CHMY-361 Midterm: Montana State CHMY 361 361 14Ex2key

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turquoisegnu128

7 Mar 2019

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100 points in 8 problems on 6 pages including tables a. 5 and 7. 1. For full credit show aii worh and pal correcl units onjinal answen. Note that inforrnation that is not needed may be present in some problems. Please read: /you get a quantitative answer thd is many powers of i0from what you think it should be and cannot fnd the enor, 1nu will be reworded for pointing out apprc)timaely what you expected mtd why. 1/2n2(c) + t/2oz(d ---> no(g) at 298 k from table a. 5. Ll/t: tozso j/not t,+;: s lt + tt. = -ora\ z b 1o,o 03 35s (10 pts) 2. Calculate ars0 fornoz gas at 298kusing the data in table a. 5. t/zilz r cl. Supercooled (much below freezing point) water suddenly tqms to icg in an isolued chamber at constant pressure, and eventually comes to equilibrium. Tell whether the following are positive, zero, or negative.

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>>>>>>>>>>Only question 5 please<<<<<<<<<<<<<<<<help me find the equations for this please.

ide f Pl th th regular hexagon: Pl the unit (cm/inch) cm regular hexagon with sides To make f 5 f 10.0 cm by 8.7 cm. pape is 65.0 tee is 21.7 Th f the hexagon d th 3. (15 pts) Let's make a mini number-guessing game. Write a program that first generates a random integer between 1 and 100, and provide the player with its modulus i e the remainders when divided by 2, 5, or 13. The program then pause until the user is ready to check the answer. An example run is show below. Hint: teach yourself how to use the pause function going to gu integ bet n 1 and 100. Th ind f th integ divided by 2 is 1 is 0 The remainder of the integer divided by 5 ind f the integ divided by 13 i Th y key when you are dy t heck y is 55 Did you gue it right? The number 4. (20 pts Carbon dating is a method that determines the age of fossils based on samples' Carbon 14 radioactivity. Carbon 14, or radiocarbon, is an isotope of the element carbon that is unstable and weakly radioactive. Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes, therefore the level of C14 when they are alive is quite stable. When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay Noe where Nis the remaining radioactivity as a function of time (or age) t, No is the initial radioactivity, k is the rate of decay, and t is time s known that the ha e of C-14 is 5730 years. In other words, it takes 5730 years for its radioactivity to drop to the half of the original level, or N/N 0.5 Write a program that will calculate a sample's age based on its radioactivity. Brief steps 1) Calculate the rate constant k based on the half life of C14 2) Prompt the user for the sample's radioactivity in percentage (N/NoD 3) Calculate sample' age 4) Display the result nicely 5. (25 pts) A homeowner decides to install a round above ground swimming pool. It is du feet in diameter with an hi foot deep water level. There is a recessed portion of the pool where the water level is h2 feet deep. The rece occurs ri feet from the edge and inclines up at a 01 degree angle to the leve ground. A cross-section of the pool is illustrated in the figure below. Solve the following in terms ofthe variables stated. Be sure to follow the problem solving method described in the video labeling each Section. a) How many cubic feet of soil must be excavated from the recessed? b) How many gallons of water will be required to fill the pool? d ft dia hift ri ft Now write a MATLAB script that will prompt the user for the variables d1, hi, h2, r1 in feet, and 01 in degrees, calculate for the questions a) and b), and display proper messages on the screen. Example run: P1 t: 30 Pl hl in feet: 4 Pl h2 in f nter rl in f P1 theta in deg P1 th gl 45 To build such 762 bic feet of il ng pool, you need to exc To fill th imming po y ed 26852 gallons of Ou

1-How many grams of NaCl would be needed to prepare 150.00 L of a 1.402 M NaCl solution?

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2- first a standardized solution of sodium hydroxide (NaOH) will be quantitatively diluted to about 0.1 M but not exactly 0.1M. The molarity of the dilute NaOH will be calculated! A similar quantitative dilution was done in experiment 3 when you diluted 5.0 M HCl to 0.50M HCl using a volumetric flask and pipet.

The second part of the experiment is very similar to the last part of experiment 6 where samples of the unknown were weighed out, dissolved in water, and titrated with the dilute NaOH using phenolphthalein as the indicator to determine the percent by mass of a compound in the unknown. The compound will be different than the compound used in experiment 6. The molecular formula of the compound will be provided during the final. You must know how to weigh by difference (Preweigh, tare sample and small container to zero, transfer sample to flask, and place the small container back on balance to get mass) and titrate the sample using the buret in order to do well.

Be sure to read the instructions for the practical toward the end the CHM151L lab manual and do the practice problem on the next page.

You will have 1.5 hours to do the practical. You may only use a calculator and a pencil on the practical. There is no talking during the practical such that students cannot help each other and the TA may only help you with equipment problems.

It would be a good idea to wash any glassware you might use the lab period before the lab practical. There will also be a help session before the lab practical.

At the end of the lab final you will wash all glassware used or any dirty glassware in your locker, wash your unknown vials and remove the labels, checkin your locker and return your key, and evaluate the lab.

Please put the following statements in the correct order relating to the day of the lab practical:
1 2 3 4 5 6 Wash all your glassware and unknown vials, checkin your locker, evaluate the lab, and check your grades.
1 2 3 4 5 6 Do at least 3 good trials (weigh and titrate sample) as time allows.
1 2 3 4 5 6 Start the lab practical by diluting the NaOH solution.
1 2 3 4 5 6 Before the day of the practical clean glassware, read the practical instructions and do the practice problem in the lab manual and complete the loncapa problems for the final.
1 2 3 4 5 6 Calculate the molarity of the dilute NaOH, the percent by mass of the compound in you unknown for each trial and then the median.
1 2 3 4 5 6 Come to the help session before the lab final.

