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Hydrate Lab - Marc Meinhardt

Hydrate Lab - Meinhardt

Hydrate Lab – Marc Meinhardt

Lesson Plan for 11th Grade Chemistry

Monday - Friday  55 Minute Class Period

Moles/Grams/Balancing Chemical Equations

 


 

 

Principles Investigated: Students will understand what a Hydrate Compound is. They will also know how to name this compound using proper scientific nomenclature. Students will understand that when a hydrate is heated, the water turns into a gas, evaporates, and the remaining compound is the anhydrous salt. Students will also understand the mass after heating will be less than the mass before heating (while water is still attached to the compound)

 

California Content Standards:

a.    Students know how to describe chemical reactions by writing balanced equations.

b.    Students know one mole equals 6.02 x 10 23 particles (atoms or molecules).

c.    Students know how to determine the molar mass of a molecule from its chemical formula and a table of atomic masses and how to convert the mass of a molecular substance to moles, number of particles, or volume of gas at standard temperature and pressure.

d.    Students know how to calculate the masses of reactants and products in a chemical reaction from the mass of one of the reactants or products and the relevant atomic masses.

 

 

Materials:

 

1.     Copper (II) Sulfate (CuSO4) - Hydrate

2.     Bunsen Burner or Hot Plate

3.     Beaker (100-200mL)

4.     Safety Goggles

5.     Scale/Balance

6.     Metal Thongs (to take hot beaker off Bunsen burner or hot plate)

7.     Water

 

 

Procedure:

1.    Put on Safety Goggles

2.     Find Mass of Clean, Dry Beaker

3.     Find Mass of Beaker and Copper Sulfate Hydrate together

4.     Heat Beaker until all color has left the hydrate (left with anhydrous salt)

5.     Once heated, allow to cool and reweight

6.     Add some water to anhydrate salt to hydrate it again

 

 

 

 

Student Prior Knowledge:

The students need to be familiar with moles and mole ratios. Students need to understand how to find molecular mass and calculate grams from the number of moles of a specific compound. Students need to understand nomenclature (how to name chemical compounds) as well as understand what the numbers in a chemical formula represent.

 

 

Explanation:  

 

This lab is very good for the students to understand the concept of a hydrate and what happens to the hydrate when heated. This gives them an insight to a “physical change” rather than a “chemical change”. It is cool to have the students do this lab, because they are creating a reversible reaction which is fun for them to see. They also enjoy seeing the change of the hydrate from blue to white back to blue. Also, the calculation section helps them understand the concepts of moles, mole ratios, empirical formulas, and percent errors.

 

Question and Answer:

1.  What is the mass of the anhydrous salt?

      Answer: Beaker + Anhydrous Salt - Beaker

 

2.  How many moles of the anhydrous salt did you obtain?

Answer: Beaker + Anhydrous Salt - Beaker

 

3. What mass of the water was driven off during your experiment?

 

Answer: Beaker + Hydrate – Beaker + Anhydrous

 

4.How many moles of Water?

 

5.Ratio of moles of water to moles of salt?

 

6.Empirical formula for the hydrate that was determined through your experiment?

 

7.Real formula is CuSO4 * 5H20 – What is the moles of H20 if you have 1.8 moles of CuSO4?

 

8.Calculate actual percent of water in the hydrate listed in #7

 

9.If you stopped experiment before all water was driven off, how would this affect empirical formula?

 

10.Procedure performed to make sure all water was evaporated?

 

11.How would that affect your percent calculation?

 

12. Explain what happens to anhydrous salt when you add water back into it. Why?

 

13. Write the name, formula, and molar mass of your hydrate.

 

14. Two practical purposes of anhydrous salts in everyday life

 

Applications to Everyday Life:

 

Salts are used to preserve food (table salt), and certain anhydrous salts are used in detergents. When you add water to these salts, they become blue and hydrated. Whenever water is removed from something, the remaining is the anhydrous salt, and this is done also in dried food which allows you to preserve food for a long time.

 

References / Links:

 

www.calabasashigh.net – Dr. Bennett

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