AP CHEMISTRY SUMMER PACKET 2015

Transcription

1 AP CHEMISTRY SUMMER PACKET 2015

2 Welcome to AP Chemistry! This packet is intended to just remind you of the basic concepts we covered in PreAP. For those of you who are seniors next year, you will need a little more refreshing since you had PreAP your sophomore year. You may write your answers on the packet, and you do not need to answer anything in complete sentences. If the questions contain a problem to solve, you must show the work to receive full credit. Remember the little things, like, rounding to correct sig. figs., cancellation of units, and putting correct units on your final answer. Only in extremely desperate situations that you may request for a phone tutorial appointment with me and only after I verify your parents approval of such. In that case, before you get help from me, be ready to tell me how much you have done to help yourself. (We can communicate about this later if/when need arises). Please me (melissa.hollingsworth@hutto.txed.net) with any questions about this packet. Once you have completed an assignment, scan it or take a picture of it and it to me. I will return it with feedback. I am looking forward to a fantastic year in AP Chemistry! Have a great summer Mrs. Hollingsworth

3 The following are the Assignments included in this packet and their strict due dates. You may send your assignments ahead of time. All graded assignments will be ed back to you. You may either scan or take a picture of your work and attach it to your . Assignment # Topic Due Date 1 Scientific Notation, Significant Figures, and Density June 22 2 Formula Writing, Naming of Compounds, Balancing Equation and Types of Reactions July 13 3 Moles Grams, Molarity, and Stoichiometry July 27 4 Gas Laws August 10 5 Common Ions Quiz on 1st Day of Class Note: If you no longer have your PreAP notes, I suggest that you visit these two good websites (among the numerous ones available) for help and reference :

4 1 H Li Na K Rb Cs Fr (223) 4 Be Mg Ca Sc Ti Sr Y Zr Ba * La Hf Ra Ac Rf (261) 58 * Lanthanides Ce Actinides Th P E R I O D I C T A B L E O F T H E E L E M E N T S 5 B C Al Si V Cr Mn Fe Co Ni Cu Zn Ga Ge Nb Mo Tc (98) 44 Ru Rh Pd Ag Cd In Sn Ta W Re Os Ir Pt Au Hg Tl Pb Db (262) 106 Sg (266) 107 Bh (264) 108 Hs (277) 109 Mt (268) 110 Ds (271) 111 Rg (272) 59 Pr Nd Pm (145) 62 Sm Eu Gd Tb Dy Ho Er Pa U Np (237) 94 Pu (244) 95 Am (243) 96 Cm (247) 97 Bk (247) 98 Cf (251) 99 Es (252) 100 Fm (257) 7 N P As Sb Bi Tm Md (258) 8 O S Se Te Po (209) 70 Yb No (259) 9 F Cl Br I At (210) 71 Lu Lr (262) 2 He Ne Ar Kr Xe Rn (222) This Periodic Table is the one that is used during an AP Exam. Notice that it does not include the elements name as you are expected to get familiar with them and their correct symbols.

