General Questions and Answers

2 points When AH is negative and AS is positive AG will always be positive at all temperatures AG will be negative at high temperatures AG will always be negative at all temperatures AG will be negative at low temperatures

molecules of CH react with 7 molecules of O determine the number of molecules of CO that could form from each ting material 3 molecules CH x 7 molecules O x 1 molecule CO 2 molecules O Answer Bank I molecule CH 2 molecules O molecule C Incorrect Incorrect molecules CO molecules CO

is the hybridization of the N in this amic O CH3 C N CH3 H

What is the change in enthalpy for the vaporization of 3 00 L water For water AHvap 40 7 kJ mol AHfus 6 020 kJ mol O 6 78 10 kJ O 1 22 105 KJ O 6 78 109 kJ O 6 78 10 kJ

In a covalent bond between H and O which atom is the arrow representing the dipole moment of the bond pointed towards both atoms OH OF there is no dipole moment

5 Please explain how a mole and molar mass are different Use a specific example to explain the difference between a mole and molar mass 6 When 19 6 grams of NaCl reacts with excess MgS what mass of Na S will form 2 NaCl MgS MgCl Na S 7 How many moles is 1 5x1023 molecules of AgNO3 8 A sample of 7 65 1025 molecules of BaF has a mass of how many grams

Which of the phase changes illustrated here illustrates an increase in the entropy of the substance O

A mixture of hydrocarbons contains 34 2 hexane CH 4 10 5 octane CH g and 55 3 heptane C H 6 The mixture i combusted in an excess of oxygen What mass of CO is generated from the combustion of 10 1 kg of the mixture mass of CO 195 3

A sample of 57 9 g of tetraphosphorous decoxide PO reacts with 48 2 g of water to produce phosphoric acid H PO according to the following balanced equation PO10 6H 0 4H PO Determine the limiting reactant for the reaction H O OP4010 H PO Calculate the mass of H PO produced in the reaction mass of H PO 79 9445 Calculate the percent yield of H PO if 60 7 g of H PO is isolated after carrying out the reaction 174 940

5 Make a 0 50 Molar solution of substance using 100 0 mL volumetric flask Note you must adjust the amount for grams of solute for the amount of final volume of flask which is not 1 00 liter molarity moles of solute per liter This volume on the volumetric flask is To adjust the mass of solute I will need to adjust grams also by 0 50 Based on the volume of your volumetric flask of 100 mL show the new amount of grams needed for 0 50 Molar solution Molar of a liter grams CHE

7 How many moles is 1 5 1023 molecules of AgNO

For each mixture of two compounds what gas will evolve from the solution HCl aq Cu s FeS s H SO4 aq NaHCO3 aq HBr aq NH4Br aq KOH aq

a What is the Arrhenius definition of an acid b What is the Arrhenius definition of a base c What is the Bronsted Lowry definition of an acid definition of a base d What is the Bronsted Lowry

13 If 20 2 g NH4 3P reacted with yield of NH4 20 4 NH4 3P 3 PbO2 Pb3P4 6 NH4 20 4 A 0 45 gram candle is made of paraffin C25H52 A student lights the candle and covers it with a beaker trapping 2 35 g O in with the candle Eventually the flame goes out C25H52 38 O2 26 H O 25 CO

3 To produce 10 moles of ZnO s how many moles of O g must react 2 ZnS 3 0 2 ZnO 2 SO

Consider the following reaction O2 g H2 g H O g O 460 kJ mol O 220 kJ mole O 220 kJ mol O 460 kJ mol 2H2 g O2 g 2H O g AH kJ mole rxn Calculate AG for the reaction above at 298K Hint if you know what you are doing you won t use all the data and the calculation is a quick one 0 0 240 Sm J K 200 130 190

What is AS surr when 20kJ of heat is added to the system at 100K O 0 2 J K O200 J K 0 2 J K 200 J K

