Evidence of a Chemical Change Lab

Mixing in test tube: 1.0 M Copper (II) Nitrate + 1.5 M Sodium Hydroxide

• While mixing, pieces of the mixture made residue on the sides of the test tube

• Mixture got slightly warmer

Mixture’s color too light → Added more Sodium Hydroxide to solution

• The previous color of mixture turned to a darker tone

• Light Blue → Dark Blue

Placed test tube in 500℃ boiling water (heated through a hot plate)

Separating & turning black

• The top is becoming darker (Getting burned?)

Become dust line & becomes water

• Separated from liquid & meniscus 

• Looks like volcano ash

Black color on the bottom, while it is clear on top

Allow mixture in test tube to cool down for two minutes

Then, add 1.5 M Hydrochloric Acid

When adding Hydrolic Acid:

• Turning slight green/blue

• Black stuff fading away

Oxidize? A bit hot at the bottom

Place 10 cm of aluminum wire in test tube with mixture. What happens after a while?

• Bubbling in the aluminum wire occurs

• Gas releasing from the aluminum wire in test tube

• Mixture fizzing

• Part of aluminum wire submerged in water turns reddish-brown

• Hypothetically rusting the aluminum wire through chemical change

• Pieces of reddish-brown aluminum fall off its main structure

• Mixture’s color gets darker

• Test tube gets warmer

After a few minutes:

• Mixture gets colder and clearer

Remove wire from test tube and compare reddish-brown aluminum with Aluminum wire

Aluminum Wire:

• The affected area of aluminum (after the reddish-brown pieces fell) had spots that were darker than the untouched section of the aluminum wire

• Untouched section remained the same

• Color unchanged

• Shape unchanged

• Touched section had changes

• Radius of wire became slightly smaller

• Had spots of darker gray

Reddish-brown aluminum in the test tube:

• Clumped into pieces that lay at the bottom of test tube

• No uniform structure that made up a wire

• Eroded from main structure of original aluminum wire

Copper (II) Nitrate+ Sodium Hydroxide

Copper (II) Hydroxide + Sodium Nitrate

Copper (II) Hydroxide + Heat

Copper (II) Oxide + Water

Copper (II) Oxide + Hydrochloric Acid

Copper (II) Chloride + Water      (NO SOLID)

Aluminum + Copper (II) Chloride

Copper + Aluminum Chloride

Aluminum + Hydrochloric Acid

Hydrogen + Aluminum Chloride (Nonhydrogen gas)

What are some causes of chemical change & the definition? 

Chemical reactions, energy changes, color shifts, gas production, and precipitate formation.  Adding different substances together or combining substances to form new substances can cause chemical changes. 

Identify the substances used or produced in this experiment.  (Hydrogen & …..)

copper (II) nitrate,

sodium hydroxide,

hydrochloric acid. 

sodium nitrate,

copper (II) hydroxide,

copper (II) oxide,

water

aluminum chloride

hydrogen. 

In what 2 ways is heat involved in a chemical change? Cite specific instances from the experiment.  

Heat was first involved in this chemical change through its contribution to forming the products of copper (II) oxide & water.  The second time, it was involved in making the bottom of the test tube warm once it was done forming aluminum chloride.

In the last step of the experiment, where is the aluminum chloride? How did you recover it?

The Aluminum Chloride is in the test tube along with the Copper formed. To recover the Aluminum Chloride, an individual would have to evaporate the water in the test tube.

Copper (II) oxide

Copper (II) water

Copper (II) chloride

Copper (II) nitrate

Copper (II) hydroxide

Black, not a color, not a color, blue, not a color

What are some of the substances used in the experiment that dissolve in water? Which did not?

Hydraulic Acid and Aluminum were substances that dissolved in the water.  The Copper (II) nitrate and Copper (II) chloride did not dissolve in water.  

List four types of observations that indicate when a chemical change has occurred

Observations indicating a chemical change include color change, gas production (bubbles), formation of a precipitate, and temperature change.

Pure Substance 

A material that has a uniform and definite composition, consisting of just one type of particle or chemical. Examples include elements and compounds.

Mixture

A combination of two or more substances that retain their individual properties and can be separated by physical means.

Compound

A substance formed when two or more elements chemically bond together in a fixed ratio, resulting in distinct properties different from the individual elements.

Element

A substance that cannot be broken down into simpler substances by chemical means, consisting of only one type of atom.

Heterogeneous mixture 

A type of mixture where the components are not uniform or evenly distributed, allowing for separation by physical means.

Homogeneous mixture

A mixture in which the composition is uniform throughout, with components that are evenly distributed and not easily distinguishable from one another.

Exothermic

Reaction that releases heat energy to the surroundings.

Endothermic

reaction that absorbs heat energy from the surroundings.

Observations/goals of experiment:

• Observe the types of evidence that indicate a chemical change has taken place

• Infer from the observation of the chemical change that a new substance has been formed

• Identify and record data that shows how heat is involved in chemical change

• Explain why a substance changes can be either a reactant or product in chemical reactions, and why this is necessary for recycling. 

supernate

The liquid that remains above the solid residue after a mixture has settled or been filtered.

precipitate

the solid that forms and settles out of a liquid mixture during a chemical reaction.

Can be broken down into physical & chemical means:

Element, Compound, Mixture

1. N, N,Y

2. N, Y, N

Pure Substances

• Copper metal

• Aluminum metal

• All listed compounds 

Endothermic Reactions

• Heating copper(II) hydroxide → copper(II) oxide 

Exothermic Reactions

• Formation of copper(II) hydroxide 

• Reaction of aluminum with copper(II) chloride and hydraulic acid

compound? 

EVERYTHING ELSE LISTED 

Elements

Aluminum & copper

Heterogeneous Mixtures

• Copper(II) hydroxide precipitate in solution 

• Copper(II) oxide formed after heating 

• Fizzing from Aluminum wire + copper chloride & hydraulic acid

Homogenous mixture

• Copper(II) nitrate 

• Sodium hydroxide

• Hydrochloric acid 

• Copper(II) chloride 

• Aluminum chloride

Precipitates in the lab

Copper hydroxide, copper oxide, copper

All supernates

Sodium nitrate, water, copper chloride, aluminum chloride, hydrogen gas