how many grams of NH3 are needed to provide the same number of molecules as in .5 g of SF6

Answer 1

First, figure out how many molecules there are in 0.5g SF₆

molar mass SF₆ = 146.05 g / mole

moles SF₆ in 0.5 g = 0.5 g x 1 mol / 146.05 g = 3.4x10^-3 moles

Since 1 mole of any substance contains 6.02x10²³ molecules, you will need 3.4x10^-3 mols NH₃ also

molar mass NH₃ = 17 g / mole

3.4x10^-3 mols NH₃ x 17 g / mol = 0.0578 g NH₃ needed = 0.06 g NH₃ needed (1 sig.fig.)

Answer 2

Find how many moles of SF₆ you have by dividing the given mass by its molar mass. This will be the amount of moles of NH₃. Then multiply by its molar mass to get the mass of NH₃.