The effect of the surface area of steel in the size of

ADP crystals (NH4H2PO4)

• De Jesús, H.; Booth, S.; Garcia, J. (2011). El efecto de un metal en la cristalización de un sólido (ADP). Science on Wheels. Mayaguez, P. R.: UPR-Recinto de Mayaguez

• Ram Kripal, Santwana Shukla, Prashant Dwivedi, EPR and optical studies of Cu2+ doped

ammonium dihydrogen phos-phate single crystals, Physica B 407 (2012) 656-663. • P. Rajesh, K. Boopathi, P. Ramasamy, Investigations on the solubility, growth, structural, optical,

mechanical, dielectric and SHG behaviour of ammonium acetate doped ammonium dihydrogen phosphate crystals, J Crystal Growth 318 (2011) 751-756.

• K. Srinivasan, A. Cantoni, G. Bocelli, Compositional dependence of morphology and lattice

parameters during growth of K1-x(NH4)xH2PO4 mixed crystals, Cryst. Res. Technol. 45(7) (2010) 737-746.

• R. Ananda Kumari, Growth and characterization of NLO crystal, Ind. J. Pure & Appl. Phys. 47

(2009) 369-371.

References

Methodology

Problem

Implications

Analysis

Crystallization is an important industrial process because of all the

different materials that can be commercialized in crystal form. The refusal

of the proposed hypothesis leads us to infer that the formation of different

sizes of crystals in these substrates, are dependent not on the surface area

of the material, but on the chemical-electrical reactions stirred up. These

findings have special implications in the electro chemical field,

(according to the reaction that is inferred to have occurred) but it requires

more advanced research in order to be confirmed.

From the point of view of crystallography (the science that studies the

formation and resolution of crystalline structures) the applications are

diverse, given that crystallography is a comprehensive science that

includes diverse disciplines like physics, chemistry, mineralogy, biology,

molecular biology, pharmacology, and is transversal to all other scientific

disciplines. The application in the biology and pharmacology fields is

mainly that one could form crystals from human body molecules. This

could enable a better understanding of the interactions between human

molecules and the molecules that compose specific medicines. Other

applications for this research are found in the popularity and advance in

the computer industries, in the making of crystal semiconductors and

liquid crystal displays which are technological inventions made possible

by the studies in the crystallography field (Example: LCD technology).

This study aims to determine the effect of different substrate diameters on

ADP crystal growth under controlled laboratory conditions. The growth of

ADP crystals is achieved under a supersaturated solution of NH4H2PO4

(ammonium dihydrogen phosphate) followed by a slow decrease in

temperature, which triggers ADP crystals of a certain size and quality.

The development of crystals is initiated in a saturated solution where

nucleation process develops core regions for the production of crystals. A

core is defined as a collection of either atoms, ions or molecule particles

neatly arranged, so that they can serve as a seed for a future crystal. Core

development can be intrinsic or promoted by an exogenous

material(metal). In our research heterogeneous core production is

promoted by the addition of steel rods.

Crystals are materials with great importance on electronic devices since

they act as great electric conducing agents. Specifically, pure ADP crystal

possess isoelectric properties in transduce apparatus, and functions in

optic devices. Therefore, the development of new methodologies for

crystal production are necessary since this has great applications in the

electronic field. For this reason, this study aims to develop a new

methodology for the effective development of pure ADP crystal on a

substrate diameter dependent manner.

Which areas of the steel surface affect the size of the ADP Crystal?

Purpose

The size of the ADP crystals will be bigger as the steel surface area

where they grow is bigger.

Variables

Independent variable

Surface area of steel

Rod Area 3/8 "= 17.6 ± 0.1cm

Rod Area½ "= 25.5 ± 0.1cm

Rod Area 1 "= 52.3 ± 0.1cm

Dependent variable

Size of the ADP crystal.

175 ml HCl 3 molar

Pincers

Safety equipment: gloves, coveralls,

goggles, thermal gloves and extractor.

6 thermometers

Procedures

Initial Data

Determine surface area of steel rods to be used as seeds for dendritic crystal growth of ADP.

Label Styrofoam containers

Remove outer layer of steel rods using 25 mL of (HNO) 3 3.0 molar and 175 mL of hydrochloric acid (HCl) 3.0 molar.

Use 25 mL of the acid for 5 minutes to remove the surface layer of three steel rods.

Wash each rod with plenty of distilled water.

Place the steel inside and in the middle of the Styrofoam containers. Turn on the hot plate and set it to a medium heat.

Weight six 400 mL beakers and identify them as A1, B1, C1, A2, B2, and C2

Use a mortar to pulverize the ADP. Add the ADP into the beaker.

Pour distilled water into the beaker up to 400 mL

Measure temperature and pH of the solution before putting it on the hot plate. Record the temperature and pH obtained.

Place the 400 mL beaker with the solution on the hot plate. Stir

the solution until it reaches a temperature of 70˚C.

Pour the solution into in the Styrofoam container with the steel rod in the center.

Measure the temperature of the solution quickly after pouring it in the container. Cover and seal it with adhesive paper tape.

Record the time and wait 48 hours to observe the results. Measure the pH of the solution after 48 hours. Write down observations.

Repeat the procedures for the remaining steel surfaces.

Control Group The solution without the steel rod.

Experimental Group Solution + Rod 1 " Solution + Rod ½ " Solution + Rod 3/8 "

100%

0%

Colloidal Layer No Colloidal Layer

67%

33%

Graph 4. Qualitative analysis of crystal

shapes (big and thick vs. small and thin)

Big and thick Small and thin

0

25

50

75

100

3/8" (0.95

cm)

1/2"

(1.27cm)

1"

(2.54cm)

Light Yellow 100 100 0

Green 0 0 100

Co

lor

(%)

Graph 1. Color of the solution added to the

steel rods after 48 hrs

0

25

50

75

100

3/8" (0.95 cm) 1/2" (1.27cm) 1" (2.54cm)

Light Yellow 100 100 0

Green 0 0 100

Co

lor

(%)

Steel Initial

Temperature

of Solution

(oC)

Final

Temperature

of Solution

(oC)

Temperature of

Solution inside

styrofoam

container (oC)

Time of

foam

container

sealing

Metal's reaction to

the solution

PH

Round 1

Rod 1’’ 14oC 70oC 69oC 12:52pm

Effervescence on the

extremes

3

Round 1

Rod 1/2’’ 14oC 70oC 68oC 12:58pm

Effervescence on the

extremes

3

Round 1

Rod 3/8’’ 14oC 70oC 50oC 1:00pm

Effervescence on the

crevices.

3

Round 2

Rod 1’’ 14oC 70oC 65oC

3:009pm

Small effervescence on

crevices and much on

extremes.

3

Round 2

Rod 1/2’’ 14oC 70oC 67oC

3:12pm

Small effervescence

around crevices.

4

Round 2

Rod 3/8’’ 14oC 70oC 68oC

3:09pm

Little effervescence.