5 Significant Figures in Measurement and Calculations A successful chemistry student habitually labels all numbers, because the unit is important. Also of great importance is the number itself. Any number used in a calculation should contain only figures that are considered reliable; otherwise, time and effort are wasted. Figures that are considered reliable are called significant figures. Chemical calculations involve numbers representing actual measurements. In a measurement, significant figures in a number consist of: Figures (digits) definitely known + One estimated figure (digit) In class you will hear this expressed as "all of the digits known for certain plus one that is a guess." Recording Measurements When one reads an instrument (ruler, thermometer, graduate, buret, barometer, balance), he expresses the reading as one which is reasonably reliable. For example, in the accompanying illustration, note the reading marked A. This reading is definitely beyond the 7 cm mark and also beyond the 0.8 cm mark. We read the 7.8 with certainty. We further estimate that the reading is fivetenths the distance from the 7.8 mark to the 7.9 mark. So, we estimate the length as 0.05 cm more than 7.8 cm. All of these have meaning and are therefore significant. We express the reading as 7.85 cm, accurate to three significant figures. All of these figures, 7.85, can be used in calculations. In reading B we see that 9.2 cm is definitely known. We can include one estimated digit in our reading, and we estimate the next digit to be zero. Our reading is reported as 9.20 cm. It is accurate to three significant figures. Rules for Zeros If a zero represents a measured quantity, it is a significant figure. If it merely locates the decimal point, it is not a significant figure. Zero Within a Number. In reading the measurement 9.04 cm, the zero represents a measured quantity, just as 9 and 4, and is, therefore, a significant number. A zero between any of the other digits in a number is a significant figure. Zero at the Front of a Number. In reading the measurement 0.46 cm, the zero does not represent a measured quantity, but merely locates the decimal point. It is not a significant figure. Also, in the measurement 0.07 kg, the zeros are used merely to locate the decimal point and are, therefore, not significant. Zeros at the first (left) of a number are not significant figures. Zero at the End of a Number. In reading the measurement cm, the zero is an estimate and represents a measured quantity. It is therefore significant. Another way to look at this: The zero is not needed as a placeholder, and yet it was included by the person recording the measurement. It must have been recorded as a part of the measurement, making it significant. Zeros to the right of the decimal point, and at the end of the number, are significant figures. Zeros at the End of a Whole Number. Zeros at the end of a whole number may or may not be significant. If a distance is reported as 1600 feet, one assumes two sig figs. Reporting measurements in scientific notation removes all doubt, since all numbers written in scientific notation are considered significant feet 1.6 x10 3 feet Two significant figures feet 1.60 x 10 3 feet Three significant figures feet x 10 3 feet Four significant figures Sample Problem #1: Underline the significant figures in the following numbers. (a) cm answer = cm (e) ft. answer = ft. (b) in. answer = in. (f) m answer = m (c) 10 lb. answer = 10 lb. (g) 200. g answer = 200 g (d) ml answer = ml (h) 2.4 x 10 3 kg answer = 2.4 x 10 3 kg Rounding Off Numbers In reporting a numerical answer, one needs to know how to "round off" a number to include the correct number of significant figures. Even in a series of operations leading to the final answer, one must "round off" numbers. The rules are well accepted rules: 1. If the figure to be dropped is less than 5, simply eliminate it. 2. If the figure to be dropped is greater than 5, eliminate it and raise the preceding figure by If the figure is 5, followed by nonzero digits, raise the preceding figure by 1 4. If the figure is 5, not followed by nonzero digit(s), and preceded by an odd digit, raise the preceding digit by one 5. If the figure is 5, not followed by nonzero digit(s), and the preceding significant digit is even, the preceding digit remains unchanged

