Question

Determine the number of bromide ions in solution when 4.23 g of magnesium bromide and 1.21 g of potassium bromide are dissolved in 120mL of water.

Please explain not sure how to even start this problem, thanks!

Answer 1

Convert 4.23 g MgBr2 to moles and multiply that by 2 to obtain moles Br^- from MgBr2. moles = grams/molar mass.

Convert 1.21 g KBr the same way. Add the moles Br^- together to obtain total moles, then remember that 1 mole of Br^- ions will contain 6.022E23 ions.

Answer 2

4.23g MgBr2 Moles= grams/molar mass

4.23/184.113 = 0.023 moles

1.21g KBr Moles= grams/molar mass

1.21/119.002 = 0.033

and than what? I add those two #'s together? 0.033 + 0.023 = 0.033

and I don't know what you mean by 1 mole of Br- ions will contain 6.022e23 ions where did you get that info?

Thanks!