# Posts by anon

Total # Posts: 2,757

**Chemistry**

In a given experiment 36.44 mL of NaOH were required for neutralize a solution of HCl 0.35 M. Calculate the moles of NaOH present to neutralize the HCl in the titration.

**physics (please help I have a test tmrw) **

How much thermal energy is released when 500g of steam at 100 degrees C condenses into liquid water and then cools to 50 degrees C? I tried to solve q=mct for q and then use that in the q=mLv formula but it didn't work. The answer is 1.3x10^6J Help would be appreciated! ...

**Math**

The box-and-whisker plot below shows the numbers of text messages received in one day by students in the seventh and eighth grades at Lincoln Middle School. Two box and whisker plots are shown above a number line. The number line is scaled from 2 to 38 by twos. The first plot ...

**Chemistry**

Arrange the following ions in terms of increasing atomic radius (arrange the increasing from left [lowest] to right [largest]): P3-, Cl-, K+, S2-

**Chemistry**

Explain why only four ionization energies are listed for Beryllium in the table listing ionization energies of elements.

**S.S.**

which event would benefit to producers rather than toy consumers?

**Maths**

Use proof by contraposition to prove that the following statement is true for all positive integers n: If n2 is a multiple of 3, then n is a multiple of 3.

**American Government**

Was this right?

**math**

i dont know

**Chemistry**

I am little confused as well. The question that I have is that for verbatim. I kind of guessed it was 7, but I didn't know if there was something that I was missing since it is a little broad.

**Chemistry**

How many different f orbitals are there?

**Chemistry**

A metal foil has a threshold frequency of 5.45 x 10^14 Hz. Which color of visible light will not eject electrons from this metal? a) blue b) indigo c) violet d) orange c=(wavelength)(v) 3.0x10^8m/s = (wavelength)(5.45 x 10^14 Hz) 550 nm -> releases green. So, I am guessing ...

**Chemistry**

I am a little confused on how you got 5E-19 J

**Chemistry**

A 32 W (1 W = 1 J/s) lamp generates violet light at a wavelength of 420 nm. How many photons of this light will the lamp generate in 2.0 s?

**Proof by contradiction**

Prove that there exists no positive real number such that: 4x^2+1/4x <1 Can I simplify this inequality in the following way: multiply both sides by 4x so we have. 4x^2+1 <4x+1 Which renders the original statement false as 4x^2+1 cant be less than 4x+1. Even further can I...

**Deduction**

Hello, Struggling to get my head around this. So we have this statement. ----------------------------------- If it rains on Monday then mark will carry an umbrella on Monday. It does not rain on Monday. You deduce: Mark does not carry an umbrella on Monday...

**Social studies **

doctors during the civil war did not have a lot to work with what would you have done to change battlefield hospitals to make them better

**Proof by contradiction **

Use proof by contradiction to show there is no real number x: 4x^2+1/4x <1

**Eigenvalues**

let the matrix A = (10 | 10 -4 | -3) Find the eigenvalues for A and for each find the corresponding eigenvector. Also express A in the form PDP^-1

**Mathematical Induction**

Use mathematical induction to prove that the following is true. 8+11+14...+(3n+5)=1/2n(3n+13), for all n in the set of natural numbers.

**Maths, dynamics**

a box slides under gravity down a flat slope 3 m long. Coefficient of sliding friction is 0.2. Show that the speed of the box at the bottom of the slope is given by sqrt(6g(sin - 0.2 cos) Thanks!

**Dynamics**

Hello, Is there a way to find the angle of inclination if given the coefficien of sliding friction? I've got 0.2 for the coefficient but I assume I can't use the old trick for find the angle give static friction I.e tan^-1 (u) = the angle.

**Mathematical Proof**

Hello everyone, Trying to get my head around deductions and the deductive step using my text book, could someone look over my work: Question: n+6 is odd if and only if 5n+1 is even. So my working, here it goes: n+6=2k+1 n=2k-5 thus 5n+1=5(2k-5)+1 =2(5k-12) so 5n+1 is even ...

**Chemistry**

You are approaching a stoplight. If the frequency of the light being emitted is approximately 520 THz, what was the wavelength of the light? What color was the light? v = c/? 520 THz --> 5.2x10^14 Hz 5.2x10^14 Hz = 3.0x10^8 m/s ? = 1.56 x 10^23 m Not sure how to get the ...

**Chemistry**

What is the energy of a photon in J emitted by the transition from the ni = 4 to the nf = 2 of a hydrogen atom?

**Math**

A college football coach wants to know if there is a correlation between his players' leg strength and the speed at which they can sprint 40 yards. He sets up the following test and records the data: Every day for a week, he counts how many times each player can leg press ...

**Social studies**

What negative impact did gold and silver mining have in the West

**Chemistry**

I know, that is why I am confused choosing an answer.

