# Posts by Annie

Total # Posts: 835

biology
Explain how new species can originate without geographical barriers.

Calculus
Find the volume of the solid obtained by rotating the region under the graph of the function f(x) = (2)/(x+1) about the x-axis over the interval [0,3]

Calculus
Find the area of the shaded region bounded by y=7x and y=x(sqrt(22^2-x^2))

Chemistry
Carbon tetrachloride has an enthalpy of vaporization of 29.82kj/mol. If CCl4 has a normal boiling point of 350k, what is its vapor pressure at 273k? (R=8.31 J/molK)

Chemistry
What is the vapor pressure of CH4 at 1 atm and 298k?

chemistry
What is the vapor pressure of helium at 1 atm and 298 k?

math
find the critical points of h(t) = (t^2-4)^(1/3)

math
calculate the general antiderivative of f(x) = -19x^4 - 15x^3 + (20/x)

Math
limit as x approaches 9 of (8/(sqrt(x)-3)) - (48)(x-9)

chemistry
A 8.90-L container holds a mixture of two gases at 45 C. The partial pressures of gas A and gas B, respectively, are .294 atm and .860 atm. If .100 mol of a third gas is added with no change in volume or temperature, what will the total pressure become?

chemistry
if the partial pressure of the diatomic gas is .300 atm, what is the total pressure? 6 blue dots 5 orange dots 3 green dots consisting of 2 dots each (diatomic gas)

chemistry
O2 effuses at a rate that is _____ times that of Xe under the same conditions. rate 02/rate x2 = ?

chemistry
delta h= -5113.3

chemistry
for a particular isomer C8H18, the following reaction produces 5113.3 kj of heat per mole of C8H18 consumed under standard conditions c8h18(g) + 25/2 O2 (g) ---> 8co2(g) + 9h2o(g) what is the standard enthalpy of formation of this isomer of c8h18? o2= 0 co2(g)= -393.5 h2o(g...

Chemistry
Which of the following substances have a standard heat of formation of zero? O2 at 25.O degrees C and 1 atm Fe at 1200 degrees C C2H6 at standard conditions Cl2 at 2 atm

March 31-21 (Date of note)=10 days remaining. Take the 60 days-10 (days remaining in march)=50-30 (days in April)=20 days So, the maturity date of the note is May 20th.

Math
I=PRT I=40,000*.14*25/360=\$388.89 (interest) \$15,000-388.89=\$14,611.11 (amt. of partial payment left to reduce the principal) 40,000-14,611.11=\$25,388.89 (adjusted principal balance) \$25,388.89*.14*20/360=197.47 10,000-197.47=9802.53 25,388.89-9802.53=15,586.36 15,586.36*.14*...

chemistry
For the following reaction in acidic solution. Cr2O7^2- + I- ---> Cr^3+ + IO3- Give the total balanced net ionic equation.

chemistry
For the following reaction in acidic solution. Cr2O7^2- + I- ---> Cr^3+ + IO3- give the balanced half reduction reaction. Indicate the oxidizing species.

chemistry
Sorry the equation is: Cr2O7^2- + I- ---> Cr^3+ + IO3^- (dont sure the balanced equation)

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. (Use your balanced equations above.)

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 ...

physics
a flask contains helium gas at 11k. the flask is thermally isolated and the gas is allowed to escape slowly through a narrow tube until the pressure within the flask is 0.98 atm and the temperature is 4.2K. if the gas is ideal, find the initial pressure for the flask to be ...

science
what is the probability of a right handed person and a left handed person having a heterozygous child? homozygous dominant? homozygous recessive?

Probability & Statistics
Charmaine is looking at the rental car prices for Get You There Rental Car Company. The cost is based on how many miles you plan to drive the rental car. Use the list of rental prices to answer the questions 1- 5. Miles Cost 200 \$80 600 \$120 1000 \$160 1400 \$200 1800 \$320 1) ...

