AP Chemistry Summer Assignment Mrs. Tsetsakos

Transcription

1 AP Chemistry Summer Assignment Mrs. Tsetsakos Congratulations for choosing to take AP Chemistry in September. Enclosed is the summer assignment for this class. Over the summer, you will memorize several important tables that are needed for AP Chemistry. This information was in the Regents reference tables, but must be memorized for the AP class. You are responsible for this material, as it will not be covered in class. The summer assignment is due on the first day of class in September. No late or incomplete assignments will be accepted. If you have any questions regarding this assignment, feel free to see Mrs. Tsetsakos in Room 201. Instructions 1. Memorize the tables and charts that follow. There will be a test on this the first week of school. 2. Complete the significant figures sheet. 3. Complete the compound naming sheet.

2 Polyatomic Ions Name Formula Ammonium + NH 4 Acetate C 2 H 3 O 2 Amide NH 2 Bromate BrO 3 Bromite BrO 2 Chlorate ClO 3 Chlorite ClO 2 Cyanide CN Dihydrogen phosphate H 2 PO 4 Hydrogen sulfate HSO Hydroxide OH Hypobromite BrO Hypochlorite ClO Hypoiodate IO Iodate IO 3 Iodite IO 2 Nitrate NO 3 Nitrite NO 2 Perbromate BrO 4 Perchlorate ClO 4 Periodate IO 4 Permanganate MnO 4 Thiocyanate SCN Carbonate 2 CO 3 Chromate 2 CrO 4 Dichromate 2 Cr 2 O 7 Hydrogen carbonate HCO 3 Oxalate 2 C 2 O 4 Peroxide 2 O 2 Selenate 2 SeO 4 Silicate 2 SiO 3 Sulfate 2 SO 4 Sulfite 2 SO 3 Thiosulfate 2 S 2 O 3 Phosphate 3 PO 4 Phosphite 3 PO 3 Cations H + Li + Na + K + Rb + Cs + Be 2+ Mg 2+ Ca 2+ Ba 2+ Sr 2+ Al 3+ Fe 3+ Fe 2+ Cu 2+ Cu + Co 3+ Sn 4+ Sn 2+ Pb 4+ Pb 2+ Hg Hg 2 Ag + Zn 2+ Anions H F Cl Br I O 2 S 2 Se 2 N 3 P 3 As 3 Name Hydrogen Lithium Sodium Potassium Rubidium Cesium Beryllium Magnesium Calcium Barium Strontium Aluminum Iron (III) Iron (II) Copper (II) Copper (I) Cobalt (III) Tin (IV) Tin (II) Lead (IV) Lead (II) Mercury (II) Mercury (I) Silver Zinc Name Hydride Fluoride Chloride Bromide Iodide Oxide Sulfide Selenide Nitride Phosphide Arsenide

3 Tips for Learning the Ions From the Periodic Table These are ions can be organized into two groups. 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. All Group 1 Elements (alkali metals) lose one electron to form an ion with a 1+ charge All Group 2 Elements (alkaline earth metals) lose two electrons to form an ion with a 2+ charge Group 13 metals like aluminum lose three electrons to form an ion with a 3+ charge All Group 17 Elements (halogens) gain one electron to form an ion with a 1 charge All Group 16 nonmetals gain two electrons to form an ion with a 2 charge 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). 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 cation. 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. Anions that end in ate have one more oxygen then the anions that end in ite, but the same charge. If you memorize the ate ions, then you should be able to derive the formula for the ite ion and vice versa. Sulfate is SO 4 2, so sulfite has the same charge but one less oxygen (SO 3 2 ) Nitrate is NO3, so nitrite has the same charge but one less oxygen (NO 2 ) If you know that a sulfate 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. 3 2 Example: PO 4 HPO 4 H 2 PO 4 phosphate hydrogen phosphate dihydrogen phosphate Learn the hypochlorite chlorite chlorate perchlorate series, and you also know the series containing iodite/iodate as well as bromite/bromate. The relationship between the ite and ate ion is predictable, as always. Learn one and you know the other. The prefix hypo means under or too little (think hypodermic, hypothermic or hypoglycemia ) o Hypochlorite is under chlorite, meaning it has one less oxygen The prefix hyper means above or too much (think hyperkinetic ) o The prefix per is derived from hyper so perchlorate (hyperchlorate) has one more oxygen than chlorate. Notice how this sequence increases in oxygen while retaining the same charge: ClO ClO 2 ClO 3 ClO 4 hypochlorite chlorite chlorate perchlorate

