The chemical formula for hydrogen bromide is HBr. A chemist determined by measurements that 0.045 moles of hydrogen bromide participate in a chemical reaction. Calculate the mass of hydrogen bromide that participates. Round your answer to 2 significant digits

Mass = 3. 6 ( 2 significant digits)

Explanation:

Number of moles = 0.045

Mass = ?

Relationship between number of moles and mass is given as;

Number of moles = Mass / molar mass

Mass = Number of moles * Molar mass

Mass = 0.045 * 80.91g/mol

Mass = 3.641

Mass = 3. 6 ( 2 significant digits)

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation: