefully (?) the first of many, chemistry really is fascinating. I'm not in high school anymore but since this is an easy question I posted it in this subsection.

I was looking for a datasheet on sodium fluoride but my attention wandered and I found a link for a tooth paste, which claims to be a 1.1% w/w paste for fluoride (as sodium fluoride). But then they mention that it's also 5000ppm. What is going on here? Since the latter equals to 5mg per g of tooth paste and the former 11mg (if my calculations are correct). 

Maybe their 5000ppm is not a w/w but something else, however I doubt it since they also show the same calculation (5mg/g). Maybe I am interpreting their 1.1%w/w wrongly?

Thanks in advance.

PS: Here is the link http://www.colgateprofessional.co.uk/products/Colgate-Duraphat-5000ppm-Fluoride-Toothpaste/specifics

Title: Re: PPM (w/w, v/v, or n/n) Colgate example
Post by: Arkcon on October 21, 2014, 08:20:16 AM

I'm at work right now, and can't do the math for you just now.  However, is the 5000 ppm a fluoride content?  A 1.1% sodium fluoride could yield 5000 ppm fluoride.  A quick calc, based on the molecular weight, should satisfy for a yes or no, and we can go from there.

Title: Re: PPM (w/w, v/v, or n/n) Colgate example
Post by: Corribus on October 21, 2014, 09:53:29 AM

Yes, 1.1% w/w NaF is equal to ~0.5% w/w fluoride.