(2 Lab Periods) Chemistry 105 Lab

LABORATORY 5: MATTER AND ITS CHANGES

I. THE PERIODIC TABLE

A. ELEMENTS Memorize selected elements. Correct spelling is essential!!!

B. Periods are horizontal rows on the periodic table Groups are vertical columns on the periodic table Group Name IA Alkali Metals IIA Alkaline Earth Metals VIIA Halogens VIIIA Noble Gases

Families are groups (essentially). These elements have similar properities. Diatomic Elementsare those elements that exists as two atoms bonded together

Representative elementsare "A" group elements Properties of metals Properties of nonmetals

Transition elements (metals) are the "B" group elements

Mettaloids are elements with properities that are intermediate between those of metal and nonmetals

Physical States of elements- Elements exists as either a gas (g), liquid (l) or solid (s).

Gases: H2, N2, O2, F2, Cl2, He, Ne, Ar, Kr, Xe, Rn

Liquids: Cs, Fr, Hg, Ga, Br2

4/6/18 1 Symbols and Name of Some Common Elements (Memorize these) Nonmetal Metals Metalloids s Symbol Name Symbol Name Symbol Name H hydrogen Li lithium B boron He helium Be beryllium Si silicon C carbon Na sodium As arsenic N nitrogen Mg magnesium O oxygen Al aluminum F fluorine K potassium Ne neon Ca calcium P phosphorus Mn manganese S sulfur Fe iron Cl chlorine Co cobalt Ar argon Ni nickel Br bromine Cu copper Kr krypton Zn zinc I iodine Rb rubidium Xe xenon Sr strontium Ag silver Cd cadmium Sn tin Ba barium Au gold Hg mercury Pb lead

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PERIODIC TABLE IA II. MATTER-Matter is anything that occupies space and has mass. Symbols and Formulas Symbols represent individual atoms of an element:

H O Cl Br Ag

Formulas represent molecules or units of a compound

H2O CO2 C2H5OH Ca(NO3)2

Molecular mass is the sum of the atomic masses of all of the atoms in the molecule

A. PHYSICAL STATES OF MATTER SOLID LIQUID GAS Attraction between molecules

Movement of molecules

Density

Expansion when heated

Ability to flow Or diffuse

Distance between particles

Compressibility

Made of:

Types of solids

4/6/18 4 B. PHYSICAL PROPERTIES Each substance has a unique set of properties. Physical properties can be seen or measured with out changing the chemical composition.

Other Properties of liquids Surface tension Viscosity Cohesion Adhesion Diffusion

Other Properties of gases Pressure Temperature

C. PHYSICAL CHANGES A physical change alters the physical properties of a substance without altering its chemical composition. There is no new substance Usually when: 1. Changing a sample of matter from one physical state to another

solid -> liquid

liquid -> solid

liquid -> gas

gas -> liquid

solid -> gas

2. Changing the size or shape of the substance

3. Mixing or dissolving two or more substances

D. CHEMICAL PROPERTIES 4/6/18 5 Chemical properties are observed or measure only when it is undergoing a chemical reaction.

E. CHEMICAL CHANGES A chemical change is a process that changes the chemical composition of a substance

1. Examples of chemical reactions

2. Evidence of a chemical reaction occurring A

3. Chemical equations

F. EXAMPLES OF PHYSICAL VS CHEMICAL CHANGES

1. Paper burns to produce CO2 and H2O 2. Gasoline evaporates 3. The statue of liberty turns green 4. Tearing paper 5. A tree stump rots 6. Dissolving a package of jello in water

VII. Types of Particles 4/6/18 6 A. Atoms are the smallest units/particles that can exist that will have the characteristics of the element.

B. Molecules are the smallest unit of two or more atoms covalently bonded together. (more later)

C. An ion is a positively or negatively charged atom or group of atoms

4/6/18 7 VIII. Types of Matter A. Pure Substances Matter with a definite composition a. Element - an element cannot be broken down by simple chemical means. Symbols of Elements:

b. Compound - a compound can be broken down into two or more elements. Two or more elements chemically bonded together. (1) Ionic compounds - (+) and (-) charged ions bonded together by the force of their positive and negative charges Formulas of Compounds:

(2) Molecular compounds - Two or more atoms covalently bonded together (more later) Formulas of Compounds:

B. Mixture – Physical mixture of two or more substances. a. Homogeneous mixture is uniform in appearance and properties throughout. -could consist of 2 or more substances.

b. Heterogeneous mixture has 2 or more physically distinct phases.