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A NaOH solution was prepared by diluting 5.00 mL of 2.205 M NaOH to a final total volume of 100.00 mL. What is the exact molarity of the dilute NaOH (use 4-5 significant figures)?

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4-For the problem above, select glassware and size from the list below to conduct the dilution.

A	Amber Bottle
B	Mohr pipet
C	Buret
D	Volumetric Flask
E	Volumetric Pipet or Pipettor
F	Graduated cylinder
G	Erlenmeyer flask
H	Beaker

A B C D E F G H <= Glassware used to transfer the 2.205 M NaOH to be diluted
A B C D E F G H <= Glassware used to measure the final volume of the diluted M NaOH.

5 10 15 20 25 50 100 250 500 1000 <= Volume of the glassware chosen to transfer the concentrated NaOH above
5 10 15 20 25 50 100 250 500 1000 <= Volume of the glassware chosen to contain the final dilute NaOH above.

Practice problems for exam 2 ______________

Useful Information:

h=6.626Ã10-34JÂ·s.; c=3.0Ã108 m/sec; E=hï® ; E= hc , ï¬ = h/mv; 1J = 1 kg-m2/s2 ï¬

mass of electron = 9.11 Ã 10-28 g, ïE= q + w ; 1 cal = 4.184 Joules Please Show all Work

1. Which of the following substances have standard heats of formation that are equal to zero by definition (circle your answers): H2(g), H(g), O3(g), H2O(s), H2O(l), Hg(l), Hg(s), Hg(g).

2. Limestone stalactites are formed in the reaction: Ca2+(aq) + HCO3-(aq) ï CaCO3(s) + CO2(g) +

H2O(l)
If one mole of CaCO3 is produced at 298 K under one atmosphere of pressure, the reaction performs 590 calories of expansion work, pushing back the atmosphere as CO2 is formed. At the same time, 9310 calories of heat are absorbed from the environment. What is ïE in Kcal/mole for CaCO3.

3. What is the minimum wavelength of light in AÌ (1 AÌ = 10-8 cm) needed to provide enough energy per quantum to rupture the chemical bond in hydrogen iodide (HI). The bond dissociation energy of HI is 71.4 Kcal/mole.

4. Sketch the shape and orientation of the following types of orbitals: s, px, dxy, dz2, dx2-y2

5. Give the values of (n) , (l) and (ml) for each orbital in the 4p subshell.

6. Write the complete electron configuration for the following: Ti 2+_____________________________________ Cr_______________________________________

N______________________________________

7. Calculate the standard enthalpy of formation ( ï Ho) for diamond from graphite [i.e. C (graphite) ï C (diamond)] given that:

C (graphite) + O2 ï CO2 (g) ( ï Ho = -393.5 KJ/mole) C (diamond)] + O2 ï CO2 (g) ( ï Ho = -395.4 KJ/mole)

If 1.0g of graphite is converted to diamond, what is the energy change? Is this an endothermic or exothermic reaction?

8. An 160 pound astronaut on his way to Mars is buzzing along at 10,000 miles per hour. (a) Express his weight in grams (one pound = 454 grams) so that you can calculate the astronautâs wavelength (1mile/hour = 44.7 cm/sec)

(b) Suppose the astronaut detects outside his spacecraft a proton (m=1.7 x 10-24 g) from a âsolar windâ moving at exactly the spacecraft velocity. What is the proton wavelength is in AÌ (1 AÌ = 10-8 cm.

9. What is the maximum number of electrons that can occupy each of the following subshells? a) 3d_________________ b) 1s____________________ c) 2p ____________________

10. Identify the element represented by the following electronic configuration.

a) [Ne] 3s2____________________

b) What is the electron configuration for the first excited state of this atom.______________

11. Determine the number of valence electrons for each element.
(a) Br___________ (b) Na _________ (c) Sn __________

12. 175 g of Fe at 15.0oC is mixed with 225 g of H2O at 95.0oC. What is the final temperature of the mixture? The specific heats of iron= 0.448 J/g oC and water = 4.184 J/g oC). (keep in mind the following: heat gained + heat lost = 0 and q=mass x heat capacity x ïT)

13. (5 pts) Calculate values of ÎHrxn for the following reactions: CS2(g) + 3O2(g) ï® CO2(g) + 2SO2(g)

The heat of formation for the following substances is given in kJ/mol:

CS2 CO2 SO2 117.4 -393.51 -296.83

14. (6 pts) Use the electron configuration of Li and Be and determine which element has the greatest second ionization energy. Defend your answer.

15. Mark beside each of the following processes either âexoâ or âendoâ according to whether you think the process will release heat or absorb heat.

a. Ca(g) ï Ca(g)+2 + 2e-
b. I(g)+1e-ï I(g)-1
c. Ca(g)+2 + S(g)-2 ï CaS(s) d. I2(g)ï 2I(g)

( ) ( ) ( ) ( )

16. (6 pts) In each of the following pairs, which of the two species is larger?
a) O-2 or Na+ b) Ti+4 or Ti+2 c) B or C d) N or N-3

17. Write down the Lewis dot structure for the following (a) N_______________ (b) Ne________________

18. THE BORN HABER CYCLE: I may have a problem on the Born Haber cycle. Please check my lecture notes to see how to set up the process and then calculate the lattice energy from the various thermodynamic quantities such as in the NaCl example below;

ï H ï¯ f NaCl = -411KJ

Na(s) ï® Na(g) ï H =108KJ
1â2 Cl2 ï® Cl(g) ï H = 122KJ Ionization Energy of Na ï H = 496 KJ Electron affinity of Cl ï H = -349KJ

CHMY-361 Midterm: Montana State CHMY 361 361 14Ex2key

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