Tuesday
July 29, 2014

Posts by Jessica


Total # Posts: 2,604

Chemistry
Calculate the change in enthalpy when 52.0 g of solid chromium at 25°C and 1 atm pressure is oxidized. (H°f for Cr2O3(s) is –1135 kJ/mol.) 4Cr(s) + 3O2(g)  2Cr2O3(s) a. –1135 kJ b. –284 kJ c. –568 kJ d. +1135 kJ e. +568 kJ

physics
A man is standing on a platform that is connected to a pulley arrangement, as the drawing shows. By pulling upward on the rope with a force the man can raise the platform and himself. The total mass of the man plus the platform is 94.7 kg. What pulling force should the man app...

Chemistry
Two 20.0-g ice cubes at –20.0 °C are placed into 295 g of water at 25.0 °C. Assuming no energy is transferred to or from the surroundings, calculate the final temperature of the water after all the ice melts. Heat capacity of H2O(s)=37.7J Heat capacity of H2O(l)=7...

Math
Which of the following classes has the largest ratio of boys to girls?

Chemistry
What is the change in enthalpy when 4.00 mol of sulfer trixoide decomposes to sulfer dioxide and oxygen gas? 2SO2 + O2 ---> 2SO3 delta H = 198kJ

Chemistry
What is the heat of combustion of ethane, C2H6, in kilojoules per mole of ethane?

Chemistry
Determine the enthalpy of the following reaction. 2M(s) + 3Cl2(g) ---> 2MCl3(s)

Chemistry
At constant volume, the heat of combustion of a particular compound is –3547.0 kJ/mol. When 1.239 g of this compound (molar mass = 196.58 g/mol) was burned in a bomb calorimeter, the temperature of the calorimeter (including its contents) rose by 8.539 °C. What is the...

Chemistry
Cr2O72-(aq) + I-(aq) -->Cr3+(aq) + IO3-(aq) What is the oxidizing species and the reducing species?

Chemistry
Using your 0.0100M oxalate solution and only the equipment and supplies listed below, describe how to prepare a 0.00025M solution of oxalate. Note, you are not allowed to add volumes with pipettes. (example, if you want 20mLs, you can not use a 10mL + 10mL addition as this add...

Chemistry
How many milliliters of 2.00 M HCl(aq) are required to react with 7.55 g of an ore containing 36.0% Zn(s) by mass?

Chemistry
Describe how to prepare a 0.0100M Solution of oxalate using solid sodium oxalate and a 500mL volumetric flask and water.

Chemistry
0.125g of sodium dichromate is to be reacted wtih 0.025M potassium iodide. How many mLs of the potassium iodide solution will be needed.

chemistry
200 ml of oxygen is collected over water at 18 degree Celsius and standard pressure, what will the volume of the dry oxygen be at STP?

Intermediate Algebra 137
Can't figure out equation x/2+x/3=3/4 can you help me step by step.

Chemistry
A 3.000gram sample of a hydrate compound containing Co, C2O4, and H2O was combusted to give 1.316g of Co3O4. What is the percentage of Cobalt in the original sample?

algebra
how do I solve this and show the work: a motorboat went upstream at 15 miles per hour and returned downstream at 20 miles per hour. How far did the boat travel one way if the round trip took 3.5 hours?

English
For homework I have to answer the following questions regarding Puerto Rican obituary by Pedro pietri but I am horrible at interpreting poems if someone can please help thank you "Puerto Rican Obituary", by Pedro Pietri: What has the American dream turned for the Pue...

Stats
The census figures show that the average income for a family in a rural region is approximately $34,860 per year. A random sample has a mean income of $33,566 per year, with a standard deviation of $1,245. At a sig. level of .0.01 is there enough evidence to reject the claim? ...

Spanish 2
Thanks!! This really helps me!!

Spanish 2
Thanks!

Spanish 2
All the verbs that have not been conjugated need to be either in preterite or imperfect form. My spanish teacher hasnt really explained it that well and I am confused on how to know whether its imperfect or preterite.Now we have a test on it tomorrow. Can someone please help m...

college agebra
(3xsquared-2x-1)(xsquared+x+5)

Trigonometry
I need help proving trigonometric identities. Most of my difficulty lies in actually factoring the equation. For example, one of the problems is (cos t - sin t)^2 + (cos t + sin t)^2 = 2. I have to prove that the left side is equal to 2. How do I do that?

rivera middle school
pablo made bread and muffins. he used 3/4 cups of flower for bread and 5/8 cups of flower for muffins. how much flower did he use in all.

