1. Chapter 1 Homework Problems (08 08 19) PDF

Preview

Summary

Download 1. Chapter 1 Homework Problems (08 08 19) PDF

Description

George E Arab

Chapter 1 (Introduction to Chemistry) Table of Contents Page Numbers Table of Contents ......................................................................................

1

Important Terms ........................................................................................

2-4

Homework Problems ................................................................................

5 - 15

For Quiz 1a ....................................................................................

5 - 11

For Quiz 1b ....................................................................................

12 - 15

Solutions to the Homework Problems ......................................................

16 - 33

For Quiz 1 a ..................................................................................

16 - 22

For Quiz 1 b .................................................................................

22 - 33

Elements to be Memorized for the Exam ................................................

34

Potential Exam Questions .......................................................................

35 - 38

Solutions to the Potential Exam Questions ..............................................

39 - 49

1

George E Arab

Important Terms I generally do not ask you to define terms, however, I regularly use them in sentences in class and on the tests and quizzes so you must know what they all mean. Chemistry: The study of the nature, properties, and transformations of matter Matter: The physical material that makes up the universe; anything that has mass and occupies space Scientific Method: The systematic process of observation, hypothesis, and experimentation used to expand and refine a body of knowledge. Property: A characteristic useful for identifying a substance or object. (All objects, matter and things have their own unique properties, even you! Color, smell, state(whether a liquid or solid or gas), etc. are all properties) Physical Change: A change that does not affect the chemical makeup of a substance or object. (such as water melting or boiling, or sugar getting dissolved in water) Chemical Change: A change in the chemical makeup of a substance. (such was paper burning) Solid: A substance that has a definite shape and volume. Liquid: A substance that has a definite volume but assumes the shape of its container. Gas: A substance that has neither a definite volume nor a definite shape. State of Matter: The physical state of a substance such as a solid, liquid, or gas. (These are the only three we will discuss in this class, but plasma is a fourth form of matter that you may have heard about as well, and there are many other states of matter that only physicists truly understand) Change of State: The conversion of matter from one state to another. (For example if you boil water it is changing from a liquid to a gas. If you put water in the freezer it is changing states from a liquid to a solid) Pure substance: A substance that has a uniform chemical composition throughout. (Distilled water, pure sugar, gold, and copper are examples of this. It turns out that pure substances are actually quite rare in nature and that most things, including the water we drink is actually a mixture).

2

George E Arab

Mixture: A blend of two or more substances, each of which retains its chemical identity. (sugar water or trail mix would be good examples of this). Homogeneous mixture: A uniform mixture that has the same composition throughout. (sugar water, the air that we breathe, or cool-aid would be good examples of this) Heterogeneous mixture: A nonuniform mixture that has regions of different composition. (Trail mix, concrete, soil, a person, a plant, are good examples of this) Element: A fundamental substance that cannot be broken down chemically into any simpler substances. (examples include gold, copper, silver, lead, oxygen gas, nitrogen gas, argon helium, etc. The periodic table will give you a full list of elements) Chemical Compound: A pure substance that can be broken down into simpler substances by a chemical reaction. (This definition is a complicated way of saying that chemical compounds are made of different elements. Sugar is a pure compound made from the elements carbon, oxygen, and hydrogen. Water is a chemical compound made from oxygen and hydrogen) Chemical Formula: A notation for a chemical compound using element symbols and subscripts to show how many atoms of each element are present. (The chemical formula for water is H2O, The chemical formula for methane is CH4, the chemical formula for table sugar (sucrose) is C12H22O11. Chemical Reaction: A process in which the identity and composition of one or more substances are changed. (examples include putting an electric current in water to get H2 and O2 and the metabolism of sugar by our body to get CO2 and H2O) Reactant: A starting substance that undergoes a change during a chemical reaction. (For the examples listed under chemical reaction, the reactants would be water, and sugar[note that the product of the metabolism of sugar is also water]) Product: A substance formed as the result of a chemical reaction (For the examples listed under chemical reaction, CO2, H2O would be the products of sugar metabolism) Physical Quantity: A physical property that can be measured. (This can be length, distance, mass, weight, temperature, volume, etc) Unit: A defined quantity used as a standard of measurement. (Examples of this are the mile, kilometer, Fahrenheit, Celsius, foot, inch) SI Units: A standardized set of of units defined by the International System of Units. (This was developed to avoid unnecessary confusion so most scientists around the world could work with the same units).

