Nomenclature, molecular mass, moles help (attempted problems already)

[Edin_Dzeko]

Alright, below are screen captures of some work that I'm tackling. They show my attempts and answers at the problems. I would like to know whether I'm correct or wrong and how to correct the mistakes. The one I need most help with is, the one where you're given density and asked to find molecules. Help will be greatly appreciated. Thanks in advance.

http://img811.imageshack.us/img811/6668/molecules.jpg

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http://img18.imageshack.us/img18/9577/nomenclature1.jpg

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http://img845.imageshack.us/img845/9237/nomenclature2.jpg

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http://img27.imageshack.us/img27/3218/mm1nl.jpg

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[SteamKing]

How many grams of water are in one mole? (Hint: review the definition of a mole)

 

[Edin_Dzeko]

How many grams of water are in one mole? (Hint: review the definition of a mole)

would I have to calculate it as so:

H: 2x(1.008)
O: 1x(16.00)
--------------
H₂O:18.016 mol H₂0 ? and use that instead in the conversion factor?

What about my other problems. Are they okay?

 

[SteamKing]

You still are not understanding the concept of what a mole of a substance is.

 

[DeeNos]

Hello,

From looking at your work, it seems like you have a good understanding of nomenclature, molecular mass, and moles. Your answers for the first two problems in the nomenclature screenshot are correct. For the third problem, the correct name for the compound is potassium nitrate (KNO3).

In terms of the molecular mass problem, your answer of 180 g/mol is correct. To find the number of moles, you need to divide the given mass (0.1 g) by the molecular mass (180 g/mol). This gives you 0.00056 moles.

For the last problem, where you are given density and asked to find the number of molecules, you need to use the formula: density = mass/volume. Rearranging this equation, you get mass = density x volume. Plugging in the given values, you get 1.5 g = 1.33 g/cm3 x volume. Solving for volume, you get 1.13 cm3.

To find the number of molecules, you need to convert the given density into moles. To do this, you need to use the formula: moles = mass/molecular mass. Rearranging this equation, you get molecular mass = mass/moles. Plugging in the given values, you get molecular mass = 1.5 g/1.33 g/cm3 = 1.13 g/cm3.

Using the molecular mass you calculated earlier (180 g/mol), you can now find the number of moles by dividing the given mass (1.5 g) by the molecular mass (180 g/mol). This gives you 0.0083 moles. Finally, to find the number of molecules, you need to use Avogadro's number (6.022 x 10^23 molecules/mol) and multiply it by the number of moles. This gives you 4.99 x 10^21 molecules.

I hope this helps and clarifies any mistakes you may have made. Keep up the good work!