1.) How many carbon atoms are contained in a 1.500 carat diamond (carbon) if 1 caret =200.0 mg?

Question

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I don't know if I'm doing this right but I tried. Can someone help?

1.500 carat diamond (C) *(200.0 mg/1 caret) ...

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3.) Magnesium has a sensity of 1.74 g/cm^3. How many atoms of magnesium are contained in a volume of 12.0 cm^3?

Because they give the Density & Volume, I found the mass but i'm not sure how to do the rest.
DV=M; (1.74g/cm^3)(12.0cm^3)=20.88g

Answer 1

1. What yu have gives you mg C. Convert that to grams, then to mols, then to atoms remembering there are 6.02E23 atoms in 1 mole.

2. You have mass Mg. Convert to mols, then to atoms.

Answer 2

Here are my answers after I figured it out. Are these correct though?

1.) 1.50 *10^25 atoms C
2.) 5.173 *10^23 atoms Mg

Answer 3

1 is no. Post your work and I'll find the error. Follow my steps. I suspect you didn't convert mg to grams.

2. ok

Answer 4

1.) Here is what I did.

1.500 carat diamond (C) * (200.0 mg C/1 caret diamond C) * (1 g C/ 1,000 mg C) *( 1 mol C / 12.011 g C) * (6.022*10^23 atoms C/ 1 mol C)

Sorry its confusing when you type it