A sample of gallium bromide, GaBr3, weighing 0.165 g was dissolved in water and treated with silver nitrate, AgNO3, resulting in the precipitation of 0.299 g AgBr. Use these data to compute the %Ga (by mass) GaBr3.

%Ga by mass in sample of is 23.0%

Explanation:

Molar mass of AgBr = 187.77 g/mol

So, 0.299 g of AgBr = moles of AgBr = moles of Br = 0.00159 moles of Br

Br in AgBr comes from

So, there are 0.00159 moles of Br in 0.165 g of

Molar mass of Br = 79.904 g/mol

So, mass of Br in 0.165 g of = = 0.127 g

So, mass of Ga in sample of = (0.165-0.127) g = 0.038 g

So, %Ga by mass in sample of = [(mass of Ga)/(mass of )]%

                                                              = %

                                                              = 23.0%

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.