## Textbook Problem E.23 part d (Calculating amount of moles)

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Christine Nguyen 1I
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Joined: Wed Sep 30, 2020 9:40 pm

### Textbook Problem E.23 part d (Calculating amount of moles)

The question is:
Calculate the amount (in moles) of (a) Cu+2 ions in 3.00 g of CuBr2; (b) SO3 molecules in 7.00 x 10^2 mg of SO3; (c) F- ions in 25.2 kg of UF6; (d) H2O in 2.00 g of Na2CO3.10H2O.

For part d, I'm confused as to what the dot in between Na2CO3 and 10H2O means. In the book, it's placed a little higher and looks like a multiplication "dot" symbol but I don't think that's what it means. Does anyone know how to solve this part because I was able to understand the previous parts.

Thanks!

tamara masri_3D
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Joined: Wed Sep 30, 2020 9:35 pm
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### Re: Textbook Problem E.23 part d (Calculating amount of moles)

Hi again:) So the dot you're referring to in Na2CO3• 10H20 means that you have a hydrated salt. This pretty much says that the water is not chemically bonded to the salt but it's still there and is still necessary in your calculations. For example, when you find the molar mass of the compound (to convert to moles), you have to include the water in that mass.

Christine Nguyen 1I
Posts: 40
Joined: Wed Sep 30, 2020 9:40 pm

### Re: Textbook Problem E.23 part d (Calculating amount of moles)

tamara masri_3D wrote:Hi again:) So the dot you're referring to in Na2CO3• 10H20 means that you have a hydrated salt. This pretty much says that the water is not chemically bonded to the salt but it's still there and is still necessary in your calculations. For example, when you find the molar mass of the compound (to convert to moles), you have to include the water in that mass.

That makes so much sense, thank you so much for your help!! :)

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