A 20.0 cm3 sample of a 0.400 mol dm−3 aqueous solution of a metal bromide (MBrn) reacts exactly with 160 cm3 of 0.100 mol dm−3 aqueous silver nitrate. What is the formula of the metal bromide? (1 mark)
A 20.0 cm3 sample of a 0.400 mol dm−3 aqueous solution of a metal bromide (MBrn) reacts exactly with 160 cm3 of 0.100 mol dm−3 aqueous silver nitrate. What is the formula of the metal bromide? (1 mark)
A. MBr B. MBr2 C. MBr3 D. MBr4
Silver nitrate is AgNO3 and silver bromide is AgBr.
So therefore the ionic equation should be Ag^+ (aq) + Br^- (aq) --> AgBr (s)
What does this ionic equation tell you about how the moles of Ag^+ and Br^- are related?
Well, since the equation shows the silver and bromide ions react in a 1:1 ratio, that must mean that the moles of bromide ions in the solution must be the same as the number of moles of silver ions.
Try calculating how many moles of AgNO3 were used (this is the same as the number of moles of silver ions, since each AgNO3 contains one Ag^+ ion) and how many moles of MBrn were used.
From this, how might you work out how many bromide ions there are per MBrn?
Really? Is there an easy way to spot how to do it or is it just that?
Yeah, it’s essentially the same process as you would use to find an empirical formula - only understanding why that is the case involves more thought and the method used to find the moles of each constituent element is different to normal.
Yeah, it’s essentially the same process as you would use to find an empirical formula - only understanding why that is the case involves more thought and the method used to find the moles of each constituent element is different to normal.