Metallic Crystal Growth: Growth in gels & Atomic deposition

 

Audience

High School- Chemistry 

Grades 10, 11, 12

Collaborative groups  


Time Frame

Activity 1: Crystal Pudding

Set-up: 1 day

Activity: 1 day

Clean up: 30 min

Activity 2: Avogadro says…

Set-up: 30min

Activity: 1 day

Clean up: 30 min


Objective(s)

After completing the activity, participants will be able to:

1. Calculate the quantity of atoms formed using Avogadro’s law.

2. Analyze the reaction using stecheiometry.

3. Predict the products in single and double displacement reactions.  

4. Predict using potentials if a reaction is spontaneous or not. 

5. Relate the applications that semiconductors have in our daily life.   


Standards Addressed

Next Generation Science Standards:

HS-PS1 Matter and Its Interactions:

A. HS-PS1-2. Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties. 

B. HS-PS1-7. Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction. 

HS-PS2 Motion and Stability: Forces and Interactions:

A. HS-PS2-6. Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.  

Engineering principles: 

HS-ETS1 Engineering Design:

A. HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering. 

Puerto Rico National Standards
NATURALEZA DE LA CIENCIA, TECNOLOGÍA Y SOCIEDAD
NC.Q.2.5 Aplica técnicas de laboratorio apropiadas de acuerdo a la situación.
NC.Q.4.1 Explica cómo se usan las teorías, leyes y principios para describir y  predecir fenómenos naturales como por ejemplo, la estructura atómica y el comportamiento de los gases.
LAS INTERACCIONES:
I.Q.4 Explica las reacciones químicas como el proceso dónde los átomos se reorganizan a escala microscópica. 
I.Q.4.1 Identifica y provee ejemplos de evidencias que indican cuándo ha ocurrido una reacción química tal como: bioluminiscencia, oxidación de metales, fuegos artificiales y otros.
LA CONSERVACIÓN Y EL CAMBIO:
C.Q.1.4 Establece que en una reacción química el tipo y la cantidad de átomos se  conservan aunque cambia la forma en que están combinados.
C.Q.2.3 Describe y compara la estructura cristalina y las propiedades de diferentes tipos de sólidos.


Activity 1 Materials

1. Knox gelatin

2. Petri dish

3. Straw

4. Food coloring (at least 2 colors)

5. 10ml 1M solutions of: Silver nitrate, calcium chloride, sodium carbonate, potassium chloride. 

6. Distilled water

7. Hot plate

8. Spatula

9. Scale

10. Marker


Activity 2 Materials

1. Slide 

2. copper wire (thin)

3. zinc wire (ribbons)

4. paper clips (as iron wire)

5. silver nitrate solution 10ml (1M)

6. Scale

7. 50 ml beaker

8. Kim wipes or paper towel 

9. gloves 

Activity 1 Instructions

Set-up (40 min)

*This can be done by the teacher before, or the students can do it, it’s up to the teacher, students may have fun in the whole process anyway.

 

Instructions to make your gelatin base. 

1. Weigh 2.5 g of Knox gelatin (no color) and add 30 ml of distilled water.

2. Mix until it has the consistency of a paste.

3. Heat gently until the mixture is dissolved. 

4. If foam is formed take it out with a spatula. 

5. Add the mixture to a Petri dish. 

6. Wait at least 15-20 min till it stiffs or leave it overnight.

7. When the gelatin is ready, do holes with a straw like in figure 1. Be careful to not lift the gelatin around the hole, when you extracting the cylindrical parts not needed. 

8. Then with a marker write: 

Figure 1

                              


The Next Part of the Activity (30 min)

Solution Preparation:

1. Prepare 2 solutions of 10ml 1M each one (X) sodium carbonate and (Y) calcium chloride.

2. These solutions could last to the entire group, since your using only 3 drops of each solution in each hole. The preparation of the solutions can be done as a demonstration manner, so everybody could review on the Molarity concept. 

3. You could do other solutions and observe different reactions at the same time. Also you can prepare different concentrations of the same two solutions. 

4. Add 1 drop of different food coloring to differ the solutions. (Don’t do this with the silver nitrate solution. 

5. Add 3 drops of solution (X) to one of the holes and add solution (Y) in the hole near.

6. Cover the Petri dish and wait for the diffusion to occur through gelatin.

The Third Part of the Activity (20-30 min)  

*Observe and draw what you see. Answer the questions in the work sheet 1.