4/6/18 8 Examples:

Compounds Mixtures Pure Not pure One kind of particle More than one kind of particle

Can be broken down into component elements only Can be separated by physical change by chemical change

Elements are combined chemically by chemical Parts can be elements or compounds and are not bonds held together by chemical bonds, only by physical attractions Elements no longer have their original properties Elements or compounds that make up the mixture retain their own properties Elements are bonded in a set or definite ratio Element or compound parts can be mixed in any ratio

4/6/18 9 Experiment

I. INTRODUCTION In today's lab you will observe some physical properties of elements and some physical and chemical changes. Background 1) A pure substance is a sample of matter that has a definite, fixed composition, and the same properties throughout the sample. Each pure substance has its own set of characteristic properties.

Physical properties can be observed without changing the chemical composition of the substance. Common physical properties that can be measured without changing the chemical composition are color, melting point, boiling point, solubility and density. Taste and odor are usually considered to be physical properties although they depend on the physiology of the person making the observations.

Physical changes do not cause a change in chemical composition, but only a change in appearance. When a substance simply changes from a solid to a liquid, liquid to a gas or vice-versa (liquid water to solid water, for example) without a change in composition, it is a change in state. This is a physical change. (The three physical states are: gas, liquid, and solid).

Chemical properties describe the ability of a substance to react and change into another substance with a different chemical composition. The new substance would have new properties.

2) Evidence that a chemical change is taking place includes: a. A color change b. A solid product, a precipitate is formed c. A gas is formed d. Energy such as heat, light or electricity is produced.

Purpose: To learn how to classify matter and its changes II. PROCEDURE

Safety goggles must be worn at all times Hydrochloric acid (HCl) and sodium hydroxide (NaOH) can harm eyes, skin, and clothing. Handle with care. Any acid spilled on the skin should be rinsed with a large volume of water for 15 minutes.

Wash your hands before you leave the lab. Do not take reagent bottles from the reagent bench to your work station. Do not pour anything back into a reagent bottle. Offer extra chemical to another student Do not stick anything into a reagent bottle. Always clean glassware and spotplates with distilled/deionized water.

4/6/18 10 A Classifying Physical and Chemical Change:

For the following, record your observations, decide if the change is chemical or physical, and give a reason for your conclusion

Perform the following tests at your lab bench. 1. Your instructor will show you how to properly light a laboratory burner and how to properly obtain chemicals from the reagent bench.

What color is the flame that is correct for most laboratory procedures? ______

2. Do this in the fume hood! Obtain a piece of magnesium ribbon from the reagent bench and place it in the burner, holding it with your crucible tongs.

Do not look directly at the flame. Observation:

Type of Change:______

Evidence/Explanation:

Is a new substance present at the end of this experiment?______After reacted magnesium is cooled put in the trash. 3. Obtain about 2 ml of Copper sulfate solution from the reagent bench. Put it into a test tube. Add about 2 ml of sodium hydroxide solution and mix them together in the tube with your stirring rod. Observation:

Is a new substance present at the end of this experiment?______Pour down the sink.

4/6/18 11 4. In a 50 ml beaker obtain about 10 ml of milk in a beaker and mix with about 3 ml of vinegar. Stir with your glass stirring rod Note: Do not pour any solid down the sink. Observation:

Is a new substance present at the end of this experiment?______Pour down the sink Observe the following demonstrations by the instructor 5.Your instructor will show you a distillation of Copper (II) Sulfate (CuSO4) solution. Observation:

Explanation:

Is a new substance present at the end of this experiment?______

6.Change of state of iodine Observation:

Explanation:

4/6/18 12 7.Electrolysis of water Observation:

8. Reaction of Zinc and sulfur Observation:

9. Reaction of sodium in water Observation:

4/6/18 13 B. Using Chemical and Physical Changes to Identify an Unknown Substance At the reagent bench are samples of 7 common substances. Your instructor will assign you an unknown, which is the same as one of the 7 known substances. Based on the observations of the chemical and physical properties of the known and unknown substances, you will determine the identity of the unknown. Procedures 3-5 do not need to be done in order. You will perform all of the tests on the unknown that you perform on each of the known samples.

