lets start with copper lab report

Alex ZhaoGreg KerrIB Chemistry HLSeptember 7, 2012

Let’s start with copper Lab

BackgroundWhen a chemical changes take place, we may observe one or more of the

following: A substance disappears. A gas is given off A color change takes place A solid is precipitated The temperature changes A new odor appears.

Aim/Objective: Through the various parts of the lab and reactions that take place, we will

observe and identify signs of chemical changes. Starting with approximately 1.5 grams of copper, we strive to recover the same amount of copper after five different reactions. In addition, familiarize oneself with laboratory techniques and identify the science of a chemical reaction

Materials/Equipment: Small pieces of Copper (Cu)

1.5 grams Nitric acid (HNO3) 250 mL Beaker (2~3) Weighing boat Fume hood Watch glass 3M Sodium Hydroxide

(NaOH)

Hot plate/ Bunsen burner Glass Stirring rod Wash bottle (with distilled

water) Measuring Cylinders of

various sizes 3M Sulfuric Acid (H2SO4) Zinc Metal (Zn) 5 grams

Stage One : Reaction between copper, Cu, and a solution of nitric acid, HNO 3, in water.

Procedure: Given vial containing approx. 1.5 grams of copper. Weigh vial

and find mass of copper Tip copper into 250 mL beaker Mix 15mL of nitric acid solution with copper under fume hood

(gas produced is poisonous) Put watch glass on top of beaker (to keep most of the gas in for

observation. Observe. Has a chemical reaction occurred?

Observations:Weighing Boat + Copper: 3.58 grams ± 0.01gWeighing Boat: 2.09 grams ± 0.01g

IB Chemistry HL Lab 1 September 7, 2012

Mass of Copper: 1.49 grams ± 0.01g

Copper: Shiny, solid, malleable, ductile, odorless, brownish color, with traces of oxidation.

Nitric Acid: Liquid, odorless, clear, colorless, transparent.

During Reaction: Gas is given off at the surface of the copper. Possibly

Hydrogen Gas As the reaction progresses, the amount of gas increases. The

solution turns blue-green color. A brown gas is formed, along with an unwelcoming odor Copper turns milky white Temperature rises slightly Copper eventually disappears. Solution left behind is bluish,

liquid, clear, transparent, with odor (though possibly caused by odor of the brownish gas produced)

I believe a chemical reaction has occurred because: A substance disappeared, a gas is given off, a color change took place, the temperature changed, and a new odor appeared. In addition, I believe the copper has dissolved and taken the form of an aqueous compound.

Equation(s): Cu(s) + 4NO3(aq)2NO2(g) + 2H20(l) + Cu(NO3)2(aq)

1 mol of Copper solid + 4 mols of Nitric Acid Solution Yields 2 mols of Nitrogen Dioxide gas+ 2 mols of water + 1 mol of Copper (I) Nitrate.

Stage two: The addition of a solution of 3 molar sodium hydroxide, NaOH, in water

Procedure: Add 40 mL of sodium hydroxide solution to solution in beaker

(yielded after stage 1) while stirring with glass rod Record observations

Observations:Sodium Hydroxide solution: liquid, transparent, colorless,

odorless, uniform, clear.

During reaction: A solid, dark blue precipitate forms Color is darker than original solution, rather milky. Temperature increase.


I believe a chemical reaction has occurred because: a precipitate was formed, a color change took place, and the temperature changed.

The copper should be part of the precipitate (speculation).

Equation: Cu(NO3)2(aq) + 2NaOH(aq) Cu(OH)2(s) + 2NaNO3(aq)

1 mol of Copper (I) Nitrate solution + 2 mol of Sodium Hydroxide solution yields 1 mol of Copper (I) Hydroxide solid and 2 mols of Sodium Nitrate solution.

Stage three: Heating

Procedure: Add 100 mL of distilled water to the beaker Gently heat the beaker and its contents while stirring with

glass rod.

Observations:During reaction:

Color of solution becomes even darker. The precipitate turns into a greenish black particle As heating continues, the greenish black particles turn

completely black, and retain a powdery characteristic. After the particles settle down, the solution above it is

colorless, odorless, liquid, clear, and transparent.

There was a chemical reaction that took place because: a color change took place, and a new substance was formed (milky bluish precipitate becomes blackish, powdery solids).

The copper should now be part of the blackish, powdery solid that settled down.

Equation: Cu(OH)2(s) + Heat CuO(s) + H20(l)

1 mol of Copper (I) Hydroxide solid + Heat yields 1 mol of Cupper (II) Oxide solid + 1 mol of water.

Stage four: Addition of a solution of 3 molar sulfuric acid, H2SO4, in water

Procedure:


Carefully add 50mL of the acid solution to beaker. Stir until no further reaction takes place.

Observe and record

Observations:Sulfuric acid: colorless, clear, transparent, liquid, odorless

During reaction: Solution turns blue green and ends up as bright blue, clear,

transparent, liquid solution. Blackish powder disappears

A chemical reaction took place because: A substance disappears, and a color change took place.

The copper should now be completely dissolved in the homogeneous solution.

Equation: CuO (s)+H2SO4(aq) CuSO4(aq) + H2(l)

1 mol of Copper (I) Oxide + 1 mol of Sulfuric acid solution yields 1 mol of Cupper (II) Sulfate + 1 mol of Hydrogen gas.

Stage Five: addition of zinc Metal, Zn

Procedure: Add 5 g of zinc metal to product in beaker. Place watch glass on

top of beaker Observe any changes Allow reaction to finish Observe and record

Observations:Zinc: Solid, opaque, rather shiny, greyish, hard, and in the form of

small pellets.

During reaction: Bubbles from at the surface of the zinc pellets. The zinc eventually turns blackish brown, and finally

disappears, leaving behind a solid, blackish precipitate and a homogeneous, clear, transparent, and colorless solution.

Equation (s): Zn(s)+H2SO4 (aq)H2(g)+ZnSO4(aq)

Zn(s)+CuSO4(aq)Cu(s)+ZnSO4(aq)

1 mol of Zinc + 1 mol of Sulfuric acid yields 1 mol of hydrogen gas + 1 mol of Zinc Sulfate

1 mol of Zinc + 1 mol of Copper (II) Sulfate + 1 mol of Zinc Sulfate.


Stage 6: RecoveryAfter washing and decanting to obtain the substance from the solution,

and boiling off excess water, we get:Mass of Evaporating dish + Copper: 40.41 g ± 0.01 gMass of Evaporating dish: 38.71g ± 0.01 gFinal mass of copper: 1.70 g ± 0.01g

Conclusion:The initial mass of copper: 1.49 g ± 0.01gThe final mass of copper: 1.70 g ± 0.01gThe percentage discrepancy:

|experimental value−expected valueexpectedvalue |×100%=1.70−1.491.49

×100%=0.211.49

×100%=0.1409×100%=14.09%=14.1% (3 sig figs)

Notice that that final weight of the copper is more than the initial mass. We have take special care to wipe any water vapor from the bottom of the evaporating dish after taking it off the water bath to get an as accurate measurement of the mass of copper as possible, but there is still surplus mass. I suspect there is some residue zinc sulfate that contributed to this final mass of copper.

Nonetheless, I feel this lab was a success; during this lab, I have familiarized myself with laboratory techniques and now I definitely know the 6 signs of chemical change: gas produced, color change, solid precipitated, heat change, substance disappears, odor produced.


lets start with copper lab report

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