**Chemistry**

The following ions contain three oxygen atoms: A) carbonate, sulfite, and nitrite B) sulfite, nitrate, and bromate C) sulfate, hypochlorite, and carbonate D) chlorate, iodate, and phosphite I know I can eliminate A and C.

**Chem**

Calculate the standard enthalpy change for the reaction: 2C8H18(l) + 17O2(g) --> 16CO(g) + 18H2O(l) Given: 2C8H18(l) + 25O2(g) --> 16CO2(g) + 18H2O(l): ?Hº = -11,020 kJ/mol 2CO(g) + O2(g) --> 2CO2(g): ?Hº = -566.0 kJ/mol

**Chemistry**

Calculate the amount of heat necessary to raise the temperature of 12.0 g of water from 15.4ºC to 93ºC. The specific heat of water = 4.18 J/gºC. q = ms?T q = (12.0g) (4.18) (93.0 - 15.4) q = 3892.416 J ??

**Chemistry**

Potassium is a reactive element. Bromine is a reactive element. Write the complete balanced chemical equation using appropriate chemical symbols for the reaction when potassium reacts with bromine to make a solid product showing correct symbols and states of reactants and ...

**Chemistry**

The enthalpy of combustion of benzoic acid (C6H5CO2H) is –3228 kJ/mol. The burning of 1.698 g of benzoic acid in a calorimeter causes the temperature to increase by 2.865 ºC. What is the heat capacity (in kJ/ºC) of the calorimeter?

**Chemistry**

Given H2(g) + (1/2)O2(g) --> H2O, ?Hº = -286 kJ/mol, determine the standard enthalpy change for the reaction 2H2O(l) --> 2H2(g) + O2(g). Just checking... should end up with ?Hº = 572 kJ/mol right??

**Chemistry**

Given ?Hºrxn = -1670 kJ/mol for 2Al(s) + (3/2)O2(g) --> Al2O3(s), determine ?Hº for the reaction 2Al2O3(s) --> 4Al(s) + 3O2(g). I flipped Al(s) + (3/2)O2(g) --> Al2O3(s) to Al2O3(s) --> A(g) + (3/2)O2(s) and multiplied the molar values by 2. I ended up ...

**Chemistry**

Yes, I meant answer C.

**Chemistry**

Which of the following processes is endothermic? a) H2O (g) --> H2O (l) b) 3O2 (g) + 2CH3OH(g) --> 2CO2(g) + 2H2O(g) c) H2O (s) --> H2O (l) d) O2(g) + 2H2(g) --> 2H2O(g) I a guessing b, since energy has to go into the reaction for water to go from a solid to a ...

**physics**

Two small balls are attached to a rigid rod of mass 2.2 kg that is 6.0 m in length. The first ball has a mass of 2.25 kg and the second ball has a mass of 4.95 kg. (c) What is the moment of inertia of the rod when it spins around its center of mass?

**Chemistry**

So, essentially .6164 kJ/g --> kJ/mol .6165/24.31 = .0254 kJ/g

**Chemistry**

When .1625 g of Magnesium is burned in a bomb container that has a heat capacity of 3.03 kJ/ºC, the temperature increases by 1.252 ºC. How much heat (kJ/mol) is liberated during the burning of magnesium? Just want to make sure I am doing this correctly: q = ms?T q...

**Chemistry**

Calculate the enthalpy of formation if 78.5 g of carbon dioxide in the following reaction: C(s) + H2O(g) --> CO2(g) Use the following equations: a) H2O(l) --> H2(g) + (1/2)O2(g): ?°f = +285.8 kJ/mol b) C2H6(g) --> 2C(s) + 3H2(g): ?°f = +84.7 kJ/mol c) 2CO2(g...

**Chemistry**

In which of the following reactions is work done by the system to the surroundings? A) 2CH3OH(l) + 3O2(g) --> 4H2O(l) + 2CO2(g) B) S(s, rhombic) + O2(g) --> SO2(g) C) 2AgNO3(s) --> 2AgNO2(s) + O2(g) D)4Fe(s) + 3O2(g) --> 2Fe2O3(s) My guess is B because according to...

**Chemistry**

Calculate the enthalpy of formation of carbon dioxide in the following reaction: C(s) + O2(g) -> CO2(g) Use the following equations: a) H2O(l) --> H2(g) + 1/2 O2(g): ?H° = +285.8 kJ/mol b) C2H6(g) --> 2C(s) + 3H2(g): ?H° = +84.7 kJ/mol c) 2CO2(g) + 3O2(g) --&...

**Math**

Yes, this is what I thought!! Im so confused unless this is a trick question.

