Circle your lab section

Transcription

1 Homework 3 Circle your lab section Name TTh 8:00 MW 11:15 MW 2:30 Directions: Work out all problems on separate sheet(s) of paper and attach this page. To receive full credit you must show all work and bo your answers. For problems containing tables, you can fill in the tables on this sheet. Please use the periodic table provided on our course website for any problems requiring the use of a periodic table. 1. Based on their position in the periodic table, determine the charge each of the following atoms will have if they become an ion. Write the charge on the line net to each number. K N Al Li Ca I Sr O 2. What is the charge of X in the following compounds? Write the charge on the line net to each number. XNO 3 Na 2 X Al 2 X 3 XCO 3 3. Name the following compounds/molecules. Write the name net to the formula. N 2 O 3 Hg 2 Cl 2 Cr(NO 3 ) 3 CuCN H 2 S Mg(OH) 2 Ag 3 PO 4 Ba(HSO 4 ) 2 CuBr SiO 2 HgCl 2 Ca(ClO 4 ) 2

2 4. Write the proper formula for the following compounds/molecules phosphorus ammonium hydroide fluorine phosphorus trichloride tin (IV) oide tin (II) peroide ammonium dichromate potassium hydrogen sulfate aluminum oide lithium sulfite ammonium hydroide lead (II) dihydrogen phosphate carbon tetrachloride silver perchlorate Mercury (I) phosphide Mercury (II) phosphide 5. Complete the following table by placing an X in the appropriate bo to indicate whether the substances listed are molecules, compounds, or neither. The first (N 2 O 3 ) is done for you as an eample. Substance Molecule Compound Neither N 2 O 3 X X H 2 S CuBr Na Al 2 O 3 Magnesium Phosphorus Fluorine Carbon tetrachloride Hydrogen Hydrogen atom Hydrogen ion Sulfate Iron Iron (II) ion

3 . Students were asked to determine the number of oygen atoms in 42.7 grams of glucose (C ). Below are three different methods used by students to solve the problem. Each method will result in the correct answer, however one method has flawed logic. Determine which method is wrong and eplain why. Method g C mole O atoms = O atoms g C mole O Method g C 3 mole O 2 2 mole O O atoms = O atoms g C mole O 2 mole O Method g C C molecules O atoms 23 = O atoms g C C molecule 7. Students were shown a sample containing 2.32 grams of bromine, and asked to calculate the number of bromine atoms present in the sample. Is one of the following methods of solving the problem better? If so, eplain why. Method g Br 2 mole Br Br 2 molecules 2 Br atoms 22 = Br g Br 2 mole Br 2 Br 2 Molecules atoms Method 2 mole Br 2.32g Br 79.90g Br Br atoms = Br atoms mole Br 8. A sample of sodium metal is determined to have a mass of 5.43 grams. How many moles of sodium are in this sample? 9. What is the mass (answer in grams) of the average calcium atom? 10. A balloon contains 4.29 grams of oygen. a. How many molecules of oygen are present in the balloon? b. How many atoms of oygen are present in the balloon? 11. A sample of aluminum oide has a mass of grams. a. What is the mass of aluminum in the sample? b. How many aluminum atoms are in the sample? 12. A sample of chlorine contains chlorine atoms. a. What is the mass of the sample? b. How many molecules of chlorine are present in the sample?

4 13. How many electrons are there in 2.45 grams of calcium? 14. How many atoms are contained within a grams sample of potassium? 15. The density of sodium chloride is 2.15 g/cm 3. How many sodium atoms are contained within cm 3 sample of sodium chloride? 1. The density of calcium carbonate is g/cm 3. How many oygen atoms are contained within cm 3 sample of calcium carbonate? 17. What is the formula mass of magnesium sulfate? 18. What is the molar mass of magnesium sulfate? 19. How many electrons are in grams of iron? 20. Calculate the mass (in grams) of the average chlorine atom. 21. A balloon is filled with grams of nitrogen. How many nitrogen molecules are present in the balloon? 22. A balloon is filled with grams of nitrogen. How many nitrogen atoms are present in the balloon? 23. How many atoms of sulfur are required to make grams of aluminum sulfide? 24. The human body is composed of many types of atoms (O, C, H, N, Ca, P, etc ). If you were to calculate the weighted average for an atom in the human body it would be 14.5 atomic mass units. The average human cell has a mass of kg. Calculate the number of atoms within the human cell assuming the cell has the same composition as the human body on average. 25. Popcorn kernels were used in lab to give a perspective on just how large Avogadro s number is. Come up with your own eample (including calculations) to show the magnitude of this number. 2. Calculate the mass of carbon in grams of C H. 27. Calculate the mass of hydrogen in grams of C H. 28. The mass percent of a given element in a compound is defined by the following equation. Determine the mass percent of carbon in C H. mass percent = mass of element mass of compound 100% 29. A gram sample of a compound composed of iron and sulfur was analyzed and determined to contain 3.52% iron and 3.48% sulfur. What is the empirical formula of this compound?

5 30. Complete the following table. You must show work for all answers. Wavelength (nm) Wavelength (m) Frequency (Hz) What region of the electromagnetic spectrum corresponds to a wavelength of nm? 32. Calculate the frequency of light described by the wave shown below. Assume the wave is traveling at he speed of light. 5. nm 33. Using the diagram below measure the wavelength and amplitude in centimeters. Use a ruler that will allow for you to report the length to two decimal places. Wavelength (cm) Amplitude (cm)