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.

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

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

Have we decided when we are turning the lab in yet?

I don’t think we have

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