Accounting
Alliant Corporation sold $100,000,000 face value 8% bonds. The bonds mature in 20 years and pay interest semiannually. The going market rate of interest on bonds of similar risk is 6%. How much will Aliant receive upon the sale of the bonds

Math/Stats
I have like 9 more of these problems, can someone please help me out so I can get started. thanx JS In a random sample of 35 tractors, the annual cost of maintenance was $4,425 and the standard deviation was $775. Construct a 90% confidence interval for this. Assume the annual...

Statistics :(
I have like 9 more of these problems, can someone please help me out so I can get started. thanx JS In a random sample of 35 tractors, the annual cost of maintenance was $4,425 and the standard deviation was $775. Construct a 90% confidence interval for this. Assume the annual...

English
I have to write an analysis of Arthur Millers involvement in the Movie and in the Play of the Crucible. How is Millers involvement in the Movie? I can not find any examples. Thanks

chemistry
why do different compounds give different retention factors (Rf values) in thin layer chromatography (TLC)

Math
What formula to use when finding patterns of sum of unit fractions #egyptian fractions

science
When 10grams of sodium chloride, NaCL,dissolves in 100grams of water, the freezing point of the water gose down to -5.9C. when 10grams of table sugar C H O, dissolves in 100grams of water, the freezing point only goes down to - 0.56C. how do yo0u account for this difference?

MATH
Let U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}. (Enter your answers as a comma-separated list. Enter EMPTY or Ø for the empty set.) {1, 4, 8} union {3, 7, 9}

math
x+y=3..(1) -(x-y=-1)..(2) 2y=4 y=2 substituting in (1) above x+y=3 x+2=3 x=3-2 x=1

calculus
yes...i copied it correctly..well i'll try again..thanks again

calculus
hey reiny--thats what i thought as well but the online homework says that answer is wrong

calculus
find the sum. use the summation capabilities of a graphing utility to verify your result. 5 Sigma (3a) k=2 ??

phy
How much heat is required to raise the body temperature of a 60.0-kg woman from 37.0° C to 38.2° C?

Chemistry
Tungsten trioxide (WO3) has a rich yellow color and is often used as a pigment in ceramics and paints. In order to test a ceramic vase for its WO3 content, a 10.10 g sample of the vase was ground and reduced with Pb(Hg) to convert any WO3 to W3 . The resulting W3 was transferr...

Chemistry
A 2.304 gram sample containing an unknown amount of arsenic trichloride and the rest inerts was dissolved into a NaHCO3 and HCl aqueous solution. To this solution was added 1.500 grams of KI and 50.00 mL of a 0.00912 M KIO3 solution. The excess I3– was titrated with 50.00...

PSY202
This branch of psychology is primarily concerned with what can be readily seen and recorded

PHYSICS! I CAN NOT GET
I have no idea. I'm pretty sure I used 2.6 instead of 2.5 on accident! OOPS

PHYSICS! I CAN NOT GET
A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.5 m separates a trough and an adjacent crest of surface waves on the lake. They count 15 crests that pass by the raft in 15 s. How fast are the waves moving? ____m/s (I got these answers and n...

Physics!! HELP
A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.5 m separates a trough and an adjacent crest of surface waves on the lake. They count 15 crests that pass by the raft in 15 s. How fast are the waves moving? _____m/s

chemistry
a salt shaker filled with 17.0g sodium chloride contain how many moles?

chemistry
an aqueous solution solution of sodium borate is sometimes used to to fire-proof wood. a. what is the molarity of 2.50 L of solution that contains 1.85 moles of sodium borate? b. what is the molarity of 45.0 L of solution that contains 6.78 kg of sodium borate? c. how manny mo...

chemistry
50 ml of a .1103M solution of formic acid is titrated with a .2511M NaOH. a) What is the pH before and NaOH is added? b) How many mL of NaOH solution must be added to reach the equivalence pt? c) what is the pH at the equivalence pt of the titration? d) If the titration is con...

chemsitry
Consider the diprotic acid H2A with K1 1*10^-3 and K2= 1*10^-9 . Find pH, [H2A], [HA], and [A2-] for a .2000M solution of H2A b)Find pH, [H2A], [HA], and [A2-] for a .200M solution of HA- c) Find pH, [H2A], [HA], and [A2-] for a .200M solution of A-

maths
4pm-12am there is an 8 hour time gap (5,6,7,8,9,10,11,12. (8 hours) 8*2=16. 14-16= (-2) so it's negative 2 degrees out.

