Chemistry (and Honors) 9-4-18 Using Density

CHEMISTRY – Hey guys, here’s a pic of some “high density” koi that I saw in Hawaii (at the Dole Pineapple Plantation, of all places!). Great review on density problems today, and more! Remember, in chemistry we use math as a tool, therefore we might work problems a little differently in chemistry than you do in your math class.

When working these problems, don’t forget to follow the problem solving steps we discussed today:

  • Analyze – write down what you’re given and what you’re looking for
  • Plan – write a formula where you isolate the unknown on one side by itself
  • Compute – plug in your data, numbers and units; then cancel the units, and if they cancel correctly, go on to the calculator. Be sure and give your answer what the correct units.
  • Evaluate – does your answer make sense, have you used the correct units, do you have the correct sig figs?

Need more practice? Help session TOMORROW morning, 7:30ish A.M.

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62 thoughts on “Chemistry (and Honors) 9-4-18 Using Density

  1. Black Block Density:

    l = 4.60 cm
    w = 9.60 cm
    h = 2.50 cm

    V = l x w x h
    V = (4.60 cm)(9.60 cm)(2.50 cm)
    V = 110.4 cm^3

    m = 110.415 g

    D = m / V
    D = 110.415 g / 110.4 cm^3
    D = 1.00 g / cm^3

  2. Black Block Density:

    l=12.72 cm
    w=4.19 cm
    h=1.28 cm

    V=l x w x h
    V=(12.72 cm) (4.19 cm) (1.28 cm)
    V= 68.22 cm^3

    m= 65.859 g

    D= m/V
    D= 65.859 g / 68.22 cm^3
    D=0.965 g/ cm^3

  3. Paper White Block Density:

    L: 8.20 cm
    W: 1.30 cm
    H: 8.70 cm

    v= l x w x h
    v= (8.20 cm)(1.30 cm)(8.70 cm)
    v= 92.742 cm^3

    m= 42.199 g

    D= m/v
    D= 42.199g/ 92.742 cm^3
    D= 0.455 g/cm^3

    = Alpha

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