Probability & Statistics
Charmaine is looking at the rental car prices for Get You There Rental Car Company. The cost is based on how many miles you plan to drive the rental car. Use the list of rental prices to answer the questions 1- 5. Miles Cost 200 \$80 600 \$120 1000 \$160 1400 \$200 1800 \$320 1) ...

English
THank you SO much

English
im using APA and also if i site my sources in my essay do i use parenthesis or quotation marks? And also if i take something from a website word to word do i use quotation around it? or parenthesis?

English
its not a question its more like a four page essay. Can you tell me if i'm using a website how should i reference it? should i write the name of the website or the topic?

English

Math
A container holds 12 red marbles, 10 blue marbles, and 14 green marbles. You will randomly select two marbles without replacement. -Fill in the probabilities on each branch of the tree diagram. Use the boxes with the fraction bars already provided. -Use the tree diagram to ...

LA
D .

LA
jerry came to school incognito like superman in his clark kent glasses question; as used in the passage what does incogonito mean ? a. strength b. in a cape c. dressed formally D. disguised i pic C or D am i cerrect?

lA
yes im sorry i have misspelled that word

lA
the havasupai are ararian; they live off the summer crops they grow in the valley. .. .. what is the meaning of the word agrariam as is used in the sentence? A. farming the land to survive b . hunting south of the canyon c . herding animals such as deer d . making a livelihood...

science
Calculate the de Broglie wavelength of a 0.44 kg ball moving with a constant velocity of 26 m/s (about 60 mi/h).

Intermidete Algebra
A rectangle's length is twice its width and it's perimeter is 48m. Find the dimensions.

math
@steve Why is the base of the box 16-2x by 10-2x (where did the 2x come from?)

math
An open box is made from a rectangular piece of cardboard measuring 16 cm by 10cm. Four equal squares are to be cut from each corner and flaps folded up. Find the length of the side of the square which makes the volume of the box as large as possible. Find the largest volume

Chemistry
20 ml of 0.1 M acetic acid was mixed with 25 ml of 0.1 M Sodium Acetate. The pH was measured to be 4.43. 5 ml of 0.1 M Sodium Hydroxide was added to the buffer and the pH was measured to be 4.60. Calculate the pH of the buffer before and after the addition of NaOH.

Chemistry
1 g of acid was mixed with 120 ml of distilled water and the solution was filtered into a clean dry beaker. A 25 ml aliquot of this solution was titrated with 0.1120 M NaOH. The pH of the acid was recorded to be 4.42. Calculate the initial concentration of the weak acid and ...

Math
A gasoline tank contains 500 liters of gasoline. By the end of each day, 70% of the gasoline remains. When will there be less than 100 liters in the tank?

Math
Find the first five terms of the sequence using the recursive rule: a1 = 2/3, and An = 5a N-1

Chemistry
A 30.0-ml sample of 0.165 M propanoic acid is titrated with 0.300 M KOH. What is the pH at 5 ml of added base, at 10 ml of added base?

chemistry
Calculate whether or not a precipitate will form if 1.40 mL of 0.62 M NH3 are added to 4.4 L of 1.0 10-3 M FeSO4.

11
A ball is dropped vertically from height of 30 meters after bounces.The ball reaches a max height to 60% of height of the previous bounce. What are the terms of the sequence. What is the height to the nearest tenth of a meter of the ball after the tenth bounces?

Management Science
Riverside oil company in eastern Kentucky produces 3 different grades of gasoline. They are regular, premium, and supreme grades. Each barrel of regular grade sells for \$82 while premium grade sells for \$88 per barrel and supreme grade sells for \$89 per barrel. Petroleum ...

Physics
A roller coaster cart travelling due north at 20m/s that turns left during an interval of 4.0s without changing speed. Find the average acceleration. I understand the mathematics behind it (using pythagoras's theorem to find velocity and the formula acceleration = velocity...

math

math

math
thanks

math
The bases on a baseball diamond are 90 feet apart. How far is it from home plate to second base? Please explain

Chemistry
The pH of a 1 .00 x 10-2 M solution of cyanic acid(HOCN) is 2.77 at 25 degrees. Calculate Ka and pKa for HOCN from this result.