1. Observe each sample, including the unknown, and then record your observations as to the color, texture and any other important properties in table 1.

2. In a spot plate place small pea-sized amounts of each substance in 2 different rows of wells. Be careful to note which substance is in which well. Do not use more than a small pea-sized amount, or it will be difficult to perform the tests. (On a paper towel write the name of each substance in the order it is placed in your spot plate, and place this paper towel next to the spot plate.)

3. a. Into the first row of wells of the different substances, put about 1 ml of de-ionized water. See if the substances dissolve completely or partially, or change in any other way. Record any evidence of change that occurs in table 1. b. In the row of wells that contains the substances mixed with water, put 3 drops of universal indicator. Record any evidence of change in table 1. 4. In the other row of wells containing the samples put 3 drops of dilute acetic acid (vinegar) and record any evidence of change in table 1 below.

5. Cover your wire gauze with a piece of the aluminum foil that is set out on the reagent bench. Place about pea-sized amounts of each substance onto the foil covered gauze. Make sure there is plenty of space between each sample on the foil. Place the gauze on the ring stand and ring apparatus that is in the fume hood. Light the burner and place the heat under each sample to see if any change occurs. Record any evidence of change in table 1.

Using the data that you recorded in table 1, determine the identity of the unknown sample and answer the questions that follow the table.

Waste: Rinse spot plates in the sink. Clean spot plates with tap water then deionized water. When aluminum foil has cooled. Wad it up and throw it in the trash.

4/6/18 14 Table 1: Determining the identity of an Unknown substance Appearance Reaction with Reaction with Reaction with Reaction with (1) water (2) universal indicator (3) vinegar (4) heat (5) Sodium Chloride

Sugar (Sucrose)

Baking Powder

Baking Soda (Sodium Bicarbonate) Citric Acid

White Flour

Calcium Carbonate

Unknown #

Unknown # ______Based on you observations in the above table identify the unknown______

Explain the reason for you answer to the above question:

4/6/18 15 C. Classifying compounds elements, heterogeneous and homogeneous mixtures by appearance

On the reagent bench are several samples of various substances. Write the name of the substance, a brief description of its state, color and any other pertinent observation, state if the substance appears homogeneous or heterogeneous and finally classify it as a compound element or mixture. Table 2: Classifying Types of Matter by Appearance

Substance Description Homogeneous Classification : or Compound Element heterogeneous or Mixture Rock Carbon Windex Distilled Water Copper Copper (II) Sulfate Solution Copper (II) Sulfate CuSO4

C12H22O11 Sulfur

Compounds Compounds are groups of atoms of different elements that are chemically bonded together. They do not have the same properties as the original elements. In table 3 are some examples of everyday compounds with their common name, chemical name and formula. Complete the table. Table 3 Common Chemical Formula Symbols of How many of Name Name elements in each element compound

Baking soda Sodium NaHCO3 Bicarbonate

Table salt Sodium NaCl Chloride

Aspirin Acetylsalicylic C9H8O4 Acid

4/6/18 16 D. Classifying Elements by Physical Properties : A number of elements in labeled bottles are on display. Your instructor will show you a sample of sodium. Classify them as metals, nonmetals and those you are unsure of. Put them in a table that shows their name and classification.

Table 4: Classifying Elements by Appearance

Metals Nonmetals Unsure

Once you have completed all of the experiments and observed the demonstrations, draw a “Black box diagram” of one compound, one element and one mixture.

Compound Element Mixture Name of material: Name of material: Name of material: Diagram: Diagram: Diagram:

4/6/18 17 Conclusions and Reflections

Have you learned the difference between compounds, mixtures and elements? If not, what is a question you have that would help you see the difference.

What was it that you did today that helped you see the difference between chemical and physical change?

What is something you are confused about?

Questions: 1. Explain the difference between chemical and physical change? (You can use examples from this lab in your explanation.)

1. What is the difference between zinc and a compound of zinc such as zinc sulfide?

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