Calculate the following quantity: The total numbers of ions in 38.57g CaBr2 When you have the answer, determine its log (base 10) and enter that value in three decimal.

This is what I got but I'm off according to the answer key.

CaBr2 = 199.88g/mol

38.57g CaBr2 / 199.88g CaBr2 * 6.022x10^23 =1.162x10^23

log(1.162x10^23) = 23.065

The answer key says its 23.543 +/- 5%

Can someone see what my mistake was? Calculator set wrong maybe?

Question

Calculate the following quantity: The total numbers of ions in 38.57g CaBr2 When you have the answer, determine its log (base 10) and enter that value in three decimal.

This is what I got but I'm off according to the answer key.

CaBr2 = 199.88g/mol

38.57g CaBr2 / 199.88g CaBr2 * 6.022x10^23 =1.162x10^23

log(1.162x10^23) = 23.065 

The answer key says its 23.543 +/- 5%

Can someone see what my mistake was? Calculator set wrong maybe?

aaronq · Answer

in this step: 38.57g CaBr2 / 199.88g CaBr2  * 6.022x10^23

you need to multiple by 3 because CaBr2 ionizes into 3 ions.

like: $CaBr_2\rightarrow Ca^{2+} + 2Br^-$

anonymous · Answer

Oh! That makes perfect sense! Thank you so much! I really appreciate the help!

aaronq · Answer

no problem, glad i could help !