Activity 3A: The Thickness of a Thin Aluminum Sheet



Activity 3A: The Thickness of a Thin Aluminum Sheet

Prelab Questions

Express numerical answers to the correct number of significant figures.

1. What is the volume of a block that has the dimensions:

L = 8.20 cm, W = 2.25 cm, H = 1.00 cm?

V = L X W X H

V = 18.5 cm3

2. If the density of a substance is 0.525 g/cm3 and the volume of a sample

of this substance is 18.25 cm3, what is the mass of this sample?

M = D X V

M = 0.525 g X 18.25 cm3 = 9.58 g

cm3

3. A piece of paper is known to have an area of 30.2 cm2 and has a volume of

5.2 X 10-3 cm3. What is the thickness of this paper?

Thickness: Volume

Area

T= 5.2 X 10-3 cm3= 1.7 X 10-4 cm

30.2 cm2

Data

Be careful, your measurements should have the correct number of significant figures!!

|Sheet No. |Type |Length (cm) |Width (cm) |Mass (g) |

|1 |Regular |9.85 |15.00 |0.57 |

|2 |Regular |9.85 |15.00 |0.57 |

|3 |Heavy |17.71 |17.90 |2.00 |

|4 |Heavy |15.20 |15.05 |1.00 |

Calculated Results

|Sheet No. |Type |Area (cm2) |Volume (cm3) |Thickness (cm) |

|1 |Regular |‘147’.75 |0.’21’111 |1.4 X 10-3 |

|2 |Regular |‘147’.75 |0.’21’111 |1.4 X 10-3 |

|3 |Heavy |“317.0”09 |0.”740”74 |2.34 X 10-3 |

|4 |Thin?? |“228.7”6 |0.”370”37 |1.62 X 10-3 |

1. a) Compare your results with at least two other teams. How do your answers compare with them?

Team members:

Regular(Ultra Thin) 1.1 to1.5 X 10-3 cm 0.0011 to 0.0015cm

Regular(Thin) 1.6 to 2.0 X 10-3 cm 0.0016 to 0.0020cm

Heavy(Thick) 2.1 to 3.5 X 10-3 cm 0.0021 to 0.0035cm

We may have 3 types of foil (cheap one-Zeller’s, regular, heavy duty)

b) Can you determine how accurate your measurements are? (Why and

explain)

Yes, if we use a micrometer as it is more precise than a ruler

Measurement with a micrometer:

Heavy aluminum: 0.035 mm or 0.0035 cm

Regular thin aluminum: 0.020 mm or 0.0020 cm

Ultra thin aluminum: 0.0011 mm

2. How precise are your answers? Recall the definition of precision.

Precision deals with number of sig fig.

Our measurements are precise since they have as many sig figs as the micrometer.

3. If you had used a very crude balance that allowed only one significant figure, how would this have affected your results for:

(provide a new number of sig fig)

Area? No effect, ruler measures with 2 decimal places

Volume?

Yes, since the mass is less precise, the volume would be less precise, 1 sf .

Thickness?

Yes, since the volume would be 1 sf, the thickness would also be 1 sf.

Synthesis

1. Could we used this method of measurement to determine the thickness of

an oil spill? What additional information would be needed?

Yes, if we know the oil density, area (size of spill), and

volume (haul size), of oil spill

2. A very thin layer of gold plating was placed on a metal tray that measured

25.22 cm by 13.22 cm. The gold plating increased the mass of the plate by 0.0512 g. Calculate the thickness of the plating. The density of gold is

19.32 g/cm3. Show all your work and use the correct number of significant figures.

Road Map:

Thickness: Volume

Area

Area: length X width = 25.22 cm X 13.22 cm = 333.4 cm2

4 sf 4 sf = “3.334”084 X 102 cm2

Volume: mass = 0.0512g X cm 3 = 2.65 X 10-3 cm3

density 1 19.32 g = 0.00”265”0104 cm3

Thickness: “2.65”0104 X 10-3 cm3 = 3sf =7.95 X 10-6 cm

“3.334”084 X 102cm2 4sf = 0.000 007 95 cm

3. By mistake, a quart of oil (1.06 quarts = 1 liter =1000 cm3) was dumped

into a swimming pool that measures 25.0 m by 30.0 m. The density of

the oil was 0.750 g/cm3. How thick was the resulting oil slick?

Be careful with significant figures and scientific notation. (Show your work.)

Thickness: Volume

Area

Area: length X width

Volume: quart ( cm3

Length: 30.0 m = ‘3 00’0cm = 3.00 X 103 cm

Width: 25.0 m = ‘2 5’00 cm = 2.50 X 103 cm

Area= (2.50 X 103 cm) X (3.00 X 103 cm) = 7.50 X 106 cm2

Volume= 1 qt X 1000 cm3 = 943 cm3

1 1.06 qt

Thickness = 943 cm3 = 1.26 X 10-4 cm

7.50 X 106 cm2

4. How might this method of finding thickness be used in finding the

size of molecules(thickness)? What information would we need?

Amount(Mass), Size?(Volume), Kind?(Density of molecule)

Conclusion

Using scientific notation and the correct number of significant figures, what is the thickness of the two types of aluminum foil?

Regular Ultra Thin: 1.1 -1.8 X 10-3cm

Regular Thin: 1.9 -2.0 X 10-3cm

Heavy: 2.1- 2.5 X 10-3cm

/32 marks

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download