Chemistry Review Questions
(2) Make the following temperature conversions: a. 78.1 ° C to kelvins c. 489 K to ° C b. 775 K to ° C d. 24.3 ° C to kelvins
( a) 195 K; ( b) 502 ° C; ( c) 216 ° C; ( d) 297 K
(2) Write each of the following numbers in standard scientific notation. a. 1/0.00032 e. ( 10^5)( 10^4)( 10^4)/( 10^2) b. 10^3 / 10^3 f. 43.2/( 4.32 10^5) c. 10^3/10^3 g. ( 4.32*10^5)/ 432 d. 1/55,000 h. 1/( 105^)( 10^6)
( a) 3.1 *103; ( b) 1 *10^6; ( c) 1 or 1 *10^0; ( d) 1.8 *10^5; ( e) 1* 10^7; ( f) 1.00* 10^6; ( g) 1.00 *10^7; ( h) 1 *10^1
(4) How many electrons are present in each of the following ions? a. Se2- c. Cr3+ e. Bi3+ b. Br- d. Rb+ f. Cu2+
( a) 36; ( b) 36; ( c) 21; ( d) 36; ( e) 80; ( f) 27
(2) Round off each of the following numbers to three significant digits, and express the result in standard scientific notation. a. 0.004175 10 3 b. 38,652 c. 0.000000000000000000000000000009109 d. 5.455 106
( a) 4.18*10^6; ( b) 3.87 *10^4; ( c) 9.11*10^30; ( d) 5.46*10^6
(2) Perform each of the following conversions, being sure to set up the appropriate conversion factor in each case. a. 4.21 ft to inches b. 37.3 in. to feet c. 45.2 cm to millimeters d. 761.2 mm to centimeters e. 1.25 L to quarts f. 4.21 qt to pints g. 6.21 kg to pounds h. 1.75 lb to ounces
( a) 50.5 in.; ( b) 3.11 ft; ( c) 452 mm; ( d) 76.12 cm; ( e) 1.32 qt; ( f) 8.42 pt; ( g) 13.7 lb; ( h) 28.0 oz
(2) Write each of the following numbers as " ordinary" decimal numbers. a. 6.244 103 d. 1.771 10^4 b. 9.117 10^2 e. 5.451 10^2 c. 8.299 10^1 f. 2.934 10^5
( a) 6244; ( b) 0.09117; ( c) 82.99; ( d) 0.0001771; ( e) 545.1; ( f) 0.00002934
(4) Based on the following word descriptions, write the formula for each of the indicated substances. a. a compound whose molecules contain twice as many oxygen atoms as carbon atoms b. a compound whose molecules contain an equal number of carbon and oxygen atoms c. a compound in which there is an equal number of calcium and carbon atoms but there are three times as many atoms of oxygen as of the other two elements d. a compound whose molecules contain twice as many hydrogen atoms as sulfur atoms and four times as many oxygen atoms as sulfur atoms e. a compound in which there are twice as many chlorine atoms as barium atoms f. a compound in which there are three sulfur atoms for every two aluminum atoms
( a) CO2; ( b) CO; ( c) CaCO3; ( d) H2SO4; ( e) BaCl2; ( f) Al2S3
(5) Write the formula for each of the following substances. a. calcium hydrogen sulfate b. zinc phosphate c. iron( III) perchlorate d. cobaltic hydroxide e. potassium chromate f. aluminum dihydrogen phosphate g. lithium bicarbonate h. manganese( II) acetate i. magnesium hydrogen phosphate j. cesium chlorite k. barium peroxide l. nickelous carbonate
( a) Ca( HSO4) 2; ( b) Zn3( PO4) 2; ( c) Fe( ClO4) 3; ( d) Co( OH) 3; ( e) K2CrO4; ( f) Al( H2PO4) 3; ( g) LiHCO3; ( h) Mn( C2H3O2) 2; ( i) MgHPO4; ( j) CsClO2; ( k) BaO2; ( l) NiCO3
(4) Correct each of the following misstatements from Dalton's atomic theory. a. Elements are made of tiny particles called molecules. b. All atoms of a given element are very similar. c. The atoms of a given element may be the same as those of another element. d. A given compound may vary in the relative number and types of atoms depending on the source of the compound. e. A chemical reaction may involve the gain or loss of atoms as it takes place.