The gas in a balloon has a volume of 7 5 L at 100 kPa The balloon is released into the atmosphere and the gas in it expands to a volume of 11 L Assuming a constant temperature what is the pressure on the balloon at the new volume What law did you use to solve Make sure to show all work for partial credit if your answer happens to be incorrect Equations P V P V 2 P P V V P V T T T T T P V T

If a chemical reaction is spontaneous the total entropy of the chemical system an its surroundings Always increases Increases only if the reaction is exothermic Always decreases Increases only if the reaction is endothermic

Which of the following statements about the second law is CORRECT O As the number of microstates increase the entropy of a system decreases O At absolute zero perfect crystals have an absolute entropy that is negative Exothermic reactions decrease the entropy of the surroundings O The change in entropy of the universe is positive for spontaneous processes

Which of the following chemical or physical processes would you predict to have the largest NEGATIVE change in entropy OCH 202 CO2 2H O SCO2 g 4H O g O CHats 502 O 2Hg O Saltea 50 CO 4H O H O

5 Consider the following reaction Al SO 6 NaOH 3 Na SO 2 Al OH A student mixes 1 25 mol Al SO and 3 27 mol NaOH and they react A 319250 18 a What is the theoretical yield in moles of Na SO in this reaction

1 Use the equation below to answer the questions that follow Pb S04 LICI ble Pb 1 504 2 a Balance the equation above mod b Calculate the mass of lithium chloride required to react to produce 5 6 moles of lead IV chloride PbCI LISO mol bc14 mol Lic Lill mm Licl 6 94 3545 42 39 gro f 5 6 mol Pbc14 4m Lic I mul 42 39 Lick Imul cicl Pacly 949 5767 Lich c Determine the mass of lithium sulfate produced when 45 5 g of lithium chloride are reacted with an excess lead IV sulfate

13 If 20 2 g NH4 3P reacted with 20 8 g PbO2 determine the limiting reactant and the theoretical yield of NH4 20 Pb3P4 6 NH4 20 4 NH4 3P 3 PbO2

Which of the reaction below will the SMALLEST change in entropy AS O NH3 g HCl g NH4Cl s CH4 g 2O2 g CO2 g 2H O g O 2H O2 1 O2 g 2H O l O 2NH3 g 3H2 g N2 g

When 1 74 g of unknown sulphate sample was treated with BaCl solution 2 39 g of BaSO4 was obtained as product The of SO42 in the Molar mass of of BaSO4 original unknown sample is 233 39 g mol SO4 96 64 g mol A 56 8 B 70 8 60 23 64 12

7 The making of S mores is a very serious business Having the correct ratio of ingredients is very important These ratios are given in our recipe which because we are chemists we write it like a chemical equation 1G 4C 2M 1 GC M G Graham Crackers C Chocolate Pieces M Marshmallows If you have 95 Graham Crackers 362 Chocolate Pieces 180 Marshmallows a What is the limiting reactant will reduced

5 According to the reaction below nitrogen gas reacts with hydrogen gas to form ammonium NH3 N 3 H 2 NH3 a Given 3 molecules of nitrogen gas and 6 molecules of hydrogen gas make a drawing that represents the reaction container before and after the reaction In the before box circle the molecules needed to make this reaction happen once Keep circling until you are out of ingredients to make the reaction to completely occur Before b How many molecules of ammonium can be produced c which reactant is in excess Why d How many molecules of the excess reactant are there After e Assume that you have 3 moles of N and 6 moles H How many moles of Ammonium can be produced Compare your answer to 5b above

What mass in grams of precipitate will form when 303 g of nickel II nitrate reacts with excess rubidium hosphate You will need a solubility table to correctly answer this question

9 04g of manganese dioxide is reacted with 3 82g of Al according to the following equation 3MnO 4Al 4A1 3Mn 2Al O3 What mass of aluminum oxide results

