Chemistry Unit 2 Test Review Key

Chemistry Unit 2 test review Mole calculations: 1. Find the number of moles of aluminum phosphide in a 47.6 g sample. 2. How many molecules are in 44.o g of carbon dioxide? 3. How many oxygen atoms are in 180 g of acetic acid? 4. What is the mass in grams of a single molecule of calcium oxide? 5. Find the number of moles of 972.3 L of ammonia at STP. 5b. Find the mass of oxygen gas that the container could hold under the same conditions. 5c. 6. How many grams in 420 L of nitrogen dioxide at RTP? 7. How many molecules in 17,75 g of chlorine gas at RTP? 8. What is the density of fluorine gas at STP? 8b. What volume would 52 g of fluorine gas occupy at STP? 8c. What is the volume of this 52 g fluorine gas sample at RTP? 9. What is the volume of ONE MOLECULE of nitrogen gas at RTP? 10. 11. This same container will hold 3476 g of a gas made up of sulphur and oxygen atoms. Find the molecular formula of this gas SxOy (in this case, x can not = y) 8.66 g of a gas at RTP will fill a 3.0 L container. the gas and write its molecular formula. Find the molar mass of Given the data in the following table: Atmospheric pressure Temperature Density of air (determined at these conditions) Weight of Bag plus carbon dioxide gas Weight of empty bag Volume of bag FIND: a. the apparent mass of carbon dioxide b. the density of air at STP c. the mass of air that the bag could contain d. the true mass of the carbon dioxide e. the ratio of the true mass to the apparent mass 101.3 kPa 25.0 + 0.1 oC 1.25x10-3 + 0.00001 g/mL 18.97 + 0.01 g 11.49 + 0.01 g 997 + 5 mL Chem 1 Unit 2 test review p2 Buoyancy (Archimedes) and Avogadro problems: 1. A 5.00 L balloon is inflated with nitrogen trioxide (g) at 17oC and 98.5 kPa, with density of air = 1.19 g/L. The envelope mass is 8.00 g but the balance measures the inflated balloon as 9.00 g. What is the actual mass of the nitrogen trioxide (g in the balloon? 2. The same balloon is emptied then filled with carbon dioxide (g) at the same conditions. The inflated balloon now gives a mass reading of 6.97 g. How much (in grams) of carbon dioxide (g) is actually present? 3. Check the ratio of the nitrogen trioxide (g) to carbon dioxide (g) for the experimental mass data in question #2 and the theoretical mass data from the periodic table. 4. A 45 L plastic bag is inflated with methane gas at RTP. It has an envelope mass of 21.50 g. Will the bag “fly”? (or “float”). Use the density of air = 1.2 g/L. 5. A 45 L plastic bag is inflated with radon gas at RTP. It has an envelope mass of 21.50 g. Will the bag “fly”? (or “float”). Use the density of air = 1.2 g/L. Practicing names and formulas: Ion Ionic or Formula Combination Covalent Ca+2 / NO2NO4-/ B+3 Cl-/ Si+4 NH4Cl Al2S3 FeSO4 SF6 PtF6 Cl2O7 PO5 H3PO5 Name Molar Mass Calcium acetate Dinitrogen pentoxide Manganese (II) hydroxide Chromium (III) oxide Nitrogen tribromide Magnesium arsenite ALSO, List the formulas, names & molar masses of all the acids that you should know!!!! Chemistry ANSWER KEY Unit 2 test review TOOMBS Mole calculations: 1. 0.821 moles 2. 6.02 X 1023 molecules 3. 3.6 X 1024 atoms 4. 9.32 X 10-23 molecules 5. 43.4 moles 5b. 1390 g O2 5c. 80.1 g/mol which is SO3 6. 788 g 7. 1.50 X 1023 molecules 8. 1.70 g/L 8b. 31 L 8c. 34 L -23 9. 4.07 X 10 L 10. 70.7 g/mol. Closest to Chlorine gas. (Cl2) 11a. 7.48 g 11b. 1.37 g/L 11c. 1.25 g 11d. 8.73g 11e. 1.17 : 1 Buoyancy (Archimedes) and Avogadro problems: 1. 2. 3. 4. 5. mass of NO3 (g) is 6.95 g (this is the “contents” of the envelope) mass of CO2 (g) is 4.92 g (this is the “contents” of the envelope) CO2 : NO3 experimental: 4.92 : 6.95 = 0.709 : 1 periodic table (theoretical): 44.0 g/mole : 62.0 g/moles = 0.709 : Mass of CH4 (g) is 29.5 g (this is the “contents” of the envelope) Apparent mass is -3.04 g (this means that it floats/flies) 1 SIG  FIGS  note:    The  -­‐3.04  was  arrived  at,  without  reducing  the  number  of  sig  figs  in  the  calculations   (using  29.46  for  the  contents  mass).    If  you  changed  the  sig  figs  for  the  mass  of  contents  to  2  SF  (to   match  the  45L  given),  then  you  would  have  used  29g  (no  dec  places).    Then  the  apparent  mass  turns   out  to  be  -­‐3.5.  You  could  argue  that  this  should  also  be  rounded  to  -­‐4  (no  decimal  places).       SIG  FIGS  ARE  FUN! Mass of Rn (g) is 408 g (this is the “contents” of the envelope) Apparent mass is 376 g (this means that it does NOT fly/float) Practicing names and formulas: You  should  be  able  to  do  all  of  these  questions  in  the  table  on  your  own.       If  not,  please  come  and  see  me.     Acid  names:    You  should  be  able  to  change  any  “ate”  polyatomic    anion  or  any  “ite”  polyatomic    anion   to  an  acid  formula  and  then  write  the  correct  name.       You  should  also  know  how  to  add  H  to  any  anion  in  families  16  and  17,  and  then  properly  write  the   formula  and  the  name.