( a) Elements are made of tiny particles called atoms. ( b) All atoms of a given element are identical; ( c) The atoms of a given element are different from those of any other element; ( d) A given compound always has the same numbers and types of atoms; ( e) Atoms are neither created nor destroyed in chemical processes. A chemical reaction simply changes the way the atoms are grouped together.
(4) Indicate whether each of the following statements is true or false. If false, correct the statement so that it becomes true. a. Rutherford's bombardment experiments with metal foil suggested that the alpha particles were being deflected by coming near a large, negatively charged atomic nucleus. b. The proton and the electron have similar masses but opposite electrical charges. c. Most atoms also contain neutrons, which are slightly heavier than protons but carry no charge.
( a) False; Rutherford's bombardment experiments with metal foil suggested that the particles were being deflected by coming near a dense, positively charged atomic nucleus; ( b) False; the proton and the electron have opposite charges, but the mass of the electron is much smaller than the mass of the proton; ( c) True
(5) Write the formula for each of the following acids. a. hydrocyanic acid e. hypochlorous acid b. nitric acid f. hydrobromic acid c. sulfuric acid g. bromous acid d. phosphoric acid h. hydrofluoric acid
( a) HCN; ( b) HNO3; ( c) H2SO4; ( d) H3PO4; ( e) HClO or HOCl; ( f) HBr; ( g) HBrO2; ( h) HF
(5) Write the formula for each of the following simple binary ionic compounds. a. magnesium fluoride b. ferric iodide c. mercuric sulfide d. barium nitride e. plumbous chloride f. stannic fluoride g. silver oxide h. potassium selenide
( a) MgF2; ( b) FeI2; ( c) HgS; ( d) Ba3N2; ( e) PbCl2; ( f) SnF4; ( g) Ag2O; ( h) K2Se
(5) Write the formula for each of the following nitrogen-containing polyatomic ions, including the overall charge of the ion. a. nitrate b. nitrite c. ammonium d. cyanide
( a) NO3- ; ( b) NO2- ; ( c) NH4+ ; ( d) CN-
(5) Give the name of each of the following polyatomic ions. a. NH4+ d. HSO3- b. H2PO4- e. ClO4- c. SO4 2- f. IO3-
( a) ammonium ion; ( b) dihydrogen phosphate ion; ( c) sulfate ion; ( d) hydrogen sulfite ion ( bisulfite ion); ( e) perchlorate ion; ( f) iodate ion
(5) Write the name of each of the following binary com-pounds of nonmetallic elements. a. ClF5 d. N2O3 b. XeCl2 e. I2Cl6 c. SeO2 f. CS2
( a) chlorine pentafluoride; ( b) xenon dichloride; ( c) selenium dioxide; ( d) dinitrogen trioxide; ( e) diiodine hexachloride; ( f) carbon disulfide
(5) Write the name of each of the following ionic sub-stances, using - ous or - ic endings to indicate the charge of the cation. a. CoCl3 d. SnCl4 b. FeBr2 e. HgI2 c. PbO2 f. FeS
( a) cobaltic chloride; ( b) ferrous bromide; ( c) plumbic oxide; ( d) stannic chloride; ( e) mercuric iodide; ( f) ferrous sulfide
(5) Write the name of each of the following ionic sub-stances, using the system that includes a Roman numeral to specify the charge of the cation. a. CuCl2 d. Hg2O b. Cr2O3 e. AuBr3 c. HgCl2 f. MnO2
( a) copper( II) chloride; ( b) chromium( III) oxide; ( c) mercury( II) chloride; ( d) mercury( I) oxide; ( e) gold( III) bromide; ( f) manganese( IV) oxide
(5) In each of the following, identify which names are in-correct for the given formulas, and give the correct name. a. MnCl2, manganese( II) chloride b. Cu2O, copper( II) oxide c. K2O, potassium( I) oxide d. ZnS, zinc sulfide e. Rb2S, rubidium( II) sulfide
