General Questions and Answers

7 6 points A 0 84 gram sample of L menthol was dissolved in 11 6 mL of ethanol The sample was then placed in a 2 dm polarimeter cell The observed rotation a of the sample 2 48 Calculate the optical purity Report your answer as a WHOLE DO NOT include the symbol in your answer Cmax 51 0 wor

A polyatomic anion with a charge of 1 is formed from one atom of carbon one atom of nitrogen and one atom of sulfur What are the formal charges on the atoms in the preferred Lewis structure of this molecule Assume that carbon is the central atom FCC FCN FC

reaction Na CO3 s H3PO4 aq Na HPO4 aq CO g H O l 4 Kl aq 2 CuCl aq 2 Cul s I aq 4 KCl aq N g 3 H g 2NH3 g NH3 aq 2 O g HNO3 aq H O 1 highlighted atom is being oxidized O O reduced O O neither oxidized nor reduced O O

How many extra protons are on an object with a 8 31x1077C charge 5 19x1012 protons 7 51x1024 protons 1 33x10 25 protons 1 93x10 13 protons

The scientific method is a process that scientists use to understand the physical method in the correct order from start to finish Start formulate question from observation develop hypothesis about question test consequences of hypothesis adjust results to agree with popular opinion report outcome

The accepted AH for a reaction is 42 3 kJ mol A student has performed a lab experiment to determine the enthalpy change of he same reaction Calculate the percent error Student 1 Exp AH kJ mol Trial 1 Trial 2 Trial 3 42 9 41 7 42 0

Fiven 76 3 liters of Cl2 how many grams is this

What volume is occupied by 4 8 g O2 at 14 C and a pressure of 2 0atm

Gram Gra Using the balanced equation answer the following questions Show your work 2 Al 3 FeCO3Al2 CO3 3 3 Fe 1 How many moles of Fe are formed when 50 grams of Al react with iron II carbonate 50 g Al 1 2 How many moles of Al react to completion with 600 grams of FeCO3 600 g FeCO3 1 3 How many grams of Fe are formed when 200 g of FeCO3 react 200 g FeCO3 mol Fe mol Al g Fe

s CuSO aq FeSO4 aq Cu s redox reaction O yes reducing 0 agent oxidizing 7 agent no

3 What is the pH of a 0 320 mol L solution of benzoic acid Ka benzoic acid 6 46 x 10 5

reaction 2NH aq H SO4 aq NH4 2SO4 aq 4 HF g SiO s SiF4 g 2 H O g CO g H O g CO g H g 2H S aq O g 2S s 2H O highlighted atom is being oxidized reduced C neither oxidized nor reduced

What is the percent composition by mass of the magnesium Mg in Mg3 PO4 2 magnesium phosphate O 48 7 27 7 O 23 5 O 9 23

6 3 BL 4 Consider the following reaction CAID 2 AlBr3 3 K SO4 6 KBr Al SO4 3 to react with 440 moles of K SO 2 Answer b If you produce 0 56 moles of KBr how many moles of K SO4 will you need

1B Where C Cheese M Meat and B Buns a If you want to prote IC Che C3M B Answer Voll also need

C 16 What is the molecular shape of the PCI molecule A square planar B octahedral C square pyramidal D trigonal bipyramidal E tetrahedral

What is the approximate percent composition of phosphorus in H3PO4 65 3 31 6 29 5 98 0

