How do you solve this?

Question

A chemist adds 350.0mL

 of a 0.233

M calcium bromide CaBr2

 solution to a reaction flask. Calculate the mass in grams of calcium bromide the chemist has added to the flask. Round your answer to 3

 significant digits.

Answer 1

Marco,

first calculate the no. of moles of CaBr_{2 by multiplying the concentration and the volume in L units.}

_{the concentration is 0,233M and the volume is 350.0 mL.}

_{Since the volume is not in L, we must convert from mL to L by dividing by 1000, so 350.0/1000 = 0.3500 L}

Now we can multiply the concentration by the volume in L to get the moles:

0.233 M x 0.3500 L = 0.0816 moles of CaBr₂

_{Finally, convert these moles to mass in grams by using the molar mass calculated from the masses on the periodic table: 1Ca +2 Br = 40.078 + 2(79.9) = 199.878 g}

_{This means that 1 mole of CaBr2 = 199.878 g}

_{So, 0.0816 moles = 0.0816 moles x 199.878 g/1 mol = 16.3 g CaBr2.}