( a) correct; ( b) incorrect, copper( I) oxide; ( c) incorrect; potassium oxide; ( d) correct; ( e) incorrect, rubidium sulfide
(5) Name each of the following binary compounds, us-ing the periodic table to determine whether the com-pound is likely to be ionic ( containing a metal and a nonmetal) or nonionic ( containing only nonmetals). a. PbS2 d. SnF4 b. PbS e. Cl2O7 c. SiO2 f. Co2S3
( a) lead( IV) sulfide, plumbic sulfide; ( b) lead( II) sulfide, plumbous sulfide; ( c) silicon dioxide; ( d) tin( IV) fluoride, stannic fluoride; ( e) dichlorine heptoxide; ( f) cobalt( III) sulfide, cobaltic sulfide
(5) Give the name of each of the following simple binary ionic compounds. a. LiCl d. AlI3 b. BaF2 e. MgS c. CaO f. Rb2O
( a) lithium chloride; ( b) barium fluoride; ( c) calcium oxide; ( d) aluminum iodide;
(3) Classify each of the following as a physical or chemical change or property. a. A fireplace poker glows red when you heat it in the fire. b. A marshmallow turns black when toasted too long in a campfire. c. Hydrogen peroxide dental strips will make your teeth whiter. d. If you wash your jeans with chlorine bleach, they will fade. e. If you spill some nail polish remover on your skin, it will evaporate quickly. f. When making ice cream at home, salt is added to lower the temperature of the ice being used to freeze the mixture. g. A hair clog in your bathroom sink drain can be cleared with drain cleaner. h. The perfume your boyfriend gave you for your birthday smells like flowers. i. Mothballs pass directly into the gaseous state in your closet without first melting. j. A log of wood is chopped up with an axe into smaller pieces of wood. k. A log of wood is burned in a fireplace.
( a) physical; ( b) chemical; ( c) chemical; ( d) chemical; ( e) physical; ( f) physical; ( g) chemical; ( h) physical; ( i) physical; ( j) physical; ( k) chemical
(3) Classify the following as mixtures or pure substances. a. the sugar you just put into your coffee while studying b. the perfume you dab on before you go on a date c. the black pepper you grind onto your salad at dinner d. the distilled water you use in your iron so it won't get clogged
( a) primarily a pure compound, but fillers and anti- caking agents may have been added; ( b) mixture; ( c) mixture; ( d) pure substance
(5) Name each of the following compounds, which contain polyatomic ions. a. NaMnO4 d. Ca( ClO) 2 b. AlPO4 e. BaCO3 c. CrCO3 f. CaCrO4
( a) sodium permanganate; ( b) aluminum phosphate; ( c) chromium( II) carbonate, chromous carbonate; ( d) calcium hypochlorite; ( e) barium carbonate; ( f) calcium chromate
(7) On the basis of the general solubility rules given in Table 7.1, predict which of the following substances are likely to be appreciably soluble in water. Indicate which specific rule( s) led to your conclusion. a. BaCl2 e. K2CO3 b. NH4C2H3O2 f. Au( NO3) 3 c. Na2S g. ZnSO4 d. Fe( OH) 3 h. Fe2S3
( a) soluble; Rule 3; ( b) soluble; Rule 2; ( c) soluble; Rule 2; ( d) insoluble; Rule 5; ( e) soluble; Rule 2; ( f) soluble; Rule 1; ( g) soluble; Rule 4; ( h) insoluble; Rule 6
(4) For the following ions, indicate whether electrons must be gained or lost from the parent neutral atom, and how many electrons must be gained or lost. a. O2- c. Cr3+ e. Rb+ b. P3- d. Sn2+ f. Pb2+
( a) two electrons gained; ( b) three electrons gained; ( c) three electrons lost; ( d) two electrons lost; ( e) one electron lost; ( f) two electrons lost