4 Rules for Determining Oxidation Number Oxidation Number A number assigned to an atom in a molecular compound or molecular ion that indicates the general distribution of electrons among the bonded atoms. 1. The oxidation number of any uncombined element is zero. 2. The oxidation number of a monatomic ion equal the charge on the ion. 3. The more electronegative element in a binary compound is assigned the number equal to the charge it would have if it were an ion. 4. The oxidation number of fluorine in a compound is always 1 5. Oxygen has an oxidation number of 2 unless it is combined with F, when it is +2, or it is in a peroxide, when it is The oxidation state of hydrogen in most of its compounds is+1 unless it combined with a metal, in which case it is In compounds, the elements of groups 1 and 2 as well as aluminum have oxidation number of +1, +2, and +3, respectively 8. The sum of the oxidation numbers of all atoms in a neutral compound is zero. 9. The sum of the oxidation number of all atoms in a polyatomic ion equals the charge of the ion. 1. Most nitrate (NO 3 ) salts are soluble. Solubility Rules 2. Most salts containing the alkali metal ions (Li +, Na +, K +, Cs +, Rb + ) and the ammonium ion (NH 4 + ) are soluble. 3. Most chloride, bromide, and iodide salts are soluble. Notable exceptions are salts containing the ions Ag +, Pb 2+, and Hg Most sulfates are soluble. Notable exceptions are BaSO 4, PbSO 4,Hg 2 SO 4, and CaSO Most hydroxide salts are only slightly soluble. The important soluble hydroxides are NaOH and KOH. The compounds Ba(OH) 2, Sr(OH) 2, and Ca(OH) Most sulfide(s 2 ), carbonate (CO 3 2 ), chromate (CrO 4 2 ), and phosphate (PO 4 3 ) salts are only slightly soluble.

5 1. Balance Charges (charges should equal zero). Rules for Making and Naming Ionic Compounds 2. Cation is always written first ( in name and in formula). If the cation has more than one charge, indicate the charge used in the name with a Roman numeral. 3. Change the ending of the anion to ide. Rules for Naming Covalent Compounds 1. The less electronegative element gets written first. 2. The first element does not need the prefix mono if there is only one atom. 3. The more electronegative element gets written second and always needs a prefix. Rules for Naming an Acid 1. When the name of the anion ends in ide, the acid name begins with the prefix hydro, the stem of the anion has the suffix ic and it is followed by the word acid. ide becomes hydro ic acid Cl is the chloride ion so HCl = hydrochloric acid 2. When the anion name ends in ite, the acid name is the stem of the anion with the suffix ous, followed by the word acid. ite becomes ous acid ClO 2 is the chlorite ion so HClO 2 = chlorous acid 3. When the anion name ends in ate, the acid name is the stem of the anion with the suffix ic, followed by the word acid. ate becomes ic acid ClO 3 is the chlorate ion so HClO 3 = chloric acid

6 Significant Figures in Measuremen nt 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 consideredd 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 plus one estimated figure (digit) 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 thee 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 five tenths 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 thesee 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 readingg B we see that 9.2 cm is definitely known. We can include one estimated digit in our reading, and we estimatee 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 nott 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 measurementt 0.46 cm, the zero does not represent a measured quantity, but merely locates the decimal point. Itt 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 includedd 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 feet Twoo significant figures feet feet Three significant figures feet feet Fourr significant figures

7 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 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 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 8.24 cm 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.

8 Sample Problem #5: Calculate Solution: = We note that thee 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 Addition and Subtraction In adding (or subtracting), set down the numbers, being sure too 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: 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 numberr 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, g. Calculate the average weight. Solution: 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 affect the rounding of the final answer. This is because 3 is an exact number, known to an infinite number of decimal places.

9 Name AP Chemistry Summer Assignment Sheet #1 Mrs. Rankin Give the number of significant figures in each of the following. 402 m lbs 0.03 sec g liters ft kg 0.48 m m g 1.10 torr 760 mm Hg Multiply each of the following, observing significant figure rules. 17 m 324 m = 1.7 mm mm = in in = m 102 m = in.090 in = cm cm = Divide each of the following, observing significant figure rules 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 significant figure rules m g cm 1.22 m g cm

10 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 11.0 cm 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)

11 Name AP Chemistry Summer Assignment Sheet #2 Mrs. Rankin Write formulas for the following substances. 1. barium sulfate 2. ammonium chloride 3. chlorine monoxide 4. silicon tetrachloride 5. magnesium fluoride 6. sodium oxide 7. sodium peroxide 8. copper (I) iodide 9. zinc sulfide 10. potassium carbonate 11. hydrobromic acid 12. perchloric acid 13. lead (II) acetate 14. sodium permanganate 15. lithium oxalate 16. potassium cyanide 17. iron (III) hydroxide 18. silicon dioxide 19. nitrogen trifluoride 20. chromium (III) oxide 21. calcium chlorate 22. sodium thiocyanate Name each of the following compounds/acids. 23. CuSO PCl Li 3 N 26. BaSO N 2 F KClO NaH 30. (NH 4 ) 2 Cr 2 O HNO Sr 3 P Mg(OH) Al 2 S P 4 O HC 2 H 3 O CaI MnO Li 2 O 40. FeI Cu 3 PO PCl NaCN 44. Cs 3 N