1 2 3 4 5 6 7 8 9 10 11 12
< Previous Day Thursday Jan 21, 2021 Next Day >
Grid
List

Today
Week
2-Week
3-Week
4-Week
Month

Search
Login
• Formula of a Hydrate [details]
CHEMISTRY
January 21, 2021

Topic: Formula of a Hydrate



Demonstrate: dessicant, and hygroscopic nature of hydrates.

Data for hydrate

Vocabulary
Anhydrous salt: an ionic compound (i.e., a salt) that attracts water molecules and forms loose chemical bonds with them.
    "anhydrous" = "without water"
        symbolized by MN (M = metal, N = nonmetal)
Hydrate: an anhydrous salt with water attached
    symbolized by MN ?H2O (where ? is a "nice" number)
        examples: Na2CO3 . 10 H2O
    CuSO4 . 5 H2O

    USES: in a dessicator, to keep chemicals dry
    as dessicants (in vitamin bottles, leather goods, electronics equipment)

Dessicant
Hygroscopic absorbs moisture from its environment

    some restaurants put dry rice in the salt shaker to absorb moisture so that the salt doesn't "cake" (stick together).

Unsaturated "not full" [(a snack) or (dry sponge)]
Saturated "full" [(a meal) or (soaking wet sponge)]
Supersaturated ""ate too much" [Thanksgiving dinner...unstable and may "lose" material at any time]

Finding the Formula of a Hydrate from Experimental Data
     1. Find the # of g of MN and # of g of H2O
     2. Convert g --> mol
     3. Divide each "# of mol" by the SMALLEST "#of mol"
     4. Use the ratio to find the hydrate's formula

Example 1: Given
    mass of sample before heating = 4.38 g (hydrate = MN + H2O)
    mass of sample after heating = 1.93 g (anhydrous salt = MN)
    molar mass of anhydrous salt = 85 g

ANSWER MN .6H2O

Another example of a hydrate

HW: Read lab & complete Pre-laboratory:  Formula of a Hydrate  PowerPoint  pdf 


            Our aspirations are our possibilities.
                - Dr. Samuel Johnson, 1709 1784

 

• AP CHEM [details]
AP Chem
January 21, 2021

TEST: Chemical Equilibrium & Weak Acids
Powered by CalendarScript