7/27/2019 Chemistry - Experimental Design

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2013 S1 Science Experimental Design Miss Raja

Here is a summary of terms you must know when approaching experimental design. Make a mind mapin the space below to summarise the meanings of the terms.

Hypothesis Materials Data tables

Aim Methods Variables Fair Tests

Conclusion Experimental Setup

u

o

n

Calcul

Measure the

riginal gauge

ength (Lo) ofhe material

round the

oint ofntended

acture. This

alue is

ommonly 2n. or 50 mm.

7/27/2019 Chemistry - Experimental Design

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2013 S1 Science Experimental Design Miss Raja

Design an experiment to investigate the following.

(A) Find out the percentage purity of a gold necklace using density. You will find the following data

about the density of the gold purities following useful.

14K 12.9 to 14.6 g/ml

18K yellow 15.2 to 15.9 g/ml

18K white 14.7 to 16.9 g/ml

22K 17.7 to 17.8 g/ml

(B)Find out which of the following materials is most ductile.

Plastic Silver

Glass

Gold

Copper

You may find the following steps in an e-how article to measuring ductility useful. The full article canbe found at http://www.ehow.com/how_5417121_calculate-ductility.html

1) Measure the original gauge length (Lo) of the material around the point of intended fracture. This

value is commonly 2 in. or 50 mm.

2) Apply a tensile force to the material slowly until fracture occurs.

3) Fit the broken parts back together and measure the fracture length (Lf) utilizing the same endpoints

on the material as the initially measured gauge length.

4) Calculate the percent elongation utilizing the following equation; % EL=100(Lf-Lo)/Lo.

7/27/2019 Chemistry - Experimental Design

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2013 S1 Science Experimental Design Miss Raja

5) Measure the diameter of the solid cylindrical material to be tested (d).

6) Calculate the original cross-sectional area (Ao) of the rod by using the diameter into the following

equation

7) Apply a tensile force to the material slowly until fracture occurs.

8)Measure the diameter of the cylinder at the point of fracture (df) then calculate the cross-sectional

area at the point of fracture (Af).

9) Calculate the percent reduction in area utilizing the following equation

(C) Order the following in order of increasing hardness after experimental investigation.

Lollipop stick

Pencil (wooden part)

Plastic ruler

Drinks can Rubber Bung

Ceramic plant pot

You may measure the hardness but measuring the depth of a scratch made by a steel blade. You

may also need school glue to help measure said depth.

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2013 S1 Science Experimental Design Miss Raja

(D) Find out which of the following is the most magnetic material.

Silver coin

Copper coin

Magnet

Rubber bung

Wool

Paper clip

You are provided with an electromagnet connected to a voltmeter.

(E) Find out the effect of glue on the strength of paper.