CHEM 1030 Chapter Notes - Chapter 1: Celsius, Decimal Mark, Significant Figures

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CHEM 1030 Full Course Notes

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Chemistry the study matter and the changes it undergoes. Physical properties: can be observed without changing a substance into another substance, boiling point, density, mass, volume, etc. Chemical properties: can only be observed when a substance is changed into another substance, flammability, corrosiveness, reactivity with acid, etc. Intensive properties: are independent of the amount of the substance that is present, density, boiling point, color, etc. Extensive properties: depend upon the amount of the substance present, mass, volume, energy, etc. Physical changes: changes in matter that do not change the composition of a substance, changes of state, temperature, volume, etc. Chemical changes: changes that result in new substances, combustion, oxidation, decomposition, etc, chemical reactions. In the case of a chemical reaction, the reacting substances are converted to new substances. Compounds: can be broken down into more elemental particles. Metric system: prefixes convert the base units into units that are appropriate for the item being measured.

Related Questions

1.Which of the following is a physical property?

A) ozone reacts with silver to give silver oxide

B) platinum metal does not react with hydrochloric acid

C) the density of lead

E) Sulfur burns in oxygen to form sulfur trioxide

2. Which of the following is a chemical property of gold?

A) is malleable

B) does not react with hydrochloric acid

C) is a good conductor of heat

D) is a good conductor of electricity

3) Which of the following is a physical change?

a) the freezing of water to form ice

B) the inability of gold react with water

C) the burning of paper

D) the sodium metal vigorously with water

E) the reaction of zinc with hydrochloric acid

4. Which one of the following would be classified as a heterogenous mixture?

A) copper nitrate solution

B) mix of table salt and black pepper

C) Salt water

D)brass

E) a sugar solution

5. Which of the following is a chemical change?

A) the boiling of water to form steam

B) crushing of lump of sulfur into yellow powder

C) the reaction of chlorine gas and sodium to form salt

E) hammering zinc into a thin film

6) An extensive property is

A) independent of the quantity of matter observed

B) difficult to measure

C) always strongly dependent on the external conditions

D) dependent on the quantity of matter observed

E) is a unique value regardless of the measurement conditions

7) Which of the following defines or expresses the concepts of accuracy?

A) average of the data

B) differences between the accepted answer and the average value of the data

C) deviation of the average

D) the closest value to the expected answer

E) reproducibility of a measurement

8) Hydrates are:

A) orgainc compounds that contain oxygen together with usual carbon and hydrogen

B) readily soluble in water and release energy

C) concentrated solutions of salts in water

D) moistyre sensitive hygroscopic inorganic salts

E) compounds in which each formula unit has one or more water molecules associated with it

9) Which of the following is the correct defintion of isomer?

A) Isomers are molecules with the same empirical formula but have different isotopes

B) Isomers are molecules that have the same molecular formula but contain different istotopes.

C) Isomers are molecules that have the same molecular formula but different arrangement of atoms in space

D) Isomers are molecules that have the same arrangements of atoms in space but different empirical and molecular formulas

E) Isomes are molecules that have the same empirical formula but different arrangements of atoms in space

10) Most water-soluble compounds of Group 1A or 2A elements are:

A) nonelectrolytes

B) weak electrolyes

C) weak acid

D) strong electrolytes

E) strong acids

11) to precipitate Cd2+(aq) from solution one could add:

A) KI(Aq)

B) NaCl(aq)

C) H2S(aq)

D)HNO3(aq)

E) HCl(aq)

12) Select a statement that best describe the oxidation process

A) in the oxidation process all elements experience an increase in oxidation state

B) in the oxidation process all elements change oxidation state

C) in the oxidation process some elements change their oxidation state

D) in the oxidation process some elements experience oxidation state increase

E) In the oxidation process only oxygen increases its oxidation state.

