Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: orgo814 on February 23, 2015, 07:03:26 PM

Title: Concentration and mass
Post by: orgo814 on February 23, 2015, 07:03:26 PM

"The concentration of potassium in a 5.0 ounce banana is 220 ppm. What mass of potassium chloride would you have to ingest to get the same amount of potassium as the banana contains. K = 39 g/mol, Cl = 35.5 g/mol"

5 oz = 141.875 grams. Then 220 ppm x 142.875 g = 31212.5 ug

0.0312125 g x (1mol/39 g) ( 35.5 g/mol) = 0.0284 g

Is this correct?

Title: Re: Concentration and mass
Post by: Hunter2 on February 24, 2015, 01:14:54 AM

The last calculation is wrong. The molar mass off KCl is 74,5 g/mol

Title: Re: Concentration and mass
Post by: orgo814 on March 30, 2015, 09:43:46 PM

So would the answer be (0.0308 g)(1mol/74.5g) = 4.134 x 10^-4 grams? Kind of a low number...

Title: Re: Concentration and mass
Post by: Hunter2 on March 31, 2015, 12:46:04 AM

No, check your units. This is mole.