Chemistry

Question

An empty 25.00 mL volumetric flask has a mass of 20.550 g. When it is partially filled with metal pellets, the mass is 130.278 g. The flask is then filled to the mark with methanol (density = 0.7918 g/mL), and the total mass of the flask, metal, and methanol is 142.419 g. Calculate the density of the metal pellets

2 Answer

  • Density is a value for mass, such as kg, divided by a value for volume, such as m^3. Density is a physical property of a substance that represents the mass of that substance per unit volume. We calculate as follows:

    Density = (130.278 - 20.550) / (142.419 - 130.278)/0.7918 = 7.16 g/mL
  • Answer:

    11.347 g/mL is the density of the metal pellets.

    Explanation:

    The total mass of the flask, metal, and methanol  = M = 142.412 g

    Mass of flask = 25.00 mL

    Mass of flask and metal pellets = 130.278 g

    mass of flask + mass of pellets = 130.270 g

    M = mass of flask + mass of pellets + mass of methanol

    142.412 g = 130.270 g + mass of methanol

    Mass of methanol = 12.142 g

    Volume of methanol = v

    Density of the methanol = 0.7918 g/mL

    [tex]v=\frac{ 12.142 g}{ 0.7918 g/mL}=15.33 mL[/tex]

    Volume of the flask = V = 25 mL

    Volume of the pellets = V'

    V = V' + v

    V'= V - v = 25 mL - 15.33 mL = 9.67 mL

    Density of the metal pellets = d

    Mass of the metal pellets = m

    Mass of flask and metal pellets = 130.278 g

    20.55 g + m = 130.278 g

    m = 109.728 g

    [tex]d=\frac{m}{V'}=\frac{ 109.728 g}{9.67 mL}=11.347 g/mL[/tex]

    11.347 g/mL is the density of the metal pellets.

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