13. A disproportionation reaction is one in which:

A) the dame substance is oxidized and reduced

B) the equation is not balanced

C) both reactants are reduced

D) water must be added

C) more of one substance reacts than another

14) The energy of molecules of a gas:

A) is the same for all molecules at constant temperture

B) is dependent on concentration

C) increases with an increase in pressure

D) is distributed over a wide rande at constant temperature

E) increase with a decrease in temperture

15. The volume correction term in the van der Waals equation is present because:

A) molecules occupy volume

B) molecules attract each other

C) barometers are inaccurate

D) molecules repel each other

E) molecules are diatomic

Chromatography: Separating Mixtures

Introduction:

Magic marker inks are often mixtures of several compounds. Paper chromatography is a common method of separating various components of a mixture. After separation, you can observe the different colors that make up a particular color of magic marker ink.

You can also calculate a ratio Rf, which compares how far each compound traveled to how far each solvent (substance that dissolves another substance) traveled during the experiment.

Rf = Ds/Df

Ds = Distance traveled by the compound

Df = Distance traveled by the solvent

Materials:

coffee filter, tape, isopropyl alcohol (rubbing alcohol), water, 3 different color magic markers (not permanent); 3 identical tall, narrow drinking glasses; metric ruler, 3 pencils

Pre-lab Questions:

List one extensive and one intensive property of marker ink.

Intensive: Amount Doesn't Matter

Extensive: Amount Matters

An extensive property of marker ink would be volume or ink.

An intensive property of marker ink would be the color of ink.

Define mixture.

A combination of two or more substances that are not chemically combine with one another.

Is tap water a heterogeneous or homogenous mixture? Explain your answer.

Tap water is a homogeneous mixture. I think this because I can see that it has uniform. It doesnât contain any different molecules as well.

Is isopropyl alcohol (rubbing alcohol) a heterogeneous or homogenous mixture? Explain your answer.

I believe rubbing alcohol is a homogeneous mixture. I think this because I can physically see that it has uniform. It also stays in the same phase.

Procedure:

1. Cut 3 strips of coffee filter. Be sure that the strips are much narrower and slightly taller than the drinking glasses.

2. In the center the strips, about 3 cm from one end, place a dot of the marker to be tested. The dots should be about 0.2 cm in diameter and dark enough to be clearly visible.

3. Place about 2 cm of water in each glass.

4. Tape the unmarked end of each strip to the center of a pencil so that the strip hangs down when the pencil is held horizontally.

5. Carefully insert the strips into the glasses, dotted end down. The dot must be above the water, and the sides of the coffee filters cannot touch the sides of the glasses.

6. Let the setup stand for 20 minutes. Follow procedure 8 as your set up stands.

7. Record your observations after 20 minutes in the table below. Measure Df (in cm) for the solvent. Measure the Ds (in cm) for each color that you see on the coffee filter (there may not be three). Calculate the Rf for each color using the equation in the Introduction section.

8. Repeat steps 1â7, except place about 2 cm of isopropyl alcohol (rubbing alcohol) in each glass instead of water.

9. Clean up your work area.

Solvent: isopropyl alcohol (rubbing alcohol)

5. What evidence is there that marker ink is a mixture?

The marker ink is a mixture. The evidence is when the marker ink separated.

6. Each compound in the marker ink is represented by a color. Did one compound travel farther than the others? Explain why you think that this is the case.

Yes, I found out that the darker of the three colors traveled further.

7. Did the compounds travel farther in the water or the isopropyl alcohol (rubbing alcohol)? Explain why you think that this is the case.

The compounds traveled faster in the water than the rubbing alcohol. I think the reason why is because water is smaller on a molecular level versus rubbing alcohol. So it is easier for the dyes to separate.

8. How could you improve upon the accuracy of your Rf measurements?

I feel that accuracy could be improved if we changed the scale measurement to millimeters (mm) instead of cm (centimeters).

Water traveled faster than the rubbing alcohol. I personally think it has to do with something like the size of the molecule like the smaller the molecule the easier it is.

1.A block of metal has dimensions 5.00 cm x 2.50 cm x 3.00 cm. Calculate the volume of the block, showing the answer to the correct number of significant figures and unit.

2.If the block of metal from question 2 has a mass of 405.3 g, what is the density of the metal? Calculate the density, showing the answer to the correct number of significant figures and correct unit.

3.Convert the numerical value of the density in question 2 from units of grams per cubic centimeter (g / cm3) to milligrams per milliliter (mg / mL). Note:

-there are 1000 milligrams in a gram.