6 Sample Problem #2: Round off the following to three significant figures. (a) m answer = 3.48 m (c) g answer = 5.33 g (b) cm answer = 4.81 cm (d) in. answer = 8.00 in. Multiplication In multiplying two numbers, when you wish to determine the number of significant figures you should have in your answer (the product), you should inspect the numbers multiplied and find which has the least number of significant figures. This is the number of significant figures you should have in your answer (the product). Thus the answer to x 1244 would be rounded off to contain two significant figures since the factor with the lesser number of significant figures (0.024) has only two such figures. Sample Problem #3: Find the area of a rectangle 2.1 cm by 3.24 cm. Solution: Area = 2.1 cm x 3.24 cm = cm 2 We note that 2.1 contains two significant figures, while 3.24 contains three significant figures. Our product should contain no more than two significant figures. Therefore, our answer would be recorded as 6.8 cm 2 Sample Problem #4: Find the volume of a rectangular solid 10.2 cm x 8.24 cm x 1.8 cm Solution: Volume = 10.2 cm x 8.24 cm x 1.8 cm = cm 3 We observe that the factor having the least number of significant figures is 1.8 cm. It contains two significant figures. Therefore, the answer is rounded off to 150 cm 3. Division In dividing two numbers, the answer (quotient) should contain the same number of significant figures as are contained in the number (divisor or dividend) with the least number of significant figures. Thus the answer to would be rounded off to contain two significant figures. The answer to would be rounded off to contain three significant figures. Sample Problem #5: Calculate Solution: = We note that the 2.4 has fewer significant figures than the It has only two significant figures. Therefore, our answer should have no more than two significant figures and should be reported as 8.5. Addition and Subtraction In adding (or subtracting), set down the numbers, being sure to keep like decimal places under each other, and add (or subtract). Next, note which column contains the first estimated figure. This column determines the last decimal place of the answer. After the answer is obtained, it should be rounded off in this column. In other words, round to the least number of decimal places in you data. Sample Problem #6: Add g g + 4.1g Solution: g g 4.1 g Sum = g Since the number 4.1 only extends to the first decimal place, the answer must be rounded to the first decimal place, yielding the answer 86.1 g. Average Readings The average of a number of successive readings will have the same number of decimal places that are in their sum. Sample Problem #7: A graduated cylinder was weighed three times and the recorded weighings were g, g, g. Calculate the average weight. Solution: g g g g In order to find the average, the sum is divided by 3 to give an answer of Since each number extends to three decimal places, the final answer is rounded to three decimal places, yielding a final answer of g. Notice that the divisor of 3 does not effect the rounding of the final answer. This is because 3 is an exact number known to an infinite number of decimal places.

7 ASSIGNMENT 1: SCIENTIFIC NOTATION, SIG. FIGS., DENSITY Change to scientific notation. a X 10 3 = d x 10 4 = b x 10 3 = e. 870 x 10 4 = c x10 12 = f. 602 x = Determine the number of sig. figs. in the following: a = s.f. e. 670 = s.f. b = s.f. f = s.f. c. 4 x 10 2 = s.f. g x 10 2 = s.f. d = s.f. h x10 3 = s.f Perform the following calculations. Report your answer in correct number of sig.figs. and units. a m m m = b g 9.7 g = c cm cm = d cm x 2.02 cm = e x 10 2 LL gg ss s 3 =

8 Give the number of significant figures in each of the following: 402 m lbs 0.03 sec g liters ft. 5.1 x 10 4 kg 0.48 m m g 1.10 torr 760 mm Hg Multiply each of the following, observing significant figure rules: 17 m x 324 m = 1.7 mm x mm = in x in = m x 102 m = in x.090 in = cm x cm = Divide each of the following, observing significant figure rules: 23.4 m 0.50 sec = 12 miles 3.20 hours = g 1.51 moles = m sec = Add each of the following, observing significant figure rules: 3.40 m g 102. cm m 2.44 g 3.14 cm 0.5 m g 5.9 cm Subtract each of the following, observing signigicant figure rules: m g cm 1.22 m g cm Work each of the following problems, observing significant figure rules: Three determinations were made of the percentage of oxygen in mercuric oxide. The results were 7.40%, 7.43%, and 7.35%. What was the average percentage? A rectangular solid measures 13.4 cm x 11.0 cm x 2.2 cm. Calculate the volume of the solid. If the density of mercury is 13.6 g/ml, what is the mass in grams of 3426 ml of the liquid? A copper cylinder, 12.0 cm in radius, is 44.0 cm long. If the density of copper is 8.90 g/cm 3, calculate the mass in grams of the cylinder. (assume pi = 3.14)

9 4. Write at least 7 facts describing/explaining the Chemistry behind the picture on the right. 5. A g unknown substance is placed in a container with 50.0 ml water. The water level rose up to 55.2 ml. Calculate the density of the substance. 6. Draw/illustrate how the following substances will appear inside a graduated cylinder just like in #4. Liquid 1 ( 0.69 g/ml ) Solid 1 ( 0.89 g/ml ) Liquid 2 ( 1.26 g/ml) Solid 2 ( 2.04 g/ml) Liquid 3 ( water ) Liquid 4 ( 3.05 g/ml )

