Question

A chemist adds of a M barium acetate solution to a reaction flask. Calculate the mass in grams of barium acetate the chemist has added to the flask. Round your answer to significant digits.

Answer 1

Complete Question:

A chemist adds 55.0 mL of a 1.1M barium acetate (Ba(C2H3O2)2) solution to a reaction flask. Calculate the mass in grams of barium acetate the chemist has added to the flask. Round your answer to 2 significant digits.

Answer:

15 g

Explanation:

The concentration of the barium acetate is given in mol/L (M), thus, the number of moles (n) of it is the concentrantion multiplied by the volume (55.0 mL = 0.055 L):

n = 1.1 * 0.055

n = 0.0605 mol

The molar mass of the substance can be calculated by the sum of the molar mass of each element, which can be found at the periodic table. Thus:

Ba = 137.33 g/mol

C = 12.00 g/mol

H = 1.00 g/mol

O = 16.00 g/mol

Ba(C2H3O2)2 = 137.33 + 4*12 + 6*1 + 4*16 = 255.33 g/mol

The molar mass is the mass divided by the number of moles, thus the mass (m) is the molar mass multiplied by the number of moles.

m = 255.33 * 0.0605

m = 15.45 g

Rounded by 2 significant digits, m = 15 g.