3

George E Arab

Scientific Notation: A number expressed as the product of a number between 1 and 10 multiplied by the number 10 raised to a power. (Examples 9.8 x 10-3, 3.6 x 108, 6.02 x 1023) Mass: A measure of the amount of matter in an object. (This is NOT a weight, the amount of matter in an object will be the same whether on earth, in space, or on the moon. The mass of an object can not change, the weight can.) Weight: A measure of the gravitational force that the earth or other large body exerts on an object. (Even though the mass is staying the same, the weight can change depending upon what gravitational force is acting on it. Example: you weigh less on the moon, but you have the same mass) Significant Figures: The number of meaningful digits used to express a value. (With significant figures, or sig figs you can have a bunch of certain digit followed by one uncertain digit. Ex: 1.002 has three certain digits (the 1, 0, 0) and one uncertain digit (the 2) ). Rounding Off: A procedure used for deleting nonsignificant figures. (This is essentially removing extra uncertain digits after calculations. The calculator can give you a bunch of uncertain digits at the end of a number so you have to round it off. Please make sure you are familiar with the rules for rounding) Factor-label method Dimensional Analysis: A problem solving proceture in which equations are set up so that unwanted units cancel out and only the desired units remain. (example: (10 feet/1)(12 inchs/ 1 foot) = 120 inches ) Conversion Factor: An expression of the numerical relationship between two units. (example 1 inch = 2.54 cm, or 1 inch/2.54 cm) Energy: The capacity to do work or supply heat. Temperature: The measure of the amount of energy in an object. (More specifically it is the measure of kinetic energy in an object. The higher the temperature, the faster the molecules are moving/vibrating.) Specific Heat: The amount of heat that will raise the temperature of 1 g of a substance by 1 °C. Density: The physical property that relates the mass of an object to its volume. [ Density = Mass (g) / Volume (mL or cm3) ] Specific Gravity: The density of a substance divided by the density of water at the same temperature

4

George E Arab

Homework Problems: For Quiz 1a 1. The six elements in blue at the far right of the periodic table are gases at room temperature. The red elements in the middle of the table are the so-called coinage metals. Identify each of these elements using the periodic table inside the front cover of this book. Please provide the name and the symbol for each element. (example: The symbol for oxygen is O, the symbol for iron if Fe)

2. Identify the three elements indicated on the following periodic table. Please provide the name and the symbol for each element. (example: The symbol for oxygen is O, the symbol for iron if Fe)

5

George E Arab

3. The radioactive element indicated on the following periodic table is likely in all of your homes. It is commonly used in smoke detectors. Please provide the name and the symbol for each element. (example: The symbol for oxygen is O, the symbol for iron if Fe)

4. Assume that you have two graduated cylinders, one with a capacity of 5 mL (a) and the other with a capacity of 50 mL (b). Draw a line in each showing how much liquid you would add if you needed to measure 2.64 mL of water. Which cylinder do you think is more precise? Explain using full sentences.

6

George E Arab

5. State the length of the object depicted in the accompanying figure in centimeters (cm) and millimeters (mm) using the appropriate number of significant figures.

6. Assume that you are delivering a liquid sample from a pipette. Figures (a) and (b) show the volume level before and after dispensing the sample, respectively. State the liquid level (in mL) before and after dispensing the sample, and calculate the volume of the sample.