(2) When a large or small number is written in standard scientific notation, the number is expressed as the product of a number between 1 and 10, multiplied by the appropriate power of 10. For each of the follow-ing numbers, indicate what power of 10 would be appropriate when expressing the numbers in stan-dard scientific notation. a. 82,350 b. 0.009375 c. 251 d. 0.000000000000000000000000000009109
(a) 10^4; (b) 10^3; (c) 10^2; (d) 10^30
(2) Rewrite each of the following as an " ordinary" decimal number. a. 2.789 10^3 b. 2.789 10^3 c. 9.3 10^7 d. 4.289 10^1 e. 9.999 10^4 f. 9.999 10^5
(a) 2789; (b) 0.002789; (c) 93,000,000; (d) 42.89; (e) 99,990; (f) 0.00009999
Balance each of the following chemical equations. a. Ba( NO3) + 2( aq) Na2CrO4( aq) = BaCrO4( s) + NaNO3( aq) b. PbCl2( aq) + K2SO4( aq) = PbSO4( s) + KCl( aq) c. C2H5OH( l) + O2( g) = CO2( g) + H2O( l) d. CaC2( s) + H2O( l) = Ca( OH)2(s) + C2H2( g) e. Sr( s) + HNO3( aq) = Sr( NO3)2(aq) + H2( g) f. BaO2( s) + H2SO4( aq) = BaSO4( s) + H2O2( aq) g. AsI3( s) = As( s) + I2( s) h. CuSO4(aq) + KI( s) = CuI( s) + I2( s) + K2SO4( aq)
(a) Ba( NO3)2(aq) + Na2CrO4(aq) = BaCrO4(s) 2NaNO3( aq); (b) PbCl2(aq) + K2SO4(aq) = PbSO4(s) + 2KCl(aq); (c) C2H5OH(l) + 3O2(g) = 2CO2(g) + 3H2O(l); (d) CaC2(s) + 2H2O(l) = Ca(OH)2(s) + C2H2(g); (e) Sr(s) + 2HNO3(aq) S= Sr(NO3)2(aq) + H2(g); (f) BaO2(s) + H2SO4(aq) = BaSO4(s) + H2O2(aq); (g) 2AsI3(s) = 2As(s) + 3I2(s); (h) 2CuSO4(aq) + 4KI(s) = 2CuI(s) + I2(s) 2K2SO4(aq)
(7) Write balanced net ionic equations for the reactions that occur when the following aqueous solutions are mixed. If no reaction is likely to occur, so indicate. a. calcium nitrate and sulfuric acid b. nickel( II) nitrate and sodium hydroxide c. ammonium sulfide and iron( III) chloride
(a) Ca2^+(aq) + SO4^2-(aq) = CaSO4(s); (b) Ni^2+(aq) + 2OH^-(aq) = Ni(OH)2(s); (c) 2Fe^3+(aq) + 3S^2(aq) = Fe2S3(s)
(2) Will the power of 10 have a positive, negative, or zero exponent when each of the following numbers is rewritten in standard scientific notation? a. 0.9091 c. 9091 b. 9.091 d. 0.00000009091
(a) negative; (b) zero; (c) positive; (d) negative
(2) By how many places must the decimal point be moved, and in which direction, to convert each of the following to standard scientific notation? a. 5993 d. 62.357 b. 72.14 e. 0.01014 c. 0.00008291 f. 324.9
(a) three places to the left; (b) one place to the left; (c) five places to the right; (d) one place to the left; (e) two places to the right; (f) two places to the left
(4) Simple negative ions formed from single atoms are given names that end in _____.
-ide
(2) The radius of an atom is on the order of 10 10 m. What is this radius in centimeters? in inches? in nanometers?
1*10^8 cm; 4*10^9 in.; 0.1 nm
(2) If a solid block of glass, with a volume of exactly 100 in. 3, is placed in a basin of water that is full to the brim, then ____ of water will overflow from the basin.
100 in. 3
(4) How many elements are presently known? How many of these elements occur naturally, and how many are synthesized artificially? What are the most common elements present on the earth?
116 elements are presently known; 88 occur naturally; the remainder are manmade.
(2) The freezing point of water is ____K.
273
(4) An ion that has three more protons in the nucleus than there are electrons outside the nucleus will have a charge of ______.