**Math**

Which of the following equivalences is true? x^2 ? 0 ? (x+1)^2 ? 1 x^2 ? 0 ? x^2+1 ? 1 x > 0 ? x^2 > 0 x^2 > 0 ? x^2+1 ? 1 x ? 0 ? x^2 ? 0

**Maths, dynamics**

A particle moves such that its velocity at time t is given by v =5t^5i + 4t^5j + t^3k. If its position x at time t = 0 is given by x ( 0 ) = i + 2j, what is the position of the particle at time t?

**Maths, dynamics**

A particle of mass 45 kg moves in a straight line such that the force (in Newtons) acting on it at time t (in seconds) is given by 225t^4-90 t^2-225. If at time t = 0 its velocity, v , is given by v ( 0 ) = 2, and its position x (in m) is given by x ( 0 ) = 5, what is the ...

**Social Studies**

C D A

**Chemistry**

The enthalpy of combustion of butane C4H10 is described by the reaction: C4H10(g) + (13/2) O2(g) -> 4CO2(g) + 5H2O(g) ?H°rxn = –2613 kJ/mol Given the following enthalpies of formation: ?H°f[CO2(g)] = -393.5 kJ/mol ?H°f[H2O(g)] = -241.8 kJ/mol Calculate the ...

**Chemistry**

What is the final temperature when 180.0 mL water at 101.3 C is added to 93.1 mL of water at 65.5 C?

**Chemistry**

A gas expands its volume from 4.7 L to 8.9 L at constant temperature. Answer the following: a) If the gas expands against vacuum conditions, calculate the work (in joules) done by the gas. b) Calculate the work done (in joules) by the gas if it expands against a constant ...

**World History**

Do you finish the test?

**Chemistry**

Which statement is always true if ?U sys is always negative? a) q = w b) +q>–w c) -w> +q d) +w>-q

**Chemistry**

Identify which of the following changes is exothermic. a) liquid water boils to steam b) liquid water freezes to give ice c) ice melts to give liquid water d) liquid water increases in temperature from 35 C to 45 C

**Chemistry**

what volume of oxygen is needed to react to complete reaction and to form 5cm of so3?

**Accounting Help (with answers for checking)**

Ben Guslists, vice-president of sales, has recommended adding a new product line. A market study and cost analysis show that the new line should yield the following annual results: New Sales $2,800,000.00 Cost of Sales $1,600,000.00 Operating Expenses $200,000.00 Total ...

**Algebra**

When kevin commuted to work one morning, his average speed was 45 mph. He averaged only 30 mph for the return trip because of an accident on the highway. If the total time for the round trip was 50 min determine the distance between his place of work and his home.

**Math **

the ratio of A to B is 3:8 and the ratio of B to C is 1:6 what is the ratio of A to C

**Chemistry**

Ross pours water at 6.0 C into a container with a pressure of 23. torr. He then boils the water to a temperature of 34 C. The volume changes to 18. mL and pressure to 78. torr. What was the initial volume of the water?

**Chemistry**

When a person got onto an airplane, she brought with her a half-full 1.0000 L aluminum water bottle that was closed inside the airport at standard pressure and a temperature of 26.000 C. After the plane takes off and climbs to 36,000. feet, the cabin pressure is at 0.82000 atm...

**Algebra **

For the equation -4y =8x what is the constant variation? -4 -2 1 2 Is it -2?

**Chemistry**

Which pair of reactants will not react? Au(s) with Hg^2+ (aq) Pt^2+ (aq) with Au(s) Ag(s) with Cu(s) Au(s) -> Au^3+(aq) + 3e- Hg(s) -> Hg^2+(aq) + e- Pt(s) -> Pt^2+(aq) + 2e- Cu(s) -> Cu^2+(aq) + 2e- My guess is all of them, but I am not entirely sure.

**Chemistry**

Using the following portion of the activity series for oxidation half-reactions, determine which element(s) can react with an acid to produce H2 gas. Co(s) ? Co^2+ (aq) + 2e- Ni(s) ? Ni^2+ (aq) + 2e ? Sn(s) ? Sn^2+(aq) + 2e - H2 (g) ? 2H+ (aq) + 2e ? Cu(s) ? Cu^2+ (aq) + 2e ? ...

**History**

That was really rude. I came on here because I just needed some help because my class is hard and I've read my materials. I will be giving this website a bad rating and never using it again. You could give me a link that I could read to help me understand everything but ...

**History **

Which type of rule allowed western governments to run colonies themselves? A: Direct rule B: indirect rule C: Sphere of influence D: protectorate I think it's c or d. I read my textbook but it all seems like they are under some type of government.

**ELA 6th grade**

1. B 2. C 3. B 4. B 5. A

**math**

ahh

**math**

25 + 20 + 18 + 17 = 80 27 (2) seaters = 54 spots to sit. 80 students.. 54 spots to sit. :/ Not sure how that would work out

**math**

And std 1 , 2 ,3 and 4 are the different classrooms?

**math**

two*

**math**

What's "(2) seaters"? Is it something that seats too people? I'm confused..