7. What is the difference between precision and accuracy?

7

George E Arab

8. What is the difference between a physical change and a chemical change? 9. Which of the following is a physical change and which is a chemical change? (a) Boiling water (b) Decomposing water by passing an electric current through it (c) Exploding of potassium metal when placed in water (d) Breaking of glass

10. Which of the following is a physical change and which is a chemical change? (a) Making lemonade (lemons + water + sugar) (b) Frying eggs (c) Burning a candle (d) Whipping cream (e) Leaves changing color (f) Fruit ripening

11. Name and describe the three states of matter

12. Name two changes of state and describe what causes each to occur

13. Classify each of the following as a mixture or a pure substance. (a) Pea soup

(d) A multivitamin

(b) The contents of a propane tank

(e) sea water

(c) Urine

(f) Lead

8

George E Arab

14. Which of these terms, (i), homogeneous mixture, (ii) heterogeneous mixture, (iii) element, (iv) chemical compound, applies to the following substances. (a) Gasoline

(e) Blood

(b) soil

(f) Sodium bicarbonate (baking soda)

(c) Distilled Water

(g) pepperoni pizza

(d) Bag of M&M’s

(h) Silicon

15. Hydrogen peroxide (H2O2), often used in solutions to cleanse cuts and scrapes, breaks down to yield water (H2O) and oxygen(O2): 2H2O2 (aq) → 2H2O (l) + O2 (g) (a) Identify the reactants and products (b) Which of the substances are chemical compounds, and which are elements? (c) What is the state of each substance, solid, liquid, gas, or dissolved in water?

16. When sodium metal (Na) is placed in water (H2O), hydrogen gas (H2) and sodium hydroxide (NaOH) are formed. Na (s) + H2O (l) → H2 (g) + NaOH (aq) (a) Identify the reactants and products (b) Which of the substances are chemical compounds, and which are elements? (c) What is the state of each substance, solid, liquid, gas, or dissolved in water?

17. What are the symbols for the following elements? (a) Iodine

(d) Chromium

(b) Iron

(e) Arsenic

(c) Mercury

(f) Silver

9

George E Arab

18. Supply the missing names or symbols for the elements in the spaces provided: example: Au

Gold

(a) N ____________

(d) __________ Calcium

(b) K ____________

(e) __________ Phosphorus

(c) Cl ____________

(f) __________ Manganese

19. Correct the following statements: (a) The symbol for bromine is BR.

(b) The symbol for manganese is Mg.

(c) The symbol for carbon is Ca.

(d) The symbol for potassium is Po.

(e) Carbon dioxide has the formula CO2.

(f) Carbon dioxide has the formula CO2.

(g) Table salt, NaCl is composed of one nitrogen atom and two chlorine atoms.

20. The amino acid, glycine, has the formula C2H5NO2. (a) What elements are present in glycine? (write out their full names)

(b) How many atoms of each element are present in the formula?

(c) How many atoms are contained in two molecules of glycine 10

George E Arab

21. Glucose, a form of sugar, has the formula C6H12O6. (a) What elements are present in glucose?

(b) How many atoms of each element are present in the formula?

(c) How many atoms are contained in five molecules of glucose?

22. Write the formula for: (a) ibuprofen: 13 carbons, 18 hydrogens, and 2 oxygens.

(b) Flonase: 25 carbons, 31 hydrogens, 3 fluorines, 5 oxygens, 1 sulfur

23. The atmosphere consists of a number of permanent gases: oxygen (O2), nitrogen (N2), carbon dioxide (CO2), water vapor (H2O), and argon (Ar). (a) Identify each substance as an element or a compound.

(b) Would you consider the atmosphere to be a heterogeneous or a homogeneous mixture?

11

George E Arab

For Quiz 1b 24. What is the difference between a physical quantity and a number?

25. What are the units used in the SI system to measure mass, volume, length, and temperature? In the metric system?

26. Give the full name of the following units: (a)

cc

(d)

nL

(b)

dm

(e)

mg

(c)

mm

(f)

m3

27. Write the symbol for the following units: (a)

nanogram

(d)

microliter

(b)

centimeter

(e)

deciliter

(c)

milligram

(f)

kilometer

28. How many nanograms are in 1 mg? In 35 pg? (1012 pg or picogram = 1 g) (109 ng = 1 g or 1 ng = 10-9 g) (1000 mg = 1 g) 29. How many microliters(µL) are in 1 L? In 20. mL? (1000 mL = 1 L) (106 µL = 1L or 1 µL = 10-6 L) 30. Express the following numbers in scientific notation with the correct number of significant figures: (a)

9457

(b)

0.000 07

(c)

20,000,000,000 (four significant figures)

(d)

0.012 349

(e)

654.32 12

George E Arab

31.