3

Round 3

Rod 1’’ 14oC 70oC 68oC

3:51pm

Little effervescence. 3

Round 3

Rod 1/2’’ 15oC 70oC 70oC

3:47pm

Much effervescence

3

Round 3

Rod 3/8’’ 16oC 70oC 68oC

3:57pm

No reaction

3

Round 4

Rod 1’’ 15oC 70oC 65oC 4:24pm

Much effervescence on

extremes

3

Round 4

Rod 1/2’’ 18oC 70oC 70oC 4:21 pm

Much effervescence on

extremes and crevices

4

Round 4

Rod 3/8’’ 19oC 70oC 68oC 3:58pm

No reaction

4

Round 5

Rod 1’’ 14oC 70oC 69oC

4:33pm

Much effervescence on

extremes

3

Round 5

Rod 1/2’’ 16oC 70oC 70oC

4:35pm

No reaction 3

Round 5

Rod 3/8’’ 16oC 70oC 70oC

4:31pm

Little effervescence on

extremes

3

Round 6

Rod 1’’ 14oC 70oC 64oC

5:11pm

Little effervescence on

crevices

3

Round 6

Rod 1/2’’ 14oC 70oC 68oC

5:13pm

Little effervescence

3

Round 6

Rod 3/8’’ 17oC 70oC 64oC

5:11pm

Little effervescence on

extremes

3

Hypothesis

Solution Category

Amount of solution: 400 mL

Amount of salt: 188 g

% of concentration: 47%

Distilled water

Controlled variables

Rod Category

Size of the rods: 2inch = 5.08 cm

Surface of the rod: Corrugate

Procedure Category

Cooling system: foam

Final temperature of the solution:70˚C

Cooling time: 48 hours

Location of containers

Beaker: 400 mL

Magnetic stirrer

Heat from warming plate: medium

Results

Graph 2. Color of the crystals formed on

the steel rods

Graph 3. Colloidal layer formation on the

solution added to steel rod (0.95cm,

1.27cm and 2.54cm) after 48 hrs

The temperature of the ADP supersaturated solutions was controlled to

70oC and acid pH between 3 and 4. The ADP supersaturated solutions that

were in contact with the steel of 3/8" and 1/2" of diameter (0.95 and 1.27

cm respectively) became a weak yellow color, while the ADP

supersaturated solutions that became in contact with the steel of 1" (2.54

cm) of diameter, became green after a 48 hour wait. The color of the

obtained crystals varied according to the color of the solution: light

yellow for the crystals whose solutions became light yellow and green for

the crystals formed in the solutions that became green. The pH of the

solutions was taken after the 48 hour wait and these were maintained acid

(pH between 3 and 4). After 48 hours a colloidal layer was obtained in all

the solutions. It was observed that the obtained crystals varied according

to the color of the solution and the diameter of the steel. We obtained

large and thick crystals on the solutions with the steel of 3/8" and ½" of

diameter (0.95 and 1.27 cm respectively), while on the solutions with the

steel of 1" of diameter (2.54 cm) the obtained crystals were small and

thin.

Materials

Salt ADP

Distilled water

6 glasses of 400 ml

Digital scale

Mortar

Heating plate

Glass and magnetic

18 foam container

Colored marker

Tape

Rod 3/8 ", ½"and 1“

25 mL HNO3 3 molar

Conclusion

Our results show that upon contact with the steel, the ADP supersaturated

solution will always emit effervescence, will crystallize with dendritic

morphology and after 48hr (cooling off) the solution will change colors

with colloidal surface. Our research hypothesis established that the greater

the surface area of the steel, the greater the size of the ADP crystal.

According to the compiled data we can conclude that the hypothesis is

rejected because the steel with greater surface area generated the thinnest

and smallest crystals. Furthermore, the medium and smallest surface areas

produced crystals with similar size and thickness. We infer that the surface

area (that is a physical aspect) does not have relation with the size of the

crystals. It is the state of oxidation of the iron that affects the growth of the

dendrites. Our observations after 48 hours indicate a change in the color of

the solutions. In the steel with a diameter of 1" the solutions became

green. While the solutions on the steels of 3/8" and ½" in diameter became

a light yellow color (amber). According to the bibliography the solutions

that contain Ferric (Fe+3) will become green and the solutions that contain

Ferrous (Fe+2) will become light yellow (amber). Future research will be

required to expand on these findings.

Beakers Mass (g)

A₁: 400mL 119.96

B₁: 400mL 161.01

C₁: 400mL 135.90

A₂: 400mL 158.30

B₂: 400mL 156.30

C₂: 400mL 158.87

Mass of Beakers

All pictures taken by students Marangelis Lopez and Janaleen Ayala.