MATH
A ladder is 25 ft long. The ladder needs to reach to a window that is 24 ft above the ground. How far away from the building should the bottom of the ladder be placed? Please show work.

Chemistry
Thank you so much

Chemistry
Iodine is mainly found in water in the trioxide ion, I3 which is formed by the combination of molecular iodine, I2 and Iodide, I-, according to the equation: I2(aq) +I-(aq) <----> I3(aq) QUESTION: how does the system in the equilibrium seem to respond to the changes ...

Adam is 5 years younger than Eve. In 1 year, Eve will be three times as old as Adam was 4 years ago. Find their ages now.

Math
6 and8

Math
yes thanks

Math
sorry

Math
Barry is 8 years older than his sister. In 3 years, he will be twice as old as she will be then. How old is each now? Please show work! I don't understand.

American Goverment
What European country was England's primary rival in North America? In which colonies did the citizens have the most power over their own affairs? About how long after the conflict between Britain and the colonies broke into open warfare was the Declaration of Independence...

Math
solve for x in the interval [0,2π): 3csc^2(5x)=-4

math
For a fundrasier, the Best Buddies club sold t-shirts. The adult shirts were \$15 per shirt and the youth shirts were \$12 per shirt, and they made a total of \$330 on the shirts. If they sold a total of 26 shirts, how many of each did they sell? I don't understand this, so ...

Physics
A 0.03-kg bullet is fired vertically at 200m/s into a 0.15-kg baseball that is initially at rest. The bullet lodges in the baseball and, after the collision, the baseball/bullet rise to a height of 37m. (a). What was the speed of the baseball/bullet right after the collision...

Math
At a concession stand, popcorn costs \$1.10 and nachos cost \$2.35. One day, the receipts for a total of 172 popcorn and nachos were \$294.20. How many popcorns were sold. Please show work! I don't understand

Math
15 😝

Chemistry
calculate the enthalpy change for: (enthalpy of formation of aqueous sodium hydroxide is -469.60 kJ/mol. enthalpy of formation of liquid water is -285.8 kJ/mol) 2Na + 2H2O = 2 NaOH + H2

chemistry
a weather balloon partially filled w/ 33.5 L of helium @ 18 deg C & .95 atm. what volume will helium occupy @ -23 deg C w/ a pressure of 3 x 10 to the -3 atm?

chemistry
calculate the # of moles of oxygen in 2 L @ 24 deg C & 750 torr

Chemistry
# of moles of oxygen in 2 L @ 24 deg C & 750 torr?

chem hwk help!
Given the following reaction: 3 CaCl2 + 2 H3PO4 Ca3(PO4)2 + 6 HCl How many grams of H3PO4 are needed to react completely with 1.837 g of CaCl2? I don't understand at all

chemchemchem
thad do you know how to do #13?

chemchemchem
yes! thank you it worked!

In basketball you score 2 points for a field goal and 1 point for a free throw. Suppose that you have scored at least 3 points in every game this season, and have a season high score of 15 points in one game. How many field goals and free throws could you have made in any one ...

In basketball you score 2 points for a field goal and 1 point for a free throw. Suppose that you have scored at least 3 points in every game this season, and have a season high score of 15 points in one game. How many field goals and free throws could you have made in any one ...

science/evolution
what exactly is the unity of life?

science
what is the unity of life? if asked to explain two examples could it be a human and a chimp or would the two examples be DNA and RNA?

biology
what is the importance of islands in the study of evolution?

Stat
Please help with this problem, not sure calculate it. Consider the standard normal distribution and find P(-1.5 < Z < 2.35).

Math
49 bishhh

Physics
A kickoff sends a football with an initial velocity of 25 m/s at an angle of 50 degrees above the horizontal. a) find the x and y components of the velocity b) find the time the ball is in the air c) find the horizontal distance the ball travels before hitting the ground d) ...

