Chemistry (Mass)

Question

1. The daily recommended intake of calcium for adolescent females is approximately 1.10 g. 

 

b)  Each tablet of calcium citrate contains 4.57 X 10-3 mol calcium citrate. How many tablets would an adolescent female have to take to meet her requirements? [2]

 

Answer 1

Hello Zoe,

To figure out how many tablets meet the daily Ca intake requirement, we will need to do stoichiometry. To do this I used the molar mass of 40.078g for Calcium, which I found on the periodic table. I also looked up the chemical formula of calcium citrate (Ca3(C6H5O7)2) in order to see how many moles of Ca there were in 1 mole of calcium citrate.

1.10gCa x (1mol Ca/ 40.078g Ca) x (1mol Ca3(C6H5O7)2 / 3molCa) x (4.57*10^-3)molCa3(C6H5O7)2/ 1 tablet = 2.0019 tablets

or

(4.57*10^-3mol Ca3(C6H5O7)2 x 3mol Ca/ 1molCa3(C6H5O7)2 x 40.078gCa/ 1molCa= 0.549g Ca in 1 tablet

1.10g/0.549g=2.0019

Therefore, in order to meet the daily requirement, a female would need to take 3 tablets; if she only took 2, then she would be short 0.0019 grams of Ca.

I hope this helps!

Best,

Rianna