Which of the following systems possess the least absolute molar entropy O 2 moles of CO2 s O 2 moles of H2 g O 1 moles of H2 g and 1 mole of O2 g O 2 moles of H O 1

for the reaction MnO 4 HCI MnCl Cl 2 H O 3 NEXT The reaction was started with 1 00 mol of MnO and 95 0 g of HCI MW 36 46 g mol Set up the table below that represents 100 yield with the given reaction conditions Ignore the water side product Before mol Change mol MnO 1 00 2 4 HCI MnCl Cl

A Complete the graphic below to show how many moles of each ion will form from the 100 dissociation of CaCl 2Cl aq H O CaCl s B Write the equation for the dissolution of each sample in water Then determine the number of moles of each ion produced as well as the total moles of ions produced a 1 mol aluminum chloride b 1 mol sodium sulfide 2 Ca aq 5 c 0 5 mol barium nitrate

20 0g of sodium is reacted with 40 0g of chlorine What mass of sodium chloride results

Vitamin D is tested for its solubility in water and benzene C6H6 and is found to be insoluble in water and soluble in benzene These solubility compound results indicate that Vitamin D is most likely a because it is in benzene O nonpolar soluble O polar soluble O ionic insoluble O None of the given answers are correct

Which graph represents the relationship between pressure and volume of a gas at constant temperature O graph I O graph II O graph III O graph IV

8 Copper reacts with silver nitrate to produce silver and copper II nitrate according to the reaction below Cu 2 AgNO3 Cu NO3 2 2 Ag a If you have 6 grams of copper 12 grams of silver nitrate how many grams of silver will you produce b What is your limiting reactant c What is your theoretical yield

20 0g of sodium chloride is reacted with 32 0g of fluorine What mass of sodium fluoride results

e Which of the following compounds will give a Self Claisen product when treated with NaOEt Ph OEt Ph H Ph OEt Ph OEt Eto O CI

Which molecule exhibits hydrogen bonding O NH3 O H S O CH4 O HCI More than one answer is correct O None of the given answers are correct Question 8

How many moles of helium are contained in 88 0 mL at STP Report the answer with a correct number of significant figures 3 93 x 10 3 mol 3 9 x 10 3 mol 3 93 mol 1 97 mol None of the given answers are correct

Arrange the following functional groups in order of increasing boiling point O A R C A B A C D OC COA OD OH C B B R OH C R C OR D R H B D C B A C D A C B D C A D B

Consider the following balanced reaction 2NaN3 s 2Na s 3N2 g How many g of N can be produced from 5 69 g NaN3 NaN3 65 01 g mol Na 22 99 g mol N 28 01 g mol Report your answer with two places past the decimal point Do not report units in your answ Type your answer

Problem J 25 00 mL of a 2 5 M solution of aqueous aluminum chloride is mixed with 75 00 mL of a 1 0 M solution of aqueous lead II nitrate The products of this reaction are aqueous aluminum nitrate and solid lead II chloride a Write a balanced chemical equation for this reaction b Determine the theoretical yield of aluminum nitrate in mols c Label the limiting reagent and the excess reagent for this reaction

A balloon that contains 0 500 L of helium at 25 C is cooled to 11 C at a constant pressure What volume does the balloon now occupy 0 477 L 1 1 L 0 525 L 0 500 L

Consider a glass of water at room temperature and assign the signs of AG AH and A S respectively for the freezing of water H O 1 H O s O O

Problem D 25 g of solid calcium carbonate decomposes into solid calcium oxide and carbon dioxide gas a Write a balanced chemical equation for this reaction

Problem I 19 00 g of aluminum chloride is dissolved in 44 00 g of water The solution that forms has density of 1 302 g mL a Calculate the m m of aluminum chloride for this solution

x Determine the AH for the third reaction O CIO g O3 g Cl g 2 O2 g AH 29 90 kJ mol 2 03 g 3 02 g AH 24 18 kJ mol Cl g 03 g CIO g O2 g A Report the answer to 4 sig figs Omit the unit label and add is the reaction is exothermic

Secondary structures are maintained by hydrogen bonding between side groups in the amino acid primary sequence O True False