# chemistry

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calculate number of atoms in 4.67 mol of Ca(NO3)2
I got:
2.81 X 10^24 C atoms or should it be 28.11 x 10^23 C atoms?
5.62 X 10^24 N atoms or should it be 9.34 x 10^23 N atoms?
1.69 x 10^25 O atoms....but are you allowed to do ^25 or should it be 168.7 X 10^23 O atoms I'm confused about exponents again.
also, do I need to worry about rounding to the correct number of signifcant digits when doing these questions?

• chemistry -

Always round to the correct number of significant digits.

Proper scientific notation is X.SY*10^qr

2.84*10^24
5.62*10^24
1.69*10^25 are all correct.

• chemistry - BOB PURSLEY -

would it have still been right if I didn't change the exponent, and say for C atoms, left it at 28.11 X 10^23?

• chemistry -

It is not in correct scientific notation, The number is of course, correct.

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