“If the Shoe Fits” Hydrate Lab - Mr. Carstens...
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“If the Shoe Fits” Hydrate Lab You have probably noticed that some consumer goods, like shoes, contain a small packet labeled “SILICA GEL: DO NOT EAT”. What is that packet for anyway? As you know, many fragile goods can be easily damaged by moisture. The silica gel in each packet is used to soak up water from the atmosphere. This minimizes moisture that causes damage during shipping. Many ionic compounds can be used to soak up water. Before they absorb water, they ’re referred to as anhydrous or “without water.” After they have soaked up the maximum amount of water from the atmosphere, they are called hydrates. A hydrate is a compound with water molecules stuck to it. The chemical formula looks like: BaCl 2 2H 2 O. In this example, for every 1 mole of compound, 2 moles of water are attached. The dot in the formula is used to show that water is loosely attached (not bonded) to the crystals of the compound. If you heat hydrates to very high temperatures, they “dehydrate,” meaning that the water is lost in the form of water vapor. Once all of the water is lost, these compounds are again referred to as “anhydrous.” Consider the following situation: You and your lab partner just designed the most wicked shoe EVER. The shoe is in its final stages of production and will need to be shipped around the world shortly. There is just one problem – you need to ensure that your shoe arrives perfectly dry and not warped or moldy. Ship your product dry and you could earn millions; ship it moldy and your shoe designing career will be over. Remembering what you learned in your chemistry class, you decide to include a small hydrate packet in the packaging. In this lab you and your lab partner will determine which hydrate, copper (II) sulfate or magnesium sulfate will work best in your packaging by determining their percent composition of water and water of hydration. Who knew that Chemistry could help make you millions?!? CuSO 4 X H 2 O (blue crystal) + heat CuSO 4 (white powder) + X H 2 O (steam) MgSO 4 X H 2 O (clear crystal) + heat MgSO 4 (white powder) + X H 2 O (steam) Safety & Materials (Materials: You must read the lab and include all the materials that are needed) 1. Do not ingest chemicals or inhale any fumes. Wear goggles. 2. Always use crucible tongs to handle the hot crucible. Procedure (Split the page) 1. Set up the lab equipment as illustrated to the right. Include a drawing in your observations of your setup. 2. Clean, dry and heat empty crucible for 3-5 min. before massing. Mass empty crucible. 3. Add about 5 grams of hydrate and mass crucible, lid and hydrate. 4. Heat for 10 min. with lid cracked to allow the water exit – do not burn compound! 5. Let cool by placing on base of ring stand. Take mass of crucible, lid and anhydrous compound. 6. Heat again for 5 min., cool, and mass again. Repeat until the mass is consistent. Clay triangle Bunsen burner Ring & Ring stand
Transcript of “If the Shoe Fits” Hydrate Lab - Mr. Carstens...
“If the Shoe Fits” Hydrate Lab You have probably noticed that some consumer goods, like shoes, contain a small packet labeled “SILICA GEL: DO NOT EAT”. What is that packet for anyway? As you know, many fragile goods can be easily damaged by moisture. The silica gel in each packet is used to soak up water from the atmosphere. This minimizes moisture that causes damage during shipping. Many ionic compounds can be used to soak up water. Before they absorb water, they’re referred to as anhydrous or “without water.” After they have soaked up the maximum
amount of water from the atmosphere, they are called hydrates. A hydrate is a compound with water
molecules stuck to it. The chemical formula looks like: BaCl2 2H2O. In this example, for every 1 mole of compound, 2 moles of water are attached. The dot in the formula is used to show that water is loosely attached (not bonded) to the crystals of the compound. If you heat hydrates to very high temperatures, they “dehydrate,” meaning that the water is lost in the form of water vapor. Once all of the water is lost, these compounds are again referred to as “anhydrous.”
Consider the following situation: You and your lab partner just designed the most wicked shoe EVER. The shoe is in its final stages of production and will need to be shipped around the world shortly. There is just one problem – you need to ensure that your shoe arrives perfectly dry and not warped or moldy. Ship your product dry and you could earn millions; ship it moldy and your shoe designing career will be over. Remembering what you learned in your chemistry class, you decide to include a small hydrate packet in the packaging. In this lab you and your lab partner will determine which hydrate, copper (II) sulfate or magnesium sulfate will work best in your packaging by determining their percent composition of water and water of hydration. Who knew that Chemistry could help make you millions?!?