**math**

30% of 5,000 is 1,500. 60% of the 1,500 kids are boys. That means 40% of 1,500 kids are girls. 40% of 1,500 is 600. There are 600 girls in the town.

**art**

Yes I agree.

**Math**

Does anyone have the answers for the Penn Foster Math for Business and Finance proctored exam? 060497

**health**

I think 1. is A and 2. is B or C So yeah I agree with you.. sadly I don't know between B and C either..

**social studies**

what was major cause of problems with the sharecropping system

**Trig identies, Calculus**

Use the identities cos^2 x + sin^2 x =1 and cos2x=cos^2 x -sin^2 x to show that cos^4 x -sin^4 x = cos2x Im not sure how, I can solve my problem with half angle identities but im not sure where to start with this.

**matrix, linear transformations**

To add this is the matrix multiplication im doing to get the answer: {{4,0},{0,6}}*{{0,1},{1,0}}*{{1,2},{0,1}

**matrix, linear transformations**

Morning, Bit confused: I have been given the following: g(x,y)=(4x,6y) h(x,y)=(x+2y,y) k(x,y)=(y,x) and ive got the following matrix for each of them: g={{4,0},{0,6}} h={{1,2},{0,1}} k={{0,1},{1,0}} So ive been asked to prove the linear transformation f=k.h.g has the matrix: A...

**Math Derivatives**

Find f''(2) of function f(x)=xsin(pi/x)

**math help asap**

For the data in the table does y vary directly with x? if it does write an equation for the dorect variation. x;y 10,15 16,24 20,30 a:yes; y=1.5x b:yes;y=2x c:yes;y=x+5 d: y does not vary directly with x if you are from connections and know any other answers/know to help with ...

**Differential equations,Calculus**

Thanks Steve.

**Differential equations,Calculus**

Just to add, by doing what I described above my answer for c would be the same value as for k (i.e 3.9 or 5/4pi) so my particular solution would be. t=k(-1/r)+5/4pi

**Differential equations,Calculus**

So I have the following differential equation. The general solution I have is: t=k(-1/r)+c I now need to find the particular solution when t=0 and the radius (r) = 1cm. So k is a constant which is approx 3.9 (5/4pi) So for the particular solution im really just plugging in the...

**Algebra**

1. The perimeter of a rectangle is 78 cm. The length is 3 greater than twice its width. Find the dimensions.

**chemistry**

Confused on how to find the reactants in these two compounds Ba(OH)2 (aq) + I2Zn (aq) -> ?? Additionally, I am not really sure how to find the ionic equation for this.

**Differential equation, calculus**

Thanks, just testing out methods and got carried away!

**Differential equation, calculus **

Hiya, Dt/dr =k/r^2 Is this directly solvable or do I need to separate variables. I've got t=-k/r+c from the former and something along the lines of r^3=kt+c from the latter. Think I'm doing it all wrong. Thanks

**Biology**

What is the path that electrons take in C3 photosynthesis?

**chemistry**

Balance the following chemical reaction and determine the number of moles of HI produced when 2.33 moles of H2(g) are consumed in the following chemical reaction: ___H2(g) + __I2(g) -> ___HI (g)

**Chemistry**

Hello, I was hoping that I could get some help with calculating the mass needed to completely react with this question. In the following chemical reaction between H2 and N2 to produce NH3, what is the mass of N2 needed to completely react with 0.65 g H2 to produce 3.68 g of ...

**Differential equation **

A spherical balloon remains spherical as it is slowly inflated. The radius of the balloon r (in cm) at time t (in seconds) satisfies the differential equation. Dr/dt = k/r^2 where k is a positive constant. When the radius is 3 cm, the radius is increasing at the rate of 5/36pi...

**social studies**

The World May Never Know: Thank you so much!

**Social Studies---Please Help!**

The answer is D

**Accounting**

Cupid Co. has total assets of $600,000 and its liabilities are equal to two-thirds of its total assets. What is the amount of Cupid Co.'s Owner's Equity? Please explain how you got this answer.

**Math - limits**

Let f(t)=sint where t is the measure of the angle in degrees. Thus f is the sin function on your calculator if you select degree mode. Then: lim(t->0)(f(t)/t)= (Your answer will be a real number.)

**History**

How did the issue of states' rights influence South Carolina's decision to secede? this is a short answer, so there are no options. please help. thanks in advance :)

**History**

How did the results of the presidential election in 1860 influence South Carolina's decision to secede? there are no choices, it is a short answer. please help :)

**Math**

Which ordered pair would be plotted by starting from the origin and moving 0.25 units left and then 3 units up? A) (3, -0.25) B) (0.25, -3) C) (-0.25,-3) D) (-0.25, 3)

**Math**

How do I shift f(x)=x^2+sinx 3 to the right and 7 up?