Chemical Reactions Lab
Paige, Julie, Caleb, Evan
Definition of chemical reactions
- Reactants- Any substance that undergoes a chemical change in a reaction
- Products- A substance obtained from another substance through chemical change
- Coefficients- A number that is constant for a given substance
b. Signs of a chemical reaction:
Bubbles - Reaction creating a gas
Precipitate is formed
B. Analysis of Reactions
Experiment 1: copper (II) sulfate pentahydrate crystals decompose to form copper (II) sulfate and water.
- The evidence that we saw that led us to believe it was a chemical reaction was the changing of color and a new chemical was formed after setting it on fire; also its not reversible.
b. The definition for hydrate is a substance formed when water combines with another substance.
d. CuSO45H2O -> CuSO4 + 5H2O
Experiment 2: Potassium iodide reacts with lead(II) to yield lead iodide and potassium
We put a little bit of potassium iodide into a test tube, and added a few millimeters of lead(II) nitrate solution.
Observations: The mixture turned a neon yellow.
Bubbles were formed and it looks “chalky”
-We believe this was a chemical reaction because bubbles were formed, and bubbles is an indication of a chemical reaction.
Balanced Equation: 2KI + Pb(NO3)2 -> PbI2 + 2KNO3
Experiment 3:Magnesium reacts with oxygen gas to form...
Observations: Light a white bright color
- It was a chemical reaction because light and heat was emitted
Observations: Emitted a bright white light when burnt
Shattered when it was done burning
b. That oxygen is a lone element that has 2 atoms when by itself
Experiment 4:Zinc metal reacts with hydrochloric acid to produce…
- We think it was a reaction because bubbles were emitted and it created a flammable gas
- Cation- an Ion with a positive charge
Anion- an Ion with a negative charge
c. Single replacement
d. Hydrogen gas
Experiment 5:Hydrogen peroxide breaks down to form water and oxygen gas.
- Bubbles were formed, a new substance was created and its irreversible
- Catalyst- A substance that speeds up a chemical reaction
- The oxygen gas igniting or providing fuel for the glowing splint
- Identify the following as Physical or Chemical changes
- i. Dissolving Salt in Water- Physical
- ii. Melting Ice- Physical
- iii. Milk Turning Sour- Chemical
- iv. Burning Fireworks- Chemical
- v. A 2-Liter Bottle Going Flat- Chemical
- vi. Frying an Egg- Chemical
What it means