3+
(2) Los Angeles and Honolulu are 2558 mi apart. What is this distance in kilometers?
4117 km
(5) What is a binary chemical compound? What are the two major types of binary chemical compounds? Give three examples of each type of binary compound.
A binary chemical compound contains only two elements; the major types are ionic ( compounds of a metal and a non-metal) and nonionic or molecular ( compounds between two nonmetals). Answers depend on student responses.
(7) What is a decomposition reaction? Give an example. Can such reactions also be classified in other ways?
A decomposition reaction is one in which a given compound is broken down into simpler compounds or constituent elements.
(7) When writing the chemical equation for a reaction, how do you indicate that a given reactant is dissolved in water? How do you indicate that a precipitate has formed as a result of the reaction?
A reactant in aqueous solution is indicated with ( aq); formation of a solid is indicated with ( s).
(1) Differentiate between a "theory" and a "scientific theory"
A theory ( model) is a set of tested hypotheses that gives an overall explanation of some part of nature. A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation.
(1) Scientific models do not describe reality. They re simplifications and therefore incorrect at some level. So why are models useful
A theory (a model) is a well tested argument that is not 100% accurate, but they are widely accepted and non disputable
(4) A given compound always contains the same relative masses of its constituent elements. How is this re-lated to the relative numbers of each kind of atom present?
According to Dalton, all atoms of the same element are identical; in particular, every atom of a given element has the same mass as every other atom of that element. If a given com-pound always contains the same relative numbers of atoms of each kind, and those atoms always have the same masses, then the compound made from those elements always contains the same relative masses of its elements.
(2) Give several examples of how prefixes are used in the metric system to indicate quantities that are multiples or divisions of the fundamental units of the metric system.
Answer depends on the student's examples.
(4) Are all atoms of the same element identical? If not, how can they differ?
Atoms of the same element ( atoms with the same number of protons in the nucleus) may have different numbers of neutrons, and so will have different masses.
(6) What does " balancing" an equation accomplish?
Balancing an equation ensures that no atoms are created or destroyed during the reaction. The total mass after the reaction must be the same as the total mass before the reaction.
(3) In a sample of a gaseous substance, more than 99% of the overall volume of the sample is empty space. How is this fact reflected in the properties of a gaseous sub-stance, compared with the properties of a liquid or solid substance?
Because gases are mostly empty space, they can be compressed easily to smaller volumes. In solids and liquids, most of the sample's bulk volume is filled with the molecules, leaving little empty space.
(6) Small cuts and abrasions on the skin are frequently cleaned using hydrogen peroxide solution. What evidence is there that treating a wound with hydrogen peroxide causes a chemical reaction to take place?
Bubbling takes place as the hydrogen peroxide chemically de-composes into water and oxygen gas.
(3) Which of the following does not represent a physical property/ change? a. Elemental sulfur boils at 445 ° C. b. Elemental sulfur is yellow in its most common form. c. Elemental sulfur burns with a dark blue flame in the air to form a gaseous material. d. Elemental sulfur is rigid and hard.
C
(5) Carbon occurs in several common polyatomic anions. List the formulas of as many such anions as you can, along with the names of the anions.
CN- , cyanide; CO3 2- , carbonate; HCO3- , hydrogen carbon-ate; C2H3O2- , acetate
(3) Elemental bromine reacts vigorously with elemental sodium metal to form a white solid. Does this characteristic of elemental bromine represent a physical or a chemical property?
Chemical
(3) What is a compound? What are compounds composed of? What is true about the composition of a com-pound, no matter where we happen to find the com-pound?
Compounds consist of two or more elements combined together chemically in a fixed composition, no matter what their source may be. For example, water on earth consists of molecules containing one oxygen atom and two hydrogen atoms. Water on Mars ( or any other planet) has the same composition.
(3) Describe how the process of filtration could be used to separate a mixture into its components. Give an example.
Consider a mixture of salt ( sodium chloride) and sand. Salt is soluble in water; sand is not. The mixture is added to water and stirred to dissolve the salt, and is then filtered. The salt solution passes through the filter; the sand remains on the filter. The water can then be evaporated from the salt.
