## Homework Problem E. 29

Lilyana Villa 1J
Posts: 50
Joined: Sat Aug 17, 2019 12:15 am

### Homework Problem E. 29

Q. A chemist measured out 8.61 g of copper (II) chloride tetrahydrate, CuCl2*4H2O. (a) How many moles of CuCl2*4H2O were measured out? b) How many moles of Cl- (the negative sign should be at the top) ions are present in the sample?
I don't understand how you're supposed to do part B, can someone help me?

SGonzales_3L
Posts: 55
Joined: Thu Jul 11, 2019 12:17 am

### Re: Homework Problem E. 29

For part (b), you are asked to find the number of Cl- ions present in however many moles you calculated in part (a). Given the molecular formula: CuCl2 * 4H2O, you know that in one molecule, there are 2 chlorine ions. This means that the mole ratio is 2 mol Cl-: 1 mol CuCl2 * 4H2O. You can then use this mole ratio to convert between moles of CuCl2 * 4H2O and moles of Cl-.

Ashley R 1A
Posts: 41
Joined: Sat Aug 24, 2019 12:16 am

### Re: Homework Problem E. 29

for this problem, the question asks specifically how many moles of Cl- ions you have, and because of part a), you already have the moles of the entire molecule. you essentially use dimensional analysis to solve for the number of Cl- ions, so you would multiply the number of CuCl2*4H2O moles (which was .0427) by 2 mol Cl-/1 mole CuCl2*4H2O

Camille 4I
Posts: 57
Joined: Sat Aug 24, 2019 12:18 am

### Re: Homework Problem E. 29

How would you use dimensional analysis to determine moles of Cl- ions from 8.61 grams of copper (II) chloride tetrahydrate? I understand how to convert the grams to moles, but I am stuck as how to proceed.

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