10 ASSIGNMENT 2: FORMULA WRITING, NAMING OF COMPOUNDS & BALANCING CHEMICAL EQUATIONS (Refer to the Periodic Table included in this packet as well as the list of polyatomic ions given in Assignment 5.) 1. Name the following ionic compounds: 2. Write ionic formulas for the following compounds: a. LiCl a. sodium acetate b. Mg(OH)2 b. tin(ii) chloride c. K3P c. calcium hydroxide d. Fe2O3 d. zinc sulfite e. FeO e. ammonium sulfate f. ZnCl2 f. manganese(ii) hypochlorite g. AgNO3 g. copper (I) nitrite h. NH4Cl h. silver cyanide i. CuCl2 i. sodium chloride j. SnCl2 j. lithium fluoride k. PbO2 k. potassium sulfide l. AlCl3 l. aluminum oxide m. PbSO4 m. nickel (II ) chlorite n. Mg3(PO3)2 n. lead (II) nitrate o. Na2CO3 0. ammonium sulfate p. NaHCO3 p. aluminum perchlorate

11 q. KCN q. iron (II) dichromate r. KMnO4 r. lead (IV) bromite s. FeC2O4 s. lead (II) periodate t. Al(ClO)3 t. magnesium thiocyanate u. FeS2O3 u. calcium thiosulfate v. Sn(CrO4)2 v. sodium bicarbonate w. Mg(HSO4)2 w. strontium hydroxide 3. Name the following covalent 4. Write the molecular formula for compounds: the following compounds: a. CO a. xenon hexafluoride b. CO2 b. tetranitrogen tetraoxidec. H2O c. boron trifluoride d. CCl4 d. carbon tetrabromide e. N2O3 e. dicarbon tetrafluoride f. SiO2 f. nitrogen tribromide g. N2O g. dinitrogen tetrasulfide h. CBr4 h. oxygen difluoride i. SO2 i. dinitrogen pentoxide j. S2Cl2 j. tetraphosphorus decoxide k. P2O7 k. sulfur hexafluoride

12 5. Translate the following word equations to a balanced chemical equations. a. iron (II) oxide + aluminum iron + aluminum oxide b. hydrochloric acid + sodium hydroxide water + sodium chloride c. calcium phosphate + sulfuric acid calcium sulfate + phosphoric acid d. calcium carbonate calcium + carbon + oxygen gas e. sodium chloride + silver nitrate sodium nitrate + silver chloride f. potassium hydroxide + sulfuric acid potassium sulfate + water 6. Identify each of the equations you balanced in #5 as reductionoxidation, precipitation or acidbase (neutralization) reactions. a. b. c. d. e. f.

13 ASSIGNMENT 3: MOLES GRAMS, MOLARITY, AND STOICHIOMETRY a. Use the Periodic Table included in this packet for the atomic masses. Do not round the atomic masses. b. Show cancellation of units and report the final answer with the correct unit and correct number of sig figs. 1. Convert the following to moles : a g C = b. 170 g O 2 = c g Cu = d g H 2 O = e g CaCO 3 = f g Ca 3 (PO 4 ) 2 = 2. Convert the following to grams: a mol H 2 = b mol Ca = c mol CO 2 = d mol AgNO 3 = e mole Al 2 (SO 4 ) 3 =

14 3. Find the concentration in molarity (M) of the following solutions: a g HCl in 2.1 L solution b g KOH in 250 ml solution c kg Ba(OH) 2 in 350 ml solution 4. Find the number of moles of solute present in the following solutions: a L of 0.25M H 2 SO 4 solution b L of 1.2M CuSO 4 solution c ml of 0.21M KNO 3 solution 5. Solve the following stoichiometric problems completely. a. Air bags in cars operate according to the reaction: 2 Na 3 N (s) 6 Na (s) + N 2(g) How many grams of nitrogen gas are produced during the decomposition of 3.25 g Na 3 N?

