Homework Help

A student is instructed to make 1 L of a 2.0 M solution of CaCl2 using dry salt. How...

user profile pic

ljm3515 | Student, College Freshman | (Level 1) Valedictorian

Posted November 1, 2012 at 11:53 PM via web

dislike 1 like

A student is instructed to make 1 L of a 2.0 M solution of CaCl2 using dry salt. How should he do this?

1 Answer | Add Yours

user profile pic

jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted November 2, 2012 at 2:40 AM (Answer #1)

dislike 1 like

So in the final sample what we need is 2 moles of `CaCl_2` dissolved in water . Since e have dry salt we need to get a mass of `CaCl_2 ` that refers to 2moles of `CaCl_2` .

Molic mass of `CaCl_2` = 110.98 g/mol


Mass required for 2 moles = 110.98g/mol*2mol = 221.96g

 

`M = dm^(-3) = L `

So what we need is to weigh 221.96g of `CaCl_2` from a precise balance and dissolve them well in a 1L water sample. Once all the `CaCl_2` dissolved in water you will get the 2.0 M `CaCl_2` solution.

 

Assumption;

In the dry sample `CaCl_2` is 100% pure without impurities.

Sources:

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes