Sunday

April 20, 2014

April 20, 2014

Total # Posts: 124

**chemistry**

calculate the volume of concetrated nitric acid (68%) that is neede to prepare stock solution 0.25M in 1000mL volumetric flask.(dnitric acid=1.513g/cm3)

**math 4 grade**

the 18,000

**english LIT **

HELP Please help me what this quotes mean then I have to write WHAT I think about it. i already get eight of them but idont get rest of them. 1) Or I will become engulfed with all I did or I did not do, with what should have been and what cannot be helped 2) You do not guess h...

**Please HELP **

Please help me what this quotes mean then I have to write WHAT I think about it. i already get eight of them but idont get rest of them. 1) Or I will become engulfed with all I did or I did not do, with what should have been and what cannot be helped 2) You do not guess how ne...

**english lit**

Please help me what this quotes mean then I have to write WHAT I think about it. i already get eight of them but idont get rest of them. 1) Or I will become engulfed with all I did or I did not do, with what should have been and what cannot be helped 2) You do not guess how ne...

**physics**

can you give the solution?

**physics**

A 0.33- kg pendulum bob is attached to a string 1.2 m long and hangs vertically as shown in Figure 1. What is the change in the pendulum bob’s gravitational potential energy as it swings from the lowest point of the pendulum to a point that is 35 degree to the vertical?

**finance, please help**

1. Calculate the present value of an investment given the following information: (a) Years—20, (b) Rate—10%, and (c) Future Value—$20,000. 2. Calculate the future value of an investment given the following information: (a) Years—10, (b) Rate—5%, and (c...

**Reasearch or Term paper ideas**

I am doing my bachelors in forensic science semester two... I would like to know any common topics one may write over 30pages for a research or term paper in regard with forensic science. i tried body language and anti-social behaviour, though this topic does not really suit m...

**statistics, please help**

Thaarugo, inc., produces a GPS device that is becoming popular in parts of scandinavia, When thaarugo produces one of these, a printed circuit board (PCB) is used, and it is populated with several electronic components, Thaarugo determines that it needs about 16,000 of this ty...

**Chemistry**

The explosive residue contains carbon, hydrogen and nitrogen where the percentage of nitrogen is high, calculate it from 0.5g of residue which eliminates ammonia gas on reaction with sodium hydroxide, and absorb by 50mL of Nby10 H2SO4. Unused acid is neutralized/titrated with ...

**D.E**

A particle moves on the x-axis with an acceleration, 246msta. Find the position and velocity of the particle at 3t, if the particle is at origin and has a velocity of 10ms when 0t by using either the method of und...

**diff eqn.**

y(t) = -0.2451 cos 4t + 0.9804 sin 4t + e^(-3t ) (A cos〖t+B〗 sin〖t)〗 y'(t) = ?

**chemistry - hess's law (check + help)**

31. Carbon monoxide reacts with hydrogen gas to produce a mixture of methane, carbon dioxide, and water. (This mixture is known as substitute natural gas.) 4CO(g) + 8H2(g) → 3CH4(g) + CO2(g) + 2H2O(_) Use the following thermochemical equations to determine the enthalpy c...

**chemistry - enthalpy change and finiding volume of**

29. Consider the following chemical equations and their enthalpy changes. CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) ΔH = −8.0 × 102 kJ CaO(s) + H2O(_) → Ca(OH)2(aq) ΔH = −65 kJ What volume of methane, at 20°C and 100 kPa, would have to be c...

**Chemistry - enthalpy and rate constant (check)**

22. The rate of a chemical reaction is dependent on its ΔH. Do you agree or disagree with this statement? Briefly justify your answer. I agree with the above statement, enthalpy is defined as the internal energy of the reactants and products therefore the chemical reactio...

**Chemistry - enthalpy of combustion(help!!!)**

i tried using it for CH4, below is my working am i correct? cause i researched a website(cannot post link) and it uses enthalpy of formation!!! i am using the molar enthalpy of formation equation: (ndeltaHf products) - (ndeltaHf reactants) CH4 + 2O2 ↔ 2H2O + CO2 deltaCOM...

**Chemistry - enthalpy of combustion(help!!!)**

i need help with the below question, i have tried answering it, but do not know where to go after the equations, please start me off on how to find the enthalpy of combustion of at least one.... Consider methane, CH4, and hydrogen, H2, as possible fuel sources. (a) Write the c...

**chemistry - ionization energy(check + help)**

I need help understanding by boron does not follow the ionization trend across the period is lower than the first two elements in the same period, where as it should be higher. has it got to do with the p block having an electron, which makes it easier to remove the electron h...

**chemistry - electron configuration(check)**

is the below the correct electronic configuration for arsenic? Arsenic:[Ar]4s23d104p3

**chemistry - structure and properties (help)**

I have a revision question which i do not understand please help me out: 45. Explain the following observations: motor oil pours from a can more slowly than water; however, in a jar, the meniscus of motor oil is flatter than the meniscus of water. The answer sheet talks about ...

**Chemistry - oxidation numbers**

How do you use a Lewis Structure to find the oxidation state of an element. I have this question using the oxidation rule i got +2, however how do i use it with Lewis structure. QUESTION Use the Lewis structure of a thiosulfate ion to find the oxidation number of each sulfur a...

**Chemistry - Ksp **

i did an experiment where we titrated HCl on calcium hydroxide, and now i am confused with the calculations, i do not know if i am correct, so please help me out... Trial One volume of HCl used - 11.20mL concentration of HCl - 0.04mol/L so to get moles of HCl i used M= CV is t...

**chemistry - combustion**

Write the chemical equation for the complete combustion of each fuel. Then find the enthalpy of combustion, ΔHcomb, of each fuel. Express your answers in kJ/mol and kJ/g. Assume that water vapour, rather than liquid water, is formed in both reactions. CH4 + 2O2 ↔ 2H...

**chemistry - heat absorption (help)**

When a vehicle is parked in the sunlight on a hot summer day, the temperature inside can approach 55°C. One company has patented a non-CFC propelled aerosol that can be sprayed inside a vehicle to reduce the temperature to 25°C within seconds. The spray contains a mixt...

**Chemistry - enthalpy reivison(help)**

58. When a vehicle is parked in the sunlight on a hot summer day, the temperature inside can approach 55°C. One company has patented a non-CFC propelled aerosol that can be sprayed inside a vehicle to reduce the temperature to 25°C within seconds. The spray contains a ...

**calculus**

i still dont get it the answer for question 1, c and d..can u give me the answer please..

**Chemistry - NO2 Calculation**

(a) Calculate [NO2] at each time interval, based on [O2]. Assume initial [NO2] = 0.0 mol/L. how do i calculate NO2 at this time intercal so when t= 600s O2 in mol/l = 0.0021

**Chemistry - NO2 Calculation**

(a) Calculate [NO2] at each time interval, based on [O2]. Assume initial [NO2] = 0.0 mol/L. how do i calculate NO2 at this time intercal so when t= 600s O2 in mol/l = 0.0021

**chemistry - decomposition of water(help)**

Thank you, helped, the equations do balance out, and there are more than one ways to solve this either by multiplying the first equation by 2 and then manipulating further as well as just canceling out and adding all by hess's law.

**chemistry - decomposition of water(help)**

Hydrogen is a very appealing fuel, in part because burning it produces only non-polluting water. One of the challenges that researchers face in making hydrogen fuel a reality is how to produce hydrogen economically. Researchers are investigating methods of producing hydrogen i...

**chemistry - decomposition of water(help)**

Hydrogen is a very appealing fuel, in part because burning it produces only non-polluting water. One of the challenges that researchers face in making hydrogen fuel a reality is how to produce hydrogen economically. Researchers are investigating methods of producing hydrogen i...

**biology - glycolysis +atp (help)**

9. The total amount of energy released from the chemical bonds of glucose is 2870 kJ/mol, after the initial investment of 2 ATP. The total energy that can be harvested to form ATP molecules is about 1200 kJ/mol. a. After the initial investment of 2 ATP, 38 ATP are produced. Ho...

**Biology - gylcolysis history (help+check)**

The process of glycolysis is thought to have emerged very early in the origins of life. What evidence to support this theory can you find in the material presented in this section? Be prepared to defend your ideas. Ans: is this question indirectly related to cell theory, the o...

**chemistry - human calorimeter**

From experience, you know that you produce significantly more heat when you are exercising than when you are resting. Scientists can study the heat that is produced by human metabolism reactions using a ‘human calorimeter.’ Based on what you know about calorimetry, h...

**Chemistry - physical, chemical and nuclear process**

A healthy human body maintains a temperature of about 37.00C. Explain how physical, chemical and nuclear processes all contribute, directly or indirectly, to keeping the human body at a constant temperature.

**Chemistry - physical, chemical and nuclear process**

A healthy human body maintains a temperature of about 37.00C. Explain how physical, chemical and nuclear processes all contribute, directly or indirectly, to keeping the human body at a constant temperature.

**Chemistry - Enthalpy change and stoichiometry **

N2 + O2 = 2NO enthalpy change = +180.6kJ c) what is the enthalpy change for the formation of one mole of nitrogen monoxide? d) What is the enthalpy change for the reaction of 1.000 * 10^2g of nitrogen with sufficient oxygen? I do not understand how to calculate the above, can ...

**Chemistry - matter and energy.**

Distinguish between the view of matter and energy in microscopic world and view matter and energy in the quantum mechanical world. I do not understand this question, i tried googling it, but hardly got something to give me an idea about. Please help.

**Chemistry -Flame colors (check+help)**

What are the characteristic flame color for sodium, potassium, barium, copper, strontium, and calcium? Explain why? Ans: i know the flame colours, but for the explain why, could the below be a possible answer? The characteristic flame color is due to the shift in the energy le...

**Chemistry - Lewis Structures (check + help)**

I am asked to draw lewis strcutures of the following molecules and ions SF6, BrF5, XeF4, PF5 and IF4-. I have to follow a specific format to draw them, below is an example of SF6, where am i going wrong in the table, since i am not getting six bonds, nor am i successful with t...

**Chemisdtry - Lewis Structures (check + help)**

Draw Lewis structures for each of the following ion: CO3 (2-) I tried this method below, i do not know where am i going wrong, please help me understand this concept for ions. Valence Electrons 4e- + 18e- = 22e- Noble gas Config 8e- + 24e- = 32e- Total 32e- 22e- = 10e- Covalen...

**Chemistry - Periodic Table+IE(check+help)**

The following data lists the ionization energies for a given atom: IE1 = 738Kj/mol; IE2 = 1451Kj/mol; IE3 = 7733Kj/mol. Predict the valence electron configuration for this atom, and explain your reasoning. i do not understand this question but i will give it a try, please chec...

**Chemistry - Periodic Table+Cations(check+help)**

On which side of the periodic table would you find an element whose atom is likely to form a cation? Which atom property is related to this question? Ans: is it the right side of the periodic table that you would find the elements whose atom are likely to form a cation, since ...

**Chemistry - Periodic Table+IE(check+help)**

The following data lists the ionization energies for a given atom: IE1 = 738Kj/mol; IE2 = 1451Kj/mol; IE3 = 7733Kj/mol. Predict the valence electron configuration for this atom, and explain your reasoning. i do not understand this question but i will give it a try, please chec...

**Chemistry - Periodic Table+Cations(check+help)**

On which side of the periodic table would you find an element whose atom is likely to form a cation? Which atom property is related to this question? Ans: is it the right side of the periodic table that you would find the elements whose atom are likely to form a cation, since ...

**english + law - creating sentences**

Use Amending formula, rule of law and civil law individually in sentences. Please help me form sentences, i cannot crack my brain around these three.

**density and density error (check calculations)**

Calculate the density of earth and its density error d=m/v where m = 6.00*10^24kg and v = (4/3)(pi)(6359000)^3 = 1.07709...*10^21 m^3 therefore d=6.00*10^24/1.07709...*10^21 m^3 d = 5570.5254...kg/m^3 using the sig fig rule, in division and multiplication take the least decima...

**chemistry - density and error (check)**

Calculate the density of earth and the density error. i got the answer 5.57*10^3k +/- 9.60 *10^7kg/m is that the correct answer? please help

**Chemistry - Unit Analysis**

The molar mass of cupric chloride is 134.45g/mol. What is the mass, in grams, of 8.19*10^-3 mol of this compound?

**chemistry 11 grade **

A piece of iron wire weighs 2.225g. It is dissolved in acid, which oxidizes the iron to iron(II), and made up to 250 mL. A 25mL sample required 31.0 mL of a 0.0185mol/L solution of potassium dichromate. Calculate the percentage of iron in the wire.

**AP World History**

I need some continuities and changes in economy in the islamic world from 600-1750 AD, please help? Just a list would be fine with me thank you!!! :D

**physics - speed of electron in magnetic field **

A beam of electron is accelerated by a potential difference of 2.5okV. The electrons are then allowed to pass into a magnetic field of strength 10.0mT. As the electrons enter the field, the direction of the velocity is at right angles to the direction of the magnetic field. Al...

**Physics - check this work for horizontal displacem**

A 1.5kg melon is placed on top of the post. A girl lying on the ground fires a 500g arrow at ground level with velocity of 20m/s, 60deg above the horizontal, and hits the melon when the arrow is at its highest point. The melon, with the arrow embedded, falls to the ground. Fin...

**Physics - electric field intesity (check +help)**

Points A and B are 13.0 apart. A charge of +8.0mu is placed at A and another charge at +5.0mu is placed at B. Point P i located 5.0cm from A and 12.0cm from B. What is the magnitude and direction of the electric field intensity at P? Ans: i got the magnitude as 2.9*10^, howeve...

**Physics - conservative and non conservative (check**

If a sled reaches the base of the hill with a speed of 15.6m/s, how much work was done by the snow on the sled between points x and y, where x is 3m above the ground with a velocity of 14.30m/s and y is toughing the ground. the sled and the rider are 70kg Ans: i tried the form...

**Physics - bungee jumping**

In a head dip bungee jump from abridge over a river, the bungee cord is fastened to the jumpers ankles. The jumper then steps off and falls towards the river until the cord becomes taut. At that point, the cord begins to slow the jumper's descent, until his head just touch...

**Physics - elastic collision**

I tried solving this by separating the components into the vertical and horizontal, before and after collision. but i only obtain velocity and the deg, however the questions asks for the distance...

**Physics - elastic collision**

A student flings a 23g ball of putty at a 225g cart sitting on a slanted air track that is 1.5m long. The track is slanted at an angle of 25deg with the horizontal. If the putty is traveling at 4.2m/s when it hits the cart, will the cart reach the end of the track before it st...

**Physics - Collision in teo dimensions(check + help**

I realized my mistake, i was only finding the resultant for the velocity, not the momentum together, if i do not convert km/h into m/s i get the momentum as 1.24*10^5 is that correct?

**Physics - Collision in teo dimensions(check + help**

Car A, with mass of 1735kg, was traveling north at 45.5km/h and car B, with a mass of 2540kg, was traveling west at 37.7km/h when they collided at an intersection. if the cars stuck together after the collision, what was their combined momentum? Was the collision elastic or in...

**Physics - Collision in one dimension**

The mass of a uranium-238 atom is 3.95*10^-25kg. A stationary uranium atom emits an alpha particle with a mass of 6.64*10^-27kg. If the alpha particle has a velocity of 1.42*10^4m/s, what is the recoil velocity of the uranium atom. Ans: i tried MaV'a = -MbV'b i happen ...

**Physics - mass of a galaxy**

A star at the edge of the Andromeda galaxy appears to be orbiting the center of that galaxy at the speed of about 200km/s. The star is about g*10^9AU from the center of the galaxy. Calculate a rough estimate of the mass of the Andromeda galaxy. Earth orbital radius is 1.40*10^8

**Physics - Dynamics in two dimensions**

is 153m the correct answer?

**Physics - Dynamics in two dimensions**

A sharpshooter shoots the bullet horizontally over level ground with a velocity of 300m/s. At the instant that the bullet leaves the barrel, its empty shell casing falls vertically and strikes the ground with a vertical velocity of 5m/s. How far does the bullet travel?

**Math - derivative of sinusoidal (check)**

a) Find a function y=f(x) that satisfies the differential equation dy/dx = fifth derivative. This is one of the questions in my practice test, I tried the basic equation of the trig function such as f(x)= sin(x) or f(x)=-sin(x) however in the fourth derivative they reach the s...

**Math - Rates of change and the number e (check + h**

Let f(x)= (1/b)^x for b>1, and left g(x) = (f'(x))/(f(x)) a) Predict the shape of the graph of g(x). it will be a straight line, since ln(1/b) will be a constant b) Test your prediction by exploring two specific cases. Values of (1/2) and (1/10) c) Summarize your findin...

**Math - derivative of sinusoidal (check + help)**

h(t) 0.6cos(2t) + 08 sin(t) h'(t) = v(t) = -1.2sin(2t) + 0.8cos(t) find the vertical displacement when the velocity is 0.8m/s how do i solve v(t) = 0.8m/s I tried the normal way by equating and factoring, however two answers are obtained and the second method is the identi...

**Math - app of sinusoial derivatives (help+check)**

An oceanographer measured a set of sea waves during a storm and modelled the vertical displacement of waves in meters using the equation h(t)=0.6cos2t+0.8sint, where t is the time in seconds. a) Determine the vertical displacement of the wave when the velocity is 0.8m/s Ans: -...

**Math - app of Sine and Cosine & thier Derivatives**

An oceanographer measured a set of sea waves during a storm and modelled the vertical displacement of waves in meters using the equation h(t)=0.6cos2t+0.8sint, where t is the time in seconds. a) Determine the vertical displacement of the wave when the velocity is 0.8m/s Ans: -...

**Math- pplication of Sin and Cos&thier derivative**

An oceanographer measured a set of sea waves during a storm and modelled the vertical displacement of waves in meters using the equation h(t)=0.6cos2t+0.8sint, where t is the time in seconds. a) Determine the vertical displacement of the wave when the velocity is 0.8m/s b) Det...

**calculus**

correct answer! dy/dx = cosx-xsinx.

**Physics - Double slit experiment**

For a double-slit interference, what would happen to the distance between the bright fringes if you: a) Decreased the distance between the slide and the screen b) Increased the separation between the slits c) Decreased the distance between the laser apparatus and the slide d) ...

**Physics - Hydrogen Emission spectrum **

a) Describe the emission spectrum of a hydrogen discharge tube b) Explain why different color lines appeared in different position in the spectrum. Use a suitable atomic model to help construct your answer. c) Explain how do you decide if the lines observed are of the first or...

**physics**

A Pyrex flask in a refrigerator at -8 degrees Celsius is filled to the top and holds exactly 1000cm^3 of ethyl alcohol. If the refrigerator fails, how much alcohol spills by the time the temperature reaches 22 degrees Celsius? The coefficient of volume expansion of ethyl alcoh...

**Physics - Hydrogen discharge tube**

a) Describe the emission spectrum of a hydrogen discharge tube b) Explain why different color lines appeared in different position in the spectrum. Use a suitable atomic model to help construct your answer. c) Explain how do you decide if the lines observed are of the first or...

**Physics - Double slit experiment**

For a double-slit interference, what would happen to the distance between the bright fringes if you: a) Decreased the distance between the slide and the screen b) Increased the separation between the slits c) Decreased the distance between the laser apparatus and the slide d) ...

**English - examples of socio-cultural norms**

Please give me loads of examples of socio-cultural norms

**Math - derivatives of cos and sin fucntions**

you mean y=2x for the first line...because I did something similar however I took the limit, since cos x can not have y values larger than 1 or -1, i took 2cosx=1 i get zero and using both methods:Y-Y1=m(X-X1) and y=mx+b i get y=2x. i checked it using a graphical calculator th...

**Math - derivatives of cos and sin fucntions**

a) Find an equation of a line that is tangent to y=2sinx and whose slope is a maximum value. b) Is there more than one solution? Explain.

**Math - derivative of cosine**

y=8cos((1/2)x)+10 dy/dx = -4sin((1/2)x) What is the maximum slope from 0 - 4(pi)? I tried equating the endpoints, but it does not work, can someone teach me how to find maximums and minimums?

**Physics - Scientific models**

a) Do you believe that some current accepted scientific models or theories might be held in high regard because of the structure of the scientists who proposed them? b) Suggest on possible model or theory that is currently accