# chemistry

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Mole and Particle practice
How many representative particles (atoms, ions, molecules, etc) are present in each of the following?
1) 4.3 mol of tungsten
2) 2.45 * 10-6 mol nickel (II) selenide (NiSe)
3) 0.923 mol of selenium tetrabromide (SeBr4)
How many moles are equivalent to each of the following?
4) 7.95 * 1024 copper (II) chloride
5) 6.93 * 1023 thallium atoms
6) 1.974 * 1014 sodium chloride formula

• chemistry -

You must type your questions. Cut and paste doesn't work.

• chemistry -

okay
How many representative particles (atoms, ions, molecules, etc) are present in each of the following?
1)4.3 mol of tungsten

2)2.45 * 10-6 mol nickel (II) selenide (NiSe)

3)0.923 mol of selenium tetrabromide (SeBr4)

• chemistry -

There are 6.02 x 10^23 molecules in a mole of molecules or 6.02 x 10^23 atoms in a mole of atoms.
4.3 moles W x (6.02 x 10^23 atoms W/1 mole W) = ?? atoms W. Note how the unit you don't want (moles W in this case) cancel and leaves the unit you want to keep (in this case atoms W).

• chemistry -

I still don't understand can you help me with the first two?

• chemistry -

Think of it this way. There are 40 apples in a bushel. How many apples in 3 bushels?
3 bushels x (40 apples/bushel) = 120 apples. See the unit bushel cancel leaving the unit we want to keep as apples.
4.5 x 10^-6 mol NiSe. There are 6.02 x 10^23 molecules in a mol, so
4.5 x 10^-6 mol NiSe x (6.02 x 10^23 molecules NiSe/mol NiSe) x (2 particles in NiSe/molecule NiSe) = number of particles in 4.5 x 10^-6 moles NiSe.

Again, note mol NiSe in the first term (4.5 x 10^-6 mol NiSe) cancel with mol NiSe in the denominator of the first factor and molecules NiSe in the numerator of the first factor cancel with molecule NiSe in the denominator of the second factor. We wanted to get rid of those units and we did. What's left? The unit we want to keep is particles and that's the only unit that didn't cancel.

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