15 b. How many grams of lithium are needed to produce 45.0 g of lithium nitride, according to the following process? 6 Li (s) + N 2(g) 2 Li 3 N (s) c. A 24.5g sample of sodium chloride reacts with 41.3 g of fluorine gas according to the following chemical equation: 2 NaCl (s) + F 2(g) 2 NaF (s) + Cl 2(g) c.1 Which is the limiting reactant? Justify your answer with calculations. c.2 How many grams of chlorine gas are produced?

16 d. An 84.1 gram sample of phosphorus reacts with 85.0 g of oxygen according to the following equation: 4 P (s) + 5 O 2(g) 2 P 2 O 5(s) d.1 Find the limiting reactant. Justify your answer with calculations. d.2 How many grams of P 2 O 5 are produced in theory? (based on calculation) d.3 A student performed the reaction in the lab and found out that only 123 g of P 2 O 5 were produced. What then is the percent yield for P 2 O 5?

17 ASSIGNMENT 4: GAS LAWS 1. Write down what the following gas laws state and their respective equations. a. Boyle s Law : Equation : b. Charles Law : Equation : c. GayLussac s Law : Equation : d. Combined Gas Law : Equation : e. Avogadro s Law : Equation : f. Ideal Gas Law : Equation :

18 2. WORD PROBLEMS: a. Use the GUESS method (Given, Unknown, Equation, Substitution, Solution) in solving the following problems. Identify and write down the specific gas law involved before solving each problem. b. Identify the physical quantity of each Given (i.e. pressure, volume, temperature, moles) and the Unknown in the problem. c. Show cancellation of units and report the final answer with the correct unit and correct number of sig figs. Always use the Kelvin unit for temperature. Useful Information: 2.1 A L sample of gas was compressed to 10.0 ml where its pressure is torr. What was the original pressure ( in torr) of the L sample?

19 2.2 Butane gas is stored in a tank at a pressure of 10.0 atm at 22.0 C. The tank can hold a pressure of 50.0 atm before bursting. During a fire the gas is heated to C. What is the gas pressure, and will the tank contain the gas without bursting? 2.3 Calculate the volume in liters of 38.8 g of CO 2 at 725 torr and 25.0 C

20 2.4 A gas occupies ml at 655 mm Hg pressure and 30.0 C. What will its volume be at STP? 2.5 On hot days, you may have noticed that potato chip bags seem to inflate, even though they have not been opened. If I have a ml bag at a temperature of C, and I leave it in my car which has a temperature of C, what will the new volume of the bag be?