32.

33.

Convert the following numbers from scientific notation to standard notation: (a)

5.38 x 103

(c)

2.84 x 10-5

(b)

8.207 x 10-2

(d)

7.36 x 104

How many significant figures does each of the following numbers have? (a)

732,401

(d)

355.5

(b)

0.040 0

(e)

70,000

(c)

5.02

(f)

330

How many significant figures are there in each of the following quantities? (a)

The distance from San Francisco to London, UK, 5,351 miles.

(b)

The average body temperature of a cat is 101.5 °F.

(c)

The melting point of gold, 1,948 °F.

(d)

The diameter of an influenza virus, 0.000 01 mm

(e)

The circumference of the moon, 6,786 miles.

34.

Round off each of the numbers in the previous problem to two significant figures and write the number in scientific notation.

35.

The diameter of the earth at the equator is 7926.381 mi. (a)

Round this number to two significant figures and write the answer in scientific notation.

(b)

Round this number to four significant figures and write the answer in scientific notation.

(c)

Round this number to five significant figures and write the answer in scientific notation. 13

George E Arab

36. Perform the following calculations and express the answer to the correct number of significant figures. (Do NOT forget to include the units)

37.

(a)

5280 ft/mi x 6.2 mi

(b)

4.5 m x 3.25 m

(c)

2.50 g ÷ 8.3 g/cm3

(d)

4.70 cm x 6.8 cm x 2.540 cm

Carry out the following conversions: (a)

3.614 mg to nanograms

(b)

12.0 kL to megaliters

(c)

14.4 µm to kilometers

(d)

6.03 x 10-6 cg to nanograms

(e)

174.5 mL to deciliters

(f)

1.5 x 10-2 km to centimeters

38. Express the following quantities in more convenient units by using SI unit prefixes (convenient means no scientific notation is needed, a SI unit is used instead): example: 2.2 x 105 cm can be conveniently written as 2.2 km

39.

(a)

8.97 x 104 g

(b)

2.44 x 10-4 L

(c)

0.000 000 000 64 g

(d)

2.99 x 108 cm

The speed limit of a Canadian highway is 100. km/ h. (3 sig figs) (1.60934 km = 1 mile, 1000 m = 1 km, 100 cm = 1 m, 1 in = 2.54 cm, 1 ft = 12 in) (a)

How many miles per hour is this?

(b)

How many feet per second? 14

George E Arab

40.

The velocity of a bullet fired from a 9 mm hand gun is 1200 ft/s (assume 2 sig figs). (1 mile = 5280 feet, 1 meter = 100 centimeters, refer problem 38 for additional conversion factors) (a)

How many miles per hour is this?

(b)

How many meters per second?

41.

Aluminum has a specific heat of 0.215 cal/ (g ·°C). When 25.7 cal (108.5 J) of heat is added to 18.4 g of aluminum at 20.0 °C, what is the final temperature of the aluminum?

42.

Calculate the specific heat of copper if it takes 23 cal (96 J) to heat a 5.0 g sample from 25 °C to 75 °C.

43.

Aspirin has a density of 1.40 g/cm3. What is the volume in cubic centimeters of a tablet weighing 250. mg?

44.

What is the density of lead (in g/ cm3) if a rectangular bar measuring 0.500 cm in height, 1.55 cm in width, and 25.00 cm in length has a mass of 220.9 g?

45.

Drug dosages are typically prescribed in units of milligrams per kilogram of body weight. A new drug has a recommended dosage of 9.0 mg/ kg. (1 pound = 453.6 grams ) (a)

How many milligrams would a 130 lb woman have to take to obtain this dosage?

(b)

How many 125 mg tablets should a 40 lb child take to receive the recommended dosage?

46.

A clinical report gave the following data from a blood analysis: iron, ...