CuSO4 X H2O (blue crystal) + heat CuSO4 (white powder) + X H2O (steam)
MgSO4 X H2O (clear crystal) + heat MgSO4 (white powder) + X H2O (steam)
Safety & Materials (Materials: You must read the lab and include all the materials that are needed)
1. Do not ingest chemicals or inhale any fumes. Wear goggles. 2. Always use crucible tongs to handle the hot crucible.
Procedure (Split the page)
1. Set up the lab equipment as illustrated to the right. Include a drawing in your observations of your setup.
2. Clean, dry and heat empty crucible for 3-5 min. before massing. Mass empty crucible.
3. Add about 5 grams of hydrate and mass crucible, lid and hydrate.
4. Heat for 10 min. with lid cracked to allow the water exit – do not burn compound!
5. Let cool by placing on base of ring stand. Take mass of crucible, lid and anhydrous compound.
6. Heat again for 5 min., cool, and mass again. Repeat until the mass is consistent.
Clay triangle
Bunsen burner
Ring & Ring
stand
Pre- Lab Questions Please put BEFORE PROCEDURE – it is placed here to save paper space.
Washing soda is used to remove stubborn stains from clothes. Washing soda is a hydrate of sodium
carbonate. Its formula is Na2CO3 X H2O. What is X (the number of H2O)?
Sample Data Table
Mass of Crucible and Cover (g) 20.230 g
Mass of Crucible, Cover, and Sodium Carbonate Hydrate, Na2CO3 X H2O (g) 22.714 g
Mass of Crucible, Cover and Sodium Carbonate, Na2CO3 (g) 21.236 g
Empirical Formula Calculation Table: For each calculation you must show all work and units.
Compound Mass of
compound in lab Moles of
compound in lab Simplest ratio
(divide by smallest)
Find X in
Na2CO3 X H2O
Na2CO3
H2O
Percent Water Calculation Table: For each calculation you must show all work and units.
Mass Experimental
% composition of water
Actual
% composition of water % Error
Mass of water in lab 54.4 %
Mass of hydrate in lab
Post-Lab Questions Please put at the END of your lab report – it is placed here to save paper space.
1. Which compound will you select to help keep your shoes in ideal condition during shipping? Why?
2. Look at the percent error for this lab. Comment about your degree of accuracy in this lab. What contributed to the percent error you received?
3. Consider the following sources of error. Determine if they would make your value of X in your hydrate to come out too <H>igh, too <L>ow, or <N>o Effect...
____ the Bunsen burner had left black soot on the bottom of the crucible
____ the hydrate wasn't completely anhydrous (did not lose all its water) after heating
____ some of the salt splattered out during heating while you weren't watching
____ your crucible weighed more than everyone else's
____ you heated your hydrate too strongly. It burned and some sulfate (SO4) escaped as SO2 gas
Data and Calculations
Data Tables
Mass of Crucible and Cover (g)
Mass of Crucible, Cover, and Magnesium Sulfate Hydrate, MgSO4 X H2O (g)
Mass of Crucible, Cover and Magnesium Sulfate, MgSO4 (g)
Mass of Crucible and Cover (g)
Mass of Crucible, Cover, and Copper (II) Sulfate Hydrate, CuSO4 X H2O (g)
Mass of Crucible, Cover and Copper (II) Sulfate, CuSO4 (g)
Empirical Formula Calculation Tables: For each calculation you must show all work and units.
Compound Mass of
compound in lab Moles of
compound in lab Simplest ratio
(divide by smallest) Find X in
MgSO4 X H2O
MgSO4
H2O
Compound Mass of
compound in lab Moles of
compound in lab Simplest ratio
(divide by smallest) Find X in
CuSO4 X H2O
CuSO4
H2O
Percent Water Calculation Tables: For each calculation you must show all work and units.
Mass Experimental
% composition of water
Actual
% composition of water % Error
Mass of water in lab
Ask Instructor
51.2 %
Mass of Mg hydrate in lab
Mass Experimental
% composition of water
Actual
% composition of water % Error
Mass of water in lab
Ask Instructor
36.1 %
Mass of Cu hydrate in lab