Conclusion (15min)

What did you observe?

Where your predictions true?

Why you think we use the gel to make the reactions happened?

Do you think that is important to use the gel or is irrelevant?

What were your products? 

Assessment

How will you assess your activity? 

Pre-pos test can be administrate to students in order to evaluate if the concepts were reinforced. 

Background**

Students should know these concepts:

Chemical Formulas

Types of reactions

Balance reactions

Molarity

Solutions

Atoms arrangement (crystalline structures)

**Background information of how does the activity relates with strong LAB science, RESEARCH is also important. Teacher may prepare a presentation of how crystalline arrangement is important to create new technologies like chips, semiconductors, thin films or solar cells. 

Activity 2 Instructions

Set-up (15 min)

This activity can be developed using collaborative groups of 4-5 students. Each desk should have a scale, 50ml beaker, 10ml of a 1M silver nitrate solution, zinc, copper, iron (paper clips) wires

The Next Part of the Activity (15 min)

1. Weight each wire and write the mass.

2. In a slide put the wires in a manner that they touch the silver nitrate solution and they don’t touch each other Fig 1.

3. Put the reaction apparatus in the silver nitrate solution and wait 10-30 seg. 

4. Take out the slide and separate the wires let the wires dry for a bit. 

5. Weight them again separately.

6. Answer the questions in worksheet 2 

Figure 1                                                     Figure 2

                              

                                                   

The Third Part of the Activity (20-30 min)  

*Observe …what you see?  Answer the questions in the work sheet 2.

Conclusion (X min)

What did you observe?

Where your predictions true?

Which of the wires produce more atoms, why?

Were your potentials calculations accurate and related to the quantity of atoms?

What were your products? 


Assessment

Pre-pos test can be administrate to students in order to evaluate if the concepts were reinforced. 

Background**

Chemical Formulas

Types of reactions

Balance reactions

Molarity

Solutions

Atoms arrangement (crystalline structures)

Potentials

Reduction and Oxidation

Avogadro’s law

Supplemental Materials

Worksheet 1 “Crystal Pudding” 

Worksheet 2  “Avogadro says…”

References

Brown L. (2004)  Química La ciencia central (México) Novena Edición 

Henisch (1970) Crystal Growth in gels, The Pennsylvania state University Park and London 

Holden A. & Morrison P. (1999) Crystals and Crystal Growing 12 Printing 

Siub S. L., Crystal Growth in gels University of Connecticut, Storrs, CT 006268, Vol 62 Num. 1 Jan 1985pags 81-82 

Panreac (2006) Prácticas de Química, Formación de diferentes cristales metálicos Recuperated June 12, 2013

Bulg J. P. (2007) Crystal growth and characterization of carbonates of Calcium Barium and Strontium in gel media, 34 (108-115)


Authors

Linda I. Vargas Mercado

MRSEC IEG Leadership Team: Ben Taylor, [Prof. Tom Kuech , Gareth Westler MS Materials Science], and Anne Lynn Gillian-Daniel.



Supplemental Materials

Worksheet 1

“Crystal Pudding”

I. Color you pudding according to the pattern that you created. 

II. Color or indicate where the reaction products were observed. 



III. Write the compound that you have in your crystal pudding

             Positions                         A                             B                              C                
                  1      
                  2      
                  3      

IV. Can you mention what were your products? Write combinations of to positions. For example: 

           +                              +            

         A1                                            A2                                                  PREDICT

If you used different compounds, Can you determine the products?   Remember to write the chemical reaction correctly 

Worksheet 2

“Avogadro says…..”

I. Write the two balanced reactions that are taking place in the solution of ___________.  

A. __________    +        __________               _____________  +  __________

B. __________    +        __________               _____________  +  __________

II. According to the numbers of moles can you calculate the numbers of atoms of ________ you deposited? Which is the molar ratio?

Table 1: Is your reaction spontaneous? 

Wire   Solution C   Wire Potentials    Solution Potential    Total Potential cell = cathode -anode 
 A.        
 B.        

Table 2: Avogadro’s Atoms 

 Wire  Mass before reax. (g)  Mass after reax. (g)   Difference in mass (g)   Quantity of deposited atoms 
 A.        
 B.