-the volume unit cubic centimeter cm3 equals the milliliter mL.

Keep the new density to the same significant figures as you reported in question 2

4.A finely-powdered white solid is known to be homogeneous mixture rather than a pure substance. A sample of this solid completely dissolves in water. Give TWO possible substances that could make up this solid mixture, and briefly explain your choices.

5.If your percent SALT in Lab 2 is relatively low, it can be assumed that some salt did not go into the filtrate (the liquid that passes through the filter paper), but rather may have been trapped with the sand. Explain briefly how you could recover any of this "missing" salt?

6.A brand of aspirin claims to contain 325 mg (1 g = 1000 mg) of aspirin per tablet. In addition to pure aspirin, a tablet also contains a non-active filler. We assume that the tablet contains only these two components: aspirin and filler. If a single tablet weighs 1.17 g, calculate the percent filler. Hint: calculate percent aspirin FIRST using the formula

% aspirin = [ (mass aspirin Ã· mass tablet) x 100], the find % filler. When using this formula, make sure the masses of aspirin and tablet have the same units.

7.Water has a density of 1.00 g/mL, and chloroform has a density of 1.49 g/mL. These two liquids do not mix with each other, but rather, form two layers when combined.

8.Equal volumes of water and chloroform are placed in a beaker. A piece of nylon is dropped in the beaker, and is seen to float the the interface (the boundary) of the two liquid layers.

Give a possible value for the density of nylon, including the correct units. Explain your answer briefly.

9.A procedure similar to that used in Lab 3 was performed to find the density of cyclohexane, which has an actual density of 0.779 g/mL, Due to poor lab technique, an experimental density of only 0.663 g/mL is found. Calculate the percent error for the density. Give your answer to the correct number of significant figures.

10.Two white powders are given to you. One is pure sodium bicarbonate, and the other is baking powder (a mixture of sodium bicarbonate and a weak acid like citric acid). Which single test (NOT counting the visual examination with a hand lens) used in Lab 3 allows you to distinguish sodium bicarbonate from baking powder? Explain your answers completely.

11.Gold has a specific heat of 0.129 J/g^oC. If a piece of gold (initially at 10.0^oC) is dropped into hot water, the final temperature of both the gold and the water is measured as 70.9^oC. If it is known that 4560 J of heat transferred from the hot water to the gold, what is the mass of the piece of gold in grams? Give your answer to the correct number of significant figures.

12.It is stated in the Introduction to Lab 4 that q_water = -q_metal. This equation means that if a hot piece of metal is placed in water, the amount of heat given off by the metal is exactly equal to the amount of heat absorbed by the water. However, this equation is not always accurate, because not all of the heat from the metal necessarily goes to the water. Where else can some of the heat go if it is not absorbed by the water?

13.A certain brand of breakfast cereal claims to have 100 Calories per 28 gram serving. 150.0 grams of cereal are burned using a procedure similar to that used in Lab 4. How many calories of heat are released? Note 1 food Calorie (capital C) = 1000 heat calories (lower case c)

14.The oxalate anion C2O42- is found in many dark green vegetables, including spinach, swiss chard, and collard greens. When cations react with oxalate, the resulting ionic compounds are insoluble in water except Group I A oxalates (e.g. compounds of lithium, sodium, potassium, etc. and oxalate) and ammonium oxalate (NH4)2C2O4. These exceptions are soluble in water.

15.Spinach leaves are cut into small pieces, mashed with small amounts of boiling water, and filtered through filter paper to remove the insoluble spinach material. The resulting aqueous extract contains the oxalate anion.if a small amount of the spinach extract is mixed with a small amount of a calcium acetate solution, Ca(C2H3O2)2(aq), what do you expect will be observed?

16.If a small amount of the spinach extract from question 16 is mixed with a small amount of a potassium acetate solution, KC₂H₃O₂(aq), what do you expect will be observed?

17.If a hot water extract of another vegetable is mixed with calcium acetate solution and a white precipitate is observed, does this automatically indicate the presence of the oxalate anion in this vegetable? Explain your answer.

CHEM 1030 Chapter Notes - Chapter 1: Celsius, Decimal Mark, Significant Figures

CHEM 1030 Full Course Notes

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