Question

Copper(II) bromide is used as a wood preservative. What mass of CuBr2 is needed to prepare 750.0 mL of a 1.25 M solution?

Answer 1

Answer:209.53

Step-by-step explanation:

Molar concentration=moles/Volume. Volume is given as 750mL which can be converted as 0.75l,so moles of CuBr2 is molar concentration ×Volume= 1.25×0.75=0.9375

Mole =mass of CuBr2/molecular Mass of CuBr2.

Molecular Mass of CuBr2 is 63.5+80×2=223.5(mass number of Cu=63.5 and Br=80).

So mass required= 223.5×0.9375=209.53g

Answer 2

238.2 g of CuBr₂ is the mass needed

Step-by-step explanation:

To work with molarity and volume, we can find the mass of solute as this

Molarity . volume (L) = moles → moles . molar mass = mass

1.25 mol/L . 0.750L = moles

0.9375 moles

0.9375 mol . 223.35 g/mol = 238.2 g of salt