Chem Lab Test: Lab Processes

Day 1 Processes

Overall Goal — Create Copper Oxide to turn into Copper (II) Pentahydrate in Day 2

Steps:

• Add Nitric Acid to Copper

  • Cu (s)  + 4 HNO₃ (aq) → Cu(NO₃)₂  (aq) + 2 H₂O (l) + 2 NO₂ (g)

  • NO₂ gas is released into the air

• In Ice, add NaOH to the solution, forming Copper Hydroxide

  • Cu(NO₃)₂  (aq) + 2 NaOH (aq) → NaNO₃ (aq) + Cu(OH)₂ (s)

• Adding DI water, release the Hydrogen

  • Cu(OH)₂  (s) → CuO (s) + H₂O (l)

Calculations:

• Needed to do the subtraction of the total mass of Weighglass+compound and Weighglass

Day 2 Processes

Overall Goal — Turn the Copper (II) Oxide into your Copper (II) Sulfate

Steps:

• Add H₂O and Sulferic Acid (H₂SO₄) → formation of Copper Sulfate Pentahydrate and additional H₂O

  • CuO (s) + 5 H₂O (l) + H₂SO₄ (aq) → CuSO₄ · 5 H₂O (s) + H₂O (l)

Calculations:

• Theoretical yield of Compound

• Percent Yield (exper)/theo

• Percent Error |Exper-theo|/theo

Day 3 Processes

Overall Goal — Titrate Cu with EDTA in order to determine the experimental percent of copper present in the sample, compared with the theoretical, with NH₃ as a buffer and Murexide as the indicator

Steps:

• Dissolve CuSO₄ • 5H₂O into H₂O

• Add Ammonium Hydroxide till precipitate forms

• Dilute with DI water

• Add Murexide

• Titrate with EDTA, till color changes to violet

• Overall sequence of events

  • Cu(H₂O) → Cu(NH₃) → Cu(Murexide) → Cu(EDTA)+M

• Main Reaction to know

  • CuSO₄ • 5 H₂O + EDTA → CuEDTA + SO₄ + 5 H₂O

Calculations:

• Calculation from EDTA used CuSO₄ • 5H₂O within a titration & chemical reaction

• Divide Mass of CuSO₄ • 5 H₂O by sample mass for percent of Cu

• Percent Error

Day 4 Processes

Overall Goal — Using Gravimetric processes, determine the percentage of sulfate and water in CuSO₄ • 5 H₂O

Steps:

• Mix solution of CuSO₄ • 5 H₂O + HCl and BaCl₂

  • To prompt the mixing of SO₄^-2 and Ba⁺² as a precipitate

• Heat a sample of CuSO₄ • 5 H₂O in a solution, then re-measure the new mass

  • Mass lost will be known as H₂O; thus, measure the mass of H₂O lost from the precipitate

Calculations:

• Experimental and Theoretical Percent of Sulfate and Water in CuSO₄ • 5 H₂O

• Percent Error

Day 5 Processes

Overall Goal — Using spectrophotometric analysis, determine the copper in our CuSO₄ • 5 H₂O

Steps:

• Prepare one stock, then put it into 5 cuvettes, with increasing molarities

  • Greater molarities should result in higher absorbance on the spectrophotometric analysis

• Fill one Cuvette with an unknown amount of CuSO₄ • 5 H₂O

• Undergo spectrophotometric analysis

  • to find an equation for the line of best fit to use to determine the concentration of the unknown

Calculations

• Molarity (from changing volumes too)

• theoretical and experimental percent copper in CuSO₄ • 5 H₂O

• Percent error