(2) Which metric system unit is most appropriate for measuring the distance between two cities? a. meters c. centimeters b. millimeters d. kilometers
D
(2) What property of density makes it useful as an aid in identifying substances?
Density is a characteristic property of a pure substance.
(4) The two most common elemental forms of carbon are graphite and ____.
Diamond
(7) What is a " driving force"? What are some of the driving forces discussed in this section that tend to make reactions likely to occur? Can you think of any other possible driving forces?
Driving forces are types of changes in a system that pull a re-action in the direction of product formation; driving forces include formation of a solid, formation of water, formation of a gas, and transfer of electrons.
(3) During a filtration or distillation experiment, we separate a mixture into its individual components. Do the chemical identities of the components of the mixture change during such a process? Explain.
Each component of the mixture retains its own identity during the separation.
(4) Ions are produced when an atom gains or loses _____.
Electrons
(2) On which temperature scale (° F, ° C, or K) does 1 degree represent the smallest change in temperature?
Fahrenheit
(2) The ____ point of water is at 32° on the Fahrenheit temperature scale.
Freezing/melting
(3) Matter in the ____ state has no shape and fills completely whatever container holds it.
Gaseous
(3) Give three examples of heterogeneous mixtures and three examples of solutions that you might use in everyday life.
Heterogeneous mixtures: salad dressing, jelly beans, the change in my pocket; solutions: window cleaner, shampoo, rubbing alcohol
(6) When balancing chemical equations, beginning students are often tempted to change the numbers within a formula ( the subscripts) to balance the equation. Why is this never permitted? What effect does changing a subscript have?
If you changed the subscripts, you end up changing the actual element/compound.
(3) How do the properties of a compound, in general, com-pare to the properties of the elements that constitute it? Give an example of a common compound and the elements of which it is composed to illustrate your answer.
In general, the properties of a compound are very different from the properties of its constituent elements. For example, the properties of water are altogether different from the properties of the elements ( hydrogen gas and oxygen gas) that make it up.
(3) Gases and ___ take on the shape of the container in which they are located.
Liquids
(6) These days many products are available to whiten teeth at home. Many of these products contain a per-oxide that bleaches stains from the teeth. What evidence is there that the bleaching process is a chemical reaction?
Most of these products contain a peroxide, which decomposes and releases oxygen gas.
(2) How many digits after the decimal point should be reported when the calculation ( 10,434 9.3344) is performed?
None
(1) Describe how you would set up an experiment to test the relationship between completion of assigned homework and the final grade you receive in the course.
Recognize the problem and state it clearly; propose possible solutions or explanations; decide which solution/ explanation is best through experiments.
(4) Who was the first scientist generally accredited with putting the study of chemistry on a firm experimental basis?
Robert Boyle
(5) We indicate the charge of a metallic element that forms more than one cation by adding a _____ after the name of the cation.
Roman Numeral
(4) Why does a solution of sodium chloride in water conduct an electric current, whereas a solution of sugar in water does not?
Sodium chloride is an ionic compound, consisting of Na and Cl ions. When NaCl is dissolved in water, these ions are set free and can move independently to conduct the electric cur-rent. Sugar crystals, although they may appear similar visually, contain no ions. When sugar is dissolved in water, it dissolves as uncharged molecules. No electrically charged species are present in a sugar solution to carry the electric current.
(6) When indicating the physical state of a reactant or product in a chemical equation, how do we indicate that a reactant is a solid? A liquid? A gaseous substance?
Solid, ( s); liquid, ( l); gas, ( g)
(5) When we write the formula for an ionic compound, we are merely indicating the relative numbers of each type of ion in the compound, not the presence of " molecules'' in the compound with that formula. Explain.
Some substances do not contain molecules; the formula we write reflects only the relative number of each type of atom present.
(7) What are spectator ions? Write an example of an equation in which spectator ions are present and identify them.
Spectator ions are ions that remain in solution during a precipitation/ double- displacement reaction.
(3) A sample of matter that is " rigid" has ( stronger/ weaker) forces among the particles in the sample than does a sample that is not rigid.