Physics
a 254-kg crate is pushed horizontally with a force of 740 N. if the coefficient of friction is .20, calculate the acceleration of the crate

Geometry
it is not a right triangle. the easiest way i determine is if they are factors of 3,4 and 5

chemistry
The air exhaled by an average human being might have the following typical combustion, expressed in terms of partial pressures: N2 = 569torr; O2 = 116 torr; CO2 =28 torr; water vapor = 47 torr. what are the mole fractions of each?

Physics
A 50-kg satellite circles the Earth in an orbit with a period of 120 min. What minimum energy is required to change the orbit to another circular orbit with a period of 180 min? (Earth: radius = 6.4  106 m, mass = 6.0  1024 kg)

algebra
Does 6+5x=44

Chemistry
I have one more question, why is the volume of NaCl 0.05 L when we are calculating the mols and 0.1 L when we are calculating mass?

Chemistry
Thankyou so much for all the help and the explanation and your time.

Chemistry
Originally the enthalpy is negative then how does it become postive and I have followed the steps and I came up 47.36 J/g degrees C. Also I don't understand why enthalpy is q if you could please explain that, and thankyou so much.

Chemistry
yes dt is delta T and i think it is the specific heat capacity of NaCl but im not sure

Chemistry
Naoh (aq) + HCl (aq) --> NaCl (aq) + H2O (l) Using the dT determined in part 1, calculate the heat capacity of the calorimeter. Enthalpy of reaction= -58.3 kj/mol, Cs (NaCl = 3.91j/g C)density of 1 M NaCl = 1.037g/mL. dT= 12.88 degrees Celcius.50 mL of 2.00 M HCl and 50 ml ...

Chemistry
50 mL of 2.00 M HCl and 50 ml of 2.05 M NaOH were used

Chemistry
Naoh (aq) + HCl (aq) --> NaCl (aq) + H2O (l) Using the dT determined in part 1, calculate the heat capacity of the calorimeter. Enthalpy of reaction= -58.3 kj/mol, Cs (NaCl = 3.91j/g C)density of 1 M NaCl = 1.037g/mL. dT= 12.88 degrees Celcius.

Physics
Consider a stainless steel annular disk with an outer radius 68mm and inner radius7.4mm. The mass of the disk is 1349 grams. The stainless steel annular disk is allowed to rotate on a frictionless table with the rotation axis at its center. The disk has a small cylinder ...

Physics
Consider a stainless steel annular disk with an outer radius 68mm and inner radius7.4mm. The mass of the disk is 1349 grams. The stainless steel annular disk is allowed to rotate on a frictionless table with the rotation axis at its center. The disk has a small cylinder ...

Chemistry
A sample of the compound prepared in this experiment, weighing .1021g, is dissolved in HNO3 and diluted to a volume of 100mL. A 10mL aliquot of that solution is mixed with 10mL 6 M NH3. The [Cu(NH3)4 2+] in the resulting solution is 5.16x10^-3 M. How many moles of Cu were in ...

Physics
The drawing shows a jet engine suspended beneath the wing of an airplane. The weight W of the engine is 12000 N and acts as shown in the drawing. In flight the engine produces a thrust T of 54200 N that is parallel to the ground. The rotational axis in the drawing is ...

Math
How many integers bewteen 200 and 500 inclusive leave a remainder 1 when divided by 7 and a remainder 3 when divided by 4? Find the smallest positive integer that leaves a remainder 5 when divided by 7, a remainder 6 when divided by 11, and a remainder 4 when divided by 13.

Math
Which Statements of congruence are true and which are false and why? 177 _= 17 871 _= 713 1322 _= 5294 5141 _= 8353 13944 _= 8919 67 x 73 _= 1 x 3 17 x 18 x 19 x 20 _= 4! 83 (144 power) _= 15 (144 power) Their not equals signs...they are three lines on top of one another.

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