READ THE PASSAGE Think about the lesson Zeno wal Can a Tortoise Be Outrun A Greek philosopher named Zeno created many paradoxes that still puzzle readers today A paradox is a altuation in which two opposing ideas both appear to be true In his famous paradox called Achilles and the Tortoise Zeno suggested that in a race a runner can never catch up to a competitor who was given a head start In Zeno s story a tortoise challenges Achilles to a race Knowing that he is far faster than the tortoise Achilles not only accepts the challenge but agrees to give the tortoise a big head start The race begins and the tortoise starts running before Achilles Eventually Achilles catches up to the place where the tortoise was when Achilles began but by then the tortoise has run a little bit farther When Achilles reaches that new spot the tortoise has run a bit farther still Achilles must always reach the spot where the tortoise was and during that time the tortoise can always run a little bit farther Achilles can never overtake the tortoise so there is no way he can win Zeno did not really believe that the tortoise would always win of course This story like all of his paradoxes challenges people to find a logical explanation for what they think The paradox is based on the false assumption that you can continue to divide distance and time by half indefinitely Zeno turns the race into an infinite series of steps that can never end when Achilles reaches where the tortoise was the tortoise has always moved ahead slightly Even though the distances decrease there are an infinite number of distances Zeno s paradox proves that this assumption is wrong because space and time are not infinitely divisible and Achilles would in fact beat the tortoise SKILL PRACTICE Read each question Fill in the bubble next to the correct answer 1 In the Achilles and the Tortoise paradox Zeno helps people improve their physical abilities proves that forward motion is impossible shows underdogs that they can win challenges the way people think 3 A paradox is something that Aproves an assumption is correct Bis true in every situation is based on emotion rather than logic seems to contradict reality 4 Achilles and the Tortoise is based around assumption about space and time determination and speed Which best represents the theme of the passage You should always follow your instinct He who runs slowly but steadily will always win People should challenge assumptions as well as explanations D Philosophy and mathematics do not mix RATEGY PRACTICE How did visualizing help you to better understand the passage men and tortoises Draces and distance

A change I g of the substance from the solid to the liquid state B raise the temperature of 1 g of the substance by 1 C C change I g of the substance from the liquid to the solid state D convert I g of a liquid to gas did to a gas 19 The specific heat of a substance is the amount of heat needed to

What is the percent composition of Cl in FeCl3

s O g CO 8 redox reaction O yes reducing agent 7 oxidizing I agent O

What is the percent composition by mass of carbon in carbon dioxide O 27 3 1 45 72 7 54 5

3 Which of the following statements describes two compounds shown below OH and a identical compounds b not identical compounds and not isomers of each other have a different molecular formula c constitutional isomers d cis trans isomers e enantiomers optical isomers OH

3 Find the amount of moles in 45 3 grams of Ca NO3 2

onsider the following reaction 3C 2M 1B C3M B Where C Cheese M Meat and B Buns a If you want to produce 50 sandwiches C M B How much Cheese will be needed

Describe the molecule cyclohexene and provide the chemical formula Cyclohexene is a linear molecule with 6 carbo atoms and 12 hydrogen atoms There is a tripl bond because it ends in ene The chemical forms is C H

EXAM use arend VERSION B 1 Consider the flasks in the diagram below containing nitrogen and neon gas respectively 230 183 P total Scot d Jeans 15 5 45 N g V1 75 L P 0 736 atm Petr n 0 675 LA4 Pads Name 1 288 0 675 1 963 est nowo 502AD Gas Law and Theory Lily Strong Ne g V 2 25 L P 0 300 atm What is the total pressure in atm after the valve is opened and the gases completely diffuse so povert P V P V yes but for each guess to conquiscab ises sur avender body 0 736 1 75 0 300 2 25 1 288 PASTY IN ON EV P total 1 963 upsea 3 1

9 In making a chalk CaCO3 FW 100 09g mol you combined 20 00 mL of 0 50M Na CO3 FW 105 99 g mol and 10 mL of 1 5 M CaCl2 FW 110 98 g mol according to the following reaction Na CO3 aq CaCl aq CaCO3 S What moles of CaCO3 will be formed from this reaction 2NaCl aq A 0 01 mol CaCO3 D 0 10 mol CaCO32 E 1 5 mol CaCO3 B 0 015 mol CaCO3 C 0 50 mol CaCO3

15 How many lone pairs of electrons are present on I in the Lewis structure of ICli D 4 A 1 B 2 E 0

What is the percent composition by mass of copper in copper II sulfate CuSO4 O 14 O 40 O 57 28

ng reaction 3 C 2M 1B Where C Cheese M Meat and B Buns C M B Answer b If you have 21 pieces of cheese how many pieces of meat will you also need

Complete each sentence based on the electron transfer process pictured below A increasing oxidized oxidizing decreasing staying the same reduced B gaining reducing losing A is Bis A is being B is being A is the B is the The oxidation state of A is The oxidation state of B is electrons electrons agent agent

0 aq OH aq SO aq H O 1 redox reaction yes reducing agent oxidizing 7

Calculate the molar mass for magnesium fluoride Round to two decimal places

units on the answer line 3 AL a student has 7 5 grams of Sulfur how many moles of sulfur will they have

SO2 O2 2SO3 toms How many atoms of oxygen are produced when 72 4 liters of SO2 combines with an excess of diatomic oxygen