21 Assignment 5: Common Ions and Their Charges A mastery of the common ions, their formulas and their charges, is essential to success in AP Chemistry. You are expected to know all of these ions on the first day of class, when I will give you a quiz on them. You will always be allowed a periodic table, which makes indentifying the ions on the left automatic. For tips on learning these ions, see the next page. From the table: Ions to Memorize Cations Name Cations Name H + Hydrogen Ag + Silver Li + Lithium Zn 2+ Zinc Na + Sodium 2+ Hg 2 Mercury(I) K + Potassium + NH 4 Ammonium Rb + Rubidium Cs + Cesium Be 2+ Beryllium Anions Name Mg 2+ Magnesium NO 2 Nitrite Ca 2+ Calcium NO 3 Nitrate Ba 2+ Barium 2 SO 3 Sulfite Sr 2+ Strontium 2 SO 4 Sulfate Al 3+ Aluminum HSO 4 Hydrogen sulfate (bisulfate) OH Hydroxide Anions Name CN Cyanide H Hydride 3 PO 4 Phosphate F Fluoride 2 HPO 4 Hydrogen phosphate Cl Chloride H 2 PO 4 Dihydrogen phosphate Br Bromide NCS Thiocyanate I Iodide 2 CO 3 Carbonate O 2 Oxide HCO 3 Hydrogen carbonate (bicarbonate) S 2 Sulfide ClO Hypochlorite Se 2 Selenide ClO 2 Chlorite N 3 Nitride ClO 3 Chlorate P 3 Phosphide ClO 4 Perchlorate As 3 Arsenide BrO Hypobromite Type II Cations Name BrO 2 Bromite Fe 3+ Iron(III) BrO 3 Bromate Fe 2+ Iron(II) BrO 4 Perbromate Cu 2+ Copper(II) IO Hypoiodite Cu + Copper(I) IO 2 iodite Co 3+ Cobalt(III) IO 3 iodate Co 2+ Cobalt(II) IO 4 Periodate Sn 4+ Tin(IV) C 2 H 3 O 2 Acetate Sn 2+ Tin(II) MnO 4 Permanganate Pb 4+ Lead(IV) 2 Cr 2 O 7 Dichromate Pb 2+ Lead(II) 2 CrO 4 Chromate Hg 2+ Mercury(II) 2 O 2 Peroxide 2 C 2 O 4 Oxalate NH 2 Amide 3 BO 3 Borate 2 S 2 O 3 Thiosulfate

22 Tips for Learning the Ions From the Table These are ions can be organized into two groups. 1. Their place on the table suggests the charge on the ion, since the neutral atom gains or loses a predictable number of electrons in order to obtain a noble gas configuration. This was a focus in first year chemistry, so if you are unsure what this means, get help BEFORE the start of the year. a. All Group 1 Elements (alkali metals) lose one electron to form an ion with a 1+ charge b. All Group 2 Elements (alkaline earth metals) lose two electrons to form an ion with a 2+ charge c. Group 13 metals like aluminum lose three electrons to form an ion with a 3+ charge d. All Group 17 Elements (halogens) gain one electron to form an ion with a 1 charge e. All Group 16 nonmetals gain two electrons to form an ion with a 2 charge f. All Group 15 nonmetals gain three electrons to form an ion with a 3 charge Notice that cations keep their name (sodium ion, calcium ion) while anions get an ide ending (chloride ion, oxide ion). 2. Metals that can form more than one ion will have their positive charge denoted by a roman numeral in parenthesis immediately next to the name of the Polyatomic Anions Most of the work on memorization occurs with these ions, but there are a number of patterns that can greatly reduce the amount of memorizing that one must do. 1. ate anions have one more oxygen then the ite ion, but the same charge. If you memorize the ate ions, then you should be able to derive the formula for the ite ion and viceversa. a. sulfate is SO 2 4, so sulfite has the same charge but one less oxygen (SO 2 3 ) b. nitrate is NO 3, so nitrite has the same charge but one less oxygen (NO 2 ) 2. If you know that a sufate ion is SO 2 4 then to get the formula for hydrogen sulfate ion, you add a hydrogen ion to the front of the formula. Since a hydrogen ion has a 1+ charge, the net charge on the new ion is less negative by one. a. Example: 3 PO 4 2 HPO 4 H 2 PO 4 phosphate hydrogen phosphate dihydrogen phosphate 3. Learn the hypochlorite chlorite chlorate perchlorate series, and you also know the series containing iodite/iodate as well as bromite/bromate. a. The relationship between the ite and ate ion is predictable, as always. Learn one and you know the other. b. The prefix hypo means under or too little (think hypodermic, hypothermic or hypoglycemia ) i. Hypochlorite is under chlorite, meaning it has one less oxygen c. The prefix hyper means above or too much (think hyperkinetic ) i. the prefix per is derived from hyper so perchlorate (hyperchlorate) has one more oxygen than chlorate. d. Notice how this sequence increases in oxygen while retaining the same charge: ClO ClO 2 ClO 3 ClO 4 hypochlorite chlorite chlorate perchlorate