Question

calculate the number of chloride ions in 9.5 gram of magnesium chloride given the atomic mass of magnesium is 24 and chloride is 35.5

Answer 1

no of moles = given mass / molar mass

molar mass of mgcl2 is mass of mg + mass of 2 cl atom

                                         24 + 2*35.5 =94

given mass =9.5g

so, no of moles =9.5/94=19/188

no of ions = no of moles * avagadro no

                      19/188 * 6.022 *10

Answer 2

hey!

1 mole of mgcl2 = 24+2*35.5

= 24+71

= 95 g

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1 mole of mgcl2 contains 2 moles of Cl

mass of Cl in 1 mole of mgcl2 = 2*35.5= 71 g

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95 g mgcl2 contains 71g of cl

9.5 g mgcl2 contains 71/95*95/10= 7.1 g of Cl

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now,

35.5 g aluminium has ions 6.022*10^23

7.1 g aluminium has ions 6.022*10^23 *7.1/35.5

= 1.244*10^23 ions