math
5[12x+16y=1/5] 60x+80y=1--->eqn 1 4[13x+24y=1/4] 52x+96y=1 36[60x+80y=1] 30[52x+96y=1] 5[12x+16y=1/5] 60x+80y=1--->eqn 1 4[13x+24y=1/4] 52x+96y=1--->eqn 2 [60x+80y=1]36 [52x+96y=1]30 2160x+2880y=36 -1560x+2880y=30 600x=6 x=1/100 substitute the value of x in any equati...

math
6 and 1 third

math
i am less than a hundred the sum of my digits is seventeen i am an even number

Grammar
i wouldd say were

Simple Math
Please explain to me what I need to do . A cable 35 feet long runs from the top of a utility pole to a point on the ground 30 feet from the base of the pole. How tall is the utility pole ?

Math
thank you

Math
A cafeteria manager needs to know how many apples and bananas to place in a cafeteria vending machine. He conducted a survey, and all students who respended chose either an apple or banana as their preferred fruit. The survey results show that 3/4 of the students who responded...

Math
K. I'm sorry I didn't understand what way you were saying it. Good greef.

Math
Was this a smart remark? "Next time just post another question I guess :D" If so, I'm not really in the mood.. but if you meant it I do have another question........

Math
1* out of* 20

Math
You're fine. I also need help on a couple others. A survey of 500 people found that 1 lout of 20 had at least one bird as a pet. How many people who were surveyed owned at least one bird?

Math
Thanks! But how did you get that..?

Math
A tea company is making a special blend of two teas for aa customer. The ratio of Kenyan tea to Darjeeling tea in the blend is 4 to 5. How much Darjeeling tea is in 90 ounces of the blend?

Math
Collision insurance is insurance that safeguards the owner of the vehicle from damages that occur from vandalism, weather, or theft. A. True B. False

Chemistry
2.00 L of 0.800 M NaNO3 must be prepareds from a solution which 1.50 M in concentration. How many mL of the 1.50 M are required ? I am not sure weather " 2.00 L " is my V1 or V2 .

Physics
The earth's Field is Roughly equivalent to an axial centered dipole. Find the vertical rate of change of the vertical component of the earth's field in gammas/foot here at flagstaff. Given" vertical component of earth's magnetic field at flagstaff is equal to ...

Math
These are my choices ... A . 203 B. 784 C. 105 D. 392

Math
Evaluate 2y^2(x+y) when x=1 and y=7

Simple Math
Please help me with this problem . It is not hard but I need some help . In a clinical trial, a drug used to relieve pain caused side effects in 9% of the patients who took it. For a new trial, two patients were selected at random. Find the probability that neither of the pati...

life orientation
What are the two orgainizatoins that are involved in supporting noise pollution

math
A cleaner charges $0.50 per square foot to polish wood floors. A school hall has a floor area of 30 feet by 50 feet. What would be the total cost to polish the floor of the school hall? A.$80 B.$375 C.$750 D.$1,500

Chemistry
You prepare a solution from 10.0 mL of 0.100 M MOPS buffer (3-morpholinopropane-1-sulfonic acid) and 10.0 mL of 0.071 M NaOH. Next, you add 1.00 mL of 1.89 × 10-5 M lidocaine to this mixture Denoting lidocaine as L, calculate the fraction of lidocaine present in the form...

Social Studies
PLEASE ANSWER! PLEASE ANSWER! PLEASE ANSWER! 1) Identify two problems resulting from urban sprawl in the western region of the United States. If these problems are not solved, what will the outcome likely be? 2) Why do you think the Canadian government is opposed to Quebec'...

Social Studies
PLEASE ANSWER! PLEASE ANSWER! PLEASE ANSWER! Identify two problems resulting from urban sprawl in the western region of the United States. If these problems are not solved, what will the outcome likely be?

algebra
The number of red beads sheila has is four times as many as the number of green beads she has .There are 75 red and green beads.How many red beads does sheila have?

Physics
A 1.6-mole sample of an ideal gas is gently cooled at constant temperature 280 K. It contracts from initial volume 37 L to final volume V2. A total of 1.9 kJ of heat is removed from the gas during the contraction process. What is V2? Let the ideal-gas constant R = 8.314 J/(mol...

writing
Sentence 1: I am writing in reply to your advertisement in the Elkhart Sun for a sails representative. Which correction should be made to sentence 1? 1. Replace to with too 2. Replace sails with sales 3. Insert a comma after advertisement 4. Insert a comma after for 5. No corr...

algebra
the larger leg of a right triangle is 7ft longer than its samller leg. the hypotenuse is 1ft longer than the larger leg. how many feet long is the samller leg?