Calculate the molar mass for lead IV oxide Round to two decimal places

What is the empirical formula for C4H10O2 A C H5O B CHO C C H4O D CHO E CH O

20 How much heat is required to raise the temperature of 36 1 g of temperature of 55 C The specific heat of water is 4 184 J g C A 1 98 kJ D 26 1kJ E 4 98 kJ B 33 10kJ C 41 81kJ

Calculate the molar mass for aluminum nitrate Round to two decimal places

3 A 25 00mL sample of an HCl acid solution is placed in a flask with a few drops of phenolphthalein indicator If 32 60mL of a 0 185 M NaOH solution is needed to reach the endpoint what is the concentration of the HCI solution

What is the percent composition by mass of sulfur in NH4 2SO4 ammonium sulfate O 24 32 28 O 6 7

Biphenyl C 2H o is a nonvolatile nonionizing solute that is soluble in benzene C H At 25 C the vapor pressure of pure benzene is 100 84 Torr What is the vapor pressure of a solution made from dissolving 18 3 g of biphenyl in 25 3 g of benzene

In one of the experiments of CHEM 1211 lab a student was given 2 498g of a mixture of solid copper II sulfate pentahydrate and solid salicylic acid to separate The student recovered 1 184g of salicylic acid and 1 147g of copper sulfate pentahydrate What is the mass of copper II sulfate pentahydrate the student recovered A 45 92 B 47 40 C 36 41 D 100 E 7 05

Fresh water can be squeezed out of seawater through a semipermeable membrane by using a piston to raise the pressure on the seawater side of the membrane to a value larger than the osmotic pressure To achieve a sufficient flow of fresh water the operating pressure is typically twice the osmotic pressure The membrane has to be able to withstand this pressure difference and also not become clogged too rapidly with any sediment or microorganisms that are too small to be filtered out of the seawater The density of seawater is 1030 kg m and a typical salinity is 3 5 NaCl by weight Note that 1 mol of NaCl dissociates to 2 mol of solute particles in solution Assume that the temperature is 20 C Part A What operating pressure in atm is needed by a reverse osmosis systen Express your answer in atmospheres VAXO II Submit Previous Answers Request Answer atm

What is the smallest ion in the following group Be2 Mg2 Ca Sr What information do we need to choose the smallest ion in the group Select all that apply the given ions in the problem the periodic table to obtain the number of electrons the periodic table to obtain the number of neutrons the electronegativity value of each ion the ionization energy of each ion Submit What is the smallest ion in the following group Be2 Mg2 Ca Sr2

Con Centration 4 amount of Bolute amount of solution 2 Titration of a 25 00 mL KOH base solution required 200 00 ml of 0 0050 M acetic acid What is the molarity of the KOH solution 3 A 25 00mL sample of an HCl acid solution is placed in a flask with a few drops of phenolphthalein indicator If 32 60mL of a 0 185 M NaOH solution is needed to reach the endpoint what is the concentration of the HCI solution What is the molarity of a solution prepared by dissolving 10 0g of NaOH in enough water to make 225mL of soluti 5 What is the concentration m v of a solution prepared by dissolving 10 0g of NaOH in enough water to make 25mL of solution

lowing formulas 3 H O 2 H3PO4 4 P4010 Tap in the fields to enter the answers directly OR tap on the Number Pad icon to use our built in Number Pad Hydrogen H Oxygen 0 Phosphorus P faltabbladen 7 14 C W 0 7 434 13 C W SPRESSOR DE 7

ESTIMATION BOX How Tiny Are Atoms and Molecules Problem Statement Estimate how many hydrogen atoms can fit inside a typical 355 mL soft drink can and extend that estimate to the number of protein molecules that could fit in the same can Next Step in Solution You indicated that an atom s diameter is about 100 pm express this diameter in meters m

How many mL of a 10 0 ppm TCE solution are needed to have 1 00 g of TCE a 36 00 b 5 00 1 1 2 x 10 q 185 00 y 1 00 x 105 SX C 31 00 j 1 786 k 7 143 r 444 44 Z 10 0 d 150 0 1 25 00 S 2 00 x 10 aa 1 00 ML bb 106 8 e 12 f 350 00 m 7 500 n 100 0 t 20 67 u 0 500 CC 6 00 mL 8 125 0 0 500 0 I p 15 00 V 499 5 dd 6 00 x 10 h 2 4x1 W 15 X 33 ee 6 00 x 106