Experiment #1: Hydrates
Purpose: Determine the formula of a hydrate. (Seeing how scientists even come up with a
Hydrate – a salt that is chemically combined with a certain number of water molecules.
Typical formula: MB(xH O)
M = metal ion (such as Cu ) 2
B = counter ion (such as SO )4
x = number of moles of water per mole of salt
Need to determine what x is in hydrates.
Work in pairs.
Don’t remove glasses until out of the room.
Set up a 600mL beaker as a slop jar for collecting chemical waste including water used
to wash down other objects. Empty the full slop jar into waste container under the hood.
I. A. Quantitative analysis
Wash crucible with soap and water (CAPTURE ALL WASHES IN SLOP JAR) [crucible
WILL be dirty]
set up apparatus for heating crucible
tripod with triangle on top
crucible into triangle
plug in hose for Bunsen burner
turn on gas
use sparker to light burner
adjust rich to lean ratio to get BLUE flame
heat crucible for 5 minutes
turn off gas, remove Bunsen burner
cool crucible for 5 minutes
use tongs to pick up crucible into a clean beaker
take notebook and weigh crucible to two decimals
REPEAT UNTIL MASS CHANGES BY 0.05g OR LESS
Use the lowest weight as the actual weight of the crucible
I. B. [DO II WHILE I IS GOING ON]
Place 0.752.5 g hydrate in crucible using spatula
record ID of hydrate
weigh crucible and hydrate to two decimals
heat until dehydration is complete (steam disappears, color may change)
DO NOT OVERHEAT, will only take 13 minutes
cool for 5 minutes weigh to 2 decima