Prenatal Development
I'm having a hard time choosing a teratogen (anything that causes harm to a fetus), especially since all the easy ones to find ones are all taken--Radiation, Rubella, Syphilis, Hydrocodone, Heroine, Methamphetamine, Methadone, Caffeine, Nicotine, Mercury/Methylmercury, Tha...

Math--Algebra
Please help! I need this for extra credit!

Math--Algebra
What are the math problems?

physics
Susie and Sally are seated on opposing sides of a seesaw. Sally weighs 500 N and is seated a distance of 2 m from the fulcrum (point of rotation). Susie weighs 450 N and is seated a distance of 2.5 m from the fulcrum. Who is being lifted upward?

math
what is 14.876 rounded to the nearest hundredths?

Spanish 2
Thanks a lot!! :)

Spanish 2
Double Object Pronouns. Sustituya (Substitute) los complementos directos e (and) indirectos por sus respectivos pronombres. Modelo: Alberto le sirvió café a Jimena. Alberto se lo sirvió. Can you please check my anwsers for these sentences? Gracias! 1.Rica...

SPANISH 2 HELP
Thanks

SPANISH 2 HELP
Will someone check my anwsers? Thanks ¿Quién te sacó estas fotos? A. Julio me los sacó. B.Julio te las sacó. C.Julio me las sacó. ¿Quién les mandó estas flores a Uds.? A.Ceci nos los mandó. B.Ceci nos las ma...

Spanish 2
I need help picking the rightsentence form? Thanks ¿Quién te sacó estas fotos? A. Julio me los sacó. B.Julio te las sacó. C.Julio me las sacó. ¿Quién les mandó estas flores a Uds.? A.Ceci nos los mandó. B.Ce...

Math
Find the solution and round to the hundredths. 24 divided by 0.865. I got two answers I'm confused.

Chemistry
Use activity coefficients to find the concentration of hydrogen ions in a solution of 65.0 mM butanoic acid and 0.01 M NaCl. The ionization constant of butanoic acid is Ka = 1.52 × 10-5. Take the size of C3H7COO– to be 500 pm. Find [H+], pH, and alpha.

HIstory HELp!!
Please help with history? I have a project where I have to find the primary and or secondary source of today's time. The questions are 1.what is the context of the primary/secondary source that you have discovered? 2.what do you believe this reveals about society today? 3....

HISTORY
Please help with history? I have a project where I have to find the primary and or secondary source of today's time. The questions are 1.what is the context of the primary/secondary source that you have discovered? 2.what do you believe this reveals about society today? 3....

precalc
The front sprocket off a bicycle is 12 centimeters and the rear one is 5 centimeters. If the front sprocket is rotating at 40 revolutions per minute, what is the angular velocity of the little sprocket?

English
And I forgot to add, out of the 6 quizzes I only took 2. 4/5. I know I'll do good on the labs & exams but the quizzes are kinda hard. Do you think the quizzes will hurt my grade in the end? thank you!

English
Yes, I have to have c+ to pass this class.so far I have 65.6% & need 76% to pass? If I take the other 8 labs, 3 quizzes, 2 exams that are left & get C's on exam or Ds;do you think I'll get B? Thank you so much!

English
Yes, I have to have c+ to pass this class.so far I have 65.6% & need 76% to pass? If I take the other 8 labs, 3 quizzes, 2 exams that are left & get C's on exam or Ds;do you think I'll get B? Thank you so much!

English
i have a hard time calculating my grade & am in college. Please tell me the grade I have so far & will have, thank you!365 points in the course is needed. Lecture exams and quizzes are worth about 60% of the total grade &90 ≤ A 80 ≤ B < 90 70 ≤ C < 80 6...

Science
What property of water causes a water droplet to be shaped like a dome? Also can you please explain these words? Surface temperature, surface area and surface tension.

Chem
how many grams of KMnO4 should be weighed out to give 0.100 mole?

math
Nina walked 15 yards to pauls house which rule shows how many yards nina walks for every yard pauls walks

math
If the radius of a circular wave is increasing at 2 meters/sec, how fast is the area changing when the radius is 5 meters? A)62.8 square meters per second B)25.0 square meters per second C)31.4 square meters per second D)6.3 square meters per second E) None of the above

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