lab report

Name: _____________________________

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Exp. 4. Report Form: Determination of the (Empirical) Formula of a Hydrate

A. Questions and Observations Associated with the Procedure

1. What is the color of the crystals of CuxCly  zH2O that are added to the crucible? __________________

2. Why is the heating done gently, rather than intensely (as last week)?

3. Describe what you saw during the heating as far as color goes. Does the solid all change at the same time and in the

same physical place in the sample or does it start in one area and then progress to other area(s)?

4. (i) Describe the two major changes, visually, that occurred in the beaker over the course of the first 5-10 minutes after

the wire is dropped into the solution. One of these is associated with the solution, the other with the wire.

NOTE: I do not mean the formation of bubbles here—those are not actually associated with the reaction of interest (ask, if you are interested

about the bubbles.).

(ii) What are you to assume is occurring at the molecular level to explain each of these changes?

(iii) Describe the other change (not “visual”) that occurred during the reaction, which you should have felt with your

hand during the procedure. What do you think this indicates about the reaction(s) that are occurring in the beaker

during this time?

5. After the copper is transferred to the filter paper in the Buchner funnel and washed well with water, one liquid

(ethanol, 95%) is added, allowed to sit for a bit, and then pushed through under low pressure via vacuum filtration.

Then another liquid (acetone) is used similarly, and air is drawn through via vacuum for 8 or so minutes. What is the

purpose of these steps?

Report Form, Determination of the (Empirical) Formula of a Hydrate

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B. Raw Data That Are Measurements (not observations)

Mass of crucible (without cover) __________________

Mass of (uncovered) crucible with solid hydrate __________________

Mass of (uncovered) crucible and residue, Reading 1

(after cooling for a total of _____ min; still warm? Y or N?) __________________

Mass of (uncovered) crucible and residue, Reading 2

(after cooling for a total of _____ min; still warm? Y or N?) __________________

Mass of (uncovered) crucible and residue, Reading 3 (ONLY IF NEEDED)

(after cooling for a total of _____ min; still warm? Y or N?) __________________

Mass of filter paper __________________

Mass of watch glass __________________

(final) Mass of watch glass + filter paper + copper (once fully dry) __________________

Calculated Quantities and Results (SHOW ALL SETUPS):

Mass of solid hydrate sample __________________

Mass of residue (anhydrous compound) __________________

Mass of H2O in hydrate sample (assume all mass lost on heating is due to water loss) __________________

Mass of copper in hydrate sample __________________

Mass of chlorine in hydrate sample (assume any mass in the sample unaccounted for is due to Cl) __________________

Moles of H2O in hydrate sample __________________

Moles of copper in hydrate sample __________________

Moles of chlorine in hydrate sample __________________

Mole ratio, Cl (atoms) to Cu (atoms) in hydrate sample _________: 1  ____: 1

Mole ratio, H2O (molecules) to Cu (atoms) in hydrate sample _________: 1  ____: 1

Formula of the anhydrous compound (dehydrated compound) __________________

Formula of the hydrate (hydrated compound) __________________

(to proper # of SF) (nearest integer)

(to proper # of SF) (nearest integer)

Report Form, Determination of the (Empirical) Formula of a Hydrate

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C. (Optional) Raw Data from Data Set Data Set #:______ Formula of Hydrate (with x, y, z): _________________

Mass of crucible __________________

Mass of crucible and solid hydrate __________________

Mass of crucible and residue (fully cooled) __________________

Mass of filter paper __________________

Mass of watch glass __________________

Mass of watch glass + filter paper + metal (fully dry) __________________

Calculated Quantities and Results (SHOW ALL SETUPS):

Mass of solid hydrate sample __________________

Mass of residue (anhydrous compound) __________________

Mass of H2O in hydrate sample (assume all mass lost on heating is due to water loss) __________________

Mass of _____________ [your metal] in hydrate sample __________________

Mass of _____________ [your anion element Cl or Br] in hydrate sample __________________ (by difference, as above.)

Moles of H2O in hydrate sample __________________

Moles of ______________[your metal] in hydrate sample __________________

Moles of ______________[your anion element] in hydrate sample __________________

Mole ratio, _____ [Cl or Br] (atoms) to _____ [your metal] (atoms) in hydrate sample _________: 1  ____: 1

Mole ratio, H2O (molecules) to _____[your metal] (atoms) in hydrate sample _________: 1  ____: 1

Formula of the anhydrous compound (dehydrated compound) __________________

Formula of the hydrate (hydrated compound) __________________

(to proper # of SF) (nearest integer)

(to proper # of SF) (nearest integer)