1. how many individual atoms are there in each of the following ? (a) 32 moles of sulphur (b) 32g of sulphur (c) 32u of sulphur (S = 32) 2. how many moles are there in each of the following ? (a) 280g of silicon (b) 12.044 x 10^25 atoms of phosphorus (c) 19.0 atoms of fluorine 3. One mole of zinc atoms weigh 65g. calculate the weight of one atom of zinc.

1 mole of sulphur contains = 6.022$\times $10

^{23}atoms

32 moles of sulphur = 6.022$\times $10

^{23}$\times $32 = 192.7$\times $10

^{23}atoms

b) 32 g of sulphur

32 g of sulphur contains = 6.022$\times $10

^{23}atoms

c) 32 u of sulphur

32 u of sulphur contains = 6.022$\times $10

^{23}atoms

2) a) 280 g of silicon

Molar mass of silicon = 28 g

Number of moles (n) = $\frac{\text{Givenmass}}{\text{Molarmass}}$

n = $\frac{280}{28}$ = 10 moles

b) 12.044$\times $10

^{25}atoms of phosphorus

6.022$\times $10

^{23}atoms = 1 mole of phosphorus

12.044$\times {10}^{25}$ atoms = $\frac{1}{6.022\times {10}^{23}}\times 12.044\times {10}^{25}$ = 2$\times $10

^{2}moles

c) 19 atoms of flourine

6.022$\times $10

^{23}atoms = 1 mole of flourine atom

19 atoms of flourine = $\frac{1}{6.022\times {10}^{23}}\times 19$ = 3.15$\times $10

^{-23}moles

3) 1 mole = 6.022 X 10

^{23}atoms

6.022 X 10

^{23}atoms of zinc weigh = 65 g

1 atom of zinc weighs = 65 / 6.022 X 10

^{23}= 10.79 X 10

^{23}g

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