Chemistry Experiments

Jared Baltzell, Jacob Feltner, Lindsay Creque, Jaclyn Hood

A. Introduction

a. Primary Objective: Writing Balanced Chemical Equations

Reactants: A substance that takes part in and undergoes change during a reaction.

Products: The compounds that are formed when a reaction goes to completion.

Coefficients: A multiplier or factor that measures some property.

b. Secondary Objective: observing evidence of chemical reactions

The following 4 observations let you know that a chemical reaction has occurred:
i. Formation of a precipitate
ii. Formation of a gas

iii. Change in temperature/ emitting light
iv. Change in color

B. Analysis of Reactions

Experiment 1: Copper (II) sulfate pentahydrate crystals decompose to form copper (II) sulfate and water.

a. We could tell that there was a chemical reaction occurring because there was a change in color and a formation of a gas. The light blue color turned darker and smoke came out of the test tube.

b. The term "hydrate" means a substance that contains water or it's elements.

c. This reaction is decomposition.

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Experiment 2: Potassium iodide reacts with lead (II) nitrate to yield...

a. We could see that a chemical reaction occurred because there was a formation of a precipitate (a yellow powdery substance formed at the bottom of the test tube) and the yellow color turned darker when lead (II) nitrate was added.
b. When you write a balanced equation the words "reacts with" means that you will be mixing two things together. In this experiment we had potassium iodide reacting with lead (II) nitrate.
c. This reaction is a double replacement.
d. 2_KI + Pb(NO3)2 --> 2_KNO3 + PbI2
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Experiment 3: Magnesium reacts with oxygen gas to form...

a. The light emitted was evidence that a chemical reaction had occurred.

b. Since oxygen is a BrINClHOF element, that means it cannot stand as one atom on its own.

c. The type of reaction that occurred in this experiment was synthesis.

d. Balanced equation: 4_Mg + 2_O2 --> 4_MgO
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Experiment 4: Zinc metal reacts with hydrochloric acid to produce...

a. We knew and chemical reaction happened because a gas formed and the liquid started to bubble.
b. Cation- Is a positively charged ion
Anion- Is a negatively charged ion
c. The reaction that happened was a single replacement reaction.
d. The balanced equation is: 2_HCl + Zn --> ZnCl2 + H2
e. The product that was formed is ZnCl2 + H2
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Experiment 5: Hydrogen peroxide breaks down to form water and oxygen gas.

a. We know that there was a chemical change because a gas was formed. When MgO2 was added, it made the solution fizzle.

b. The manganese dioxide is a catalyst. A catalyst is a substance that speeds up a chemical reaction, but it isn’t consumed by the reaction.

c. This reaction is decomposition.

d. MgO2 (above arrow)

2_H2O2 → 2_H2O + O2

e. When the glowing splint went into the test tube, the flame grew brighter. This is because of the O2.

C. Conclusions

a. The following are either chemical or physical:

i. dissolving salt in water is chemical.

ii. melting ice is physical.

iii. milk turning sour is chemical.

iv. burning fireworks is chemical.

v. a 2-liter bottle going flat is physical.

vi. frying an egg is chemical.

b. Symbol: (s) What it means: ionic compounds that won't dissolve at all or will only slightly dissolve are called insoluble which is what (s) stands for. Experiment #1 Chemical used: Copper (II) sulfate pentahydrate crystals

Symbol: (l) What it means: liquid

Symbol: (g) What it means: gas Experiment #4 Chemical used: hydrochloric acid

Symbol: (aq) What it means: soluble Experiment #2 Chemical used: potassium iodide and lead (II) nitrate