Stronger
(1) Make five qualitative and five quantitative observations about the room in which you now sit
The answer depends on the student's experience
(4) Which particles in an atom are most responsible for the chemical properties of the atom? Where are these particles located in the atom?
The electrons; outside the nucleus
(4) What two common types of particles are found in the nucleus of the atom? What are the relative charges of these particles? What are the relative masses of these particles?
The protons and neutrons are found in the nucleus. The protons are positively charged; the neutrons have no charge. The protons and neutrons each weigh approximately the same.
(2) Why can the length of the pin shown in Figure 2.5 not be recorded as 2.850 cm?
The scale of the ruler is marked to the nearest tenth of a centimeter. Writing 2.850 would imply that the scale was marked to the nearest hundredth of a centimeter ( and that the zero in the thousandths place had been estimated).
(7) How do chemists know that the ions behave independently of one another when an ionic solid is dis-solved in water?
The simplest evidence is that solutions of ionic substances conduct electricity.
(7) What is meant by a strong base? Are the strong bases also strong electrolytes? Explain.
The strong bases are those hydroxide compounds that dissociate fully when dissolved in water. The strong bases that are highly soluble in water ( NaOH, KOH) are also strong electrolytes.
(4) Why must the total number of positive charges in an ionic compound equal the total number of negative charges?
The total number of positive charges must equal the total number of negative charges so that the crystals of an ionic compound have no net charge. A macroscopic sample of com-pound ordinarily has no net charge.
(7) When the ionic solute MgCl2 is dissolved in water, what can you say about the number of chloride ions present in the solution compared to the number of magnesium ions in the solution?
There are twice as many chloride ions as magnesium ions.
(2) What does it mean to say that every measurement we make with a measuring device contains some measure of uncertainty?
Typically we read the scale on measuring devices to 0.1 unit of the smallest scale division on the device. We estimate this final significant figure, which makes the final significant figure in the measurement uncertain.
(4) On the basis of the element's location in the periodic table, indicate what simple ion each of the following elements is most likely to form. a. P c. At e. Cs b. Ra d. Rn f. Se
a) P3- ; ( b) Ra2- ; ( c) At- ; ( d) no ion; ( e) Cs+ ; ( f) Se2-
(5) Name each of the following acids. a. HOCl e. HBrO4 b. H2SO3 f. H2S c. HBrO3 g. H2Se d. HOI h. H3PO3
a) hypochlorous acid; ( b) sulfurous acid; ( c) bromic acid; ( d) hypoiodous acid; ( e) perbromic acid; ( f) hydrosulfuric
(7) For each of the following precipitation reactions, complete and balance the equation, indicating clearly which product is the precipitate. If no reaction would be expected, so indicate. a. Na2CO3( aq) + K2SO4( aq) = b. CuCl2( aq) + ( NH4) + 2CO3( aq) = c. K3PO4( aq) + AlCl3( aq) =
a. no precipitate b. 2NH4Cl(aq)+ CuCO3(s) c. 3KCl(aq) + AlPO4(s)
(2) How many significant figures are understood for the numbers in the following definition: 1 mi 5280 ft?
an infinite number, a definition
(6) In an ordinary chemical reaction, ____ are neither created nor destroyed.
atoms
(5) In naming ionic compounds, we always name the ____ first.
cation ( positive ion)
(3) _____ can be broken down into the component elements by chemical changes.
compounds
(3) What is the chief factor that determines the physical state of a sample of matter?
forces among the particles in the matter
(2) The most common units for density are ____.
g/ cm3 ( g/ mL)
(3) From the information given above, indicate one physical property of magnesium metal.
malleable; ductile
(4) The proton and the ( electron/ neutron) have almost equal masses. The proton and the ( electron/ neutron) have charges that are equal in magnitude but opposite in nature.
neutron; electron
(4) The tendency to gain electrons is a fundamental property of the _____ elements.
nonmetallic
(7) Reactions involving the combustion of fuel sub-stances make up a subclass of reactions.
oxidation- reduction
(5) Many acids contain the element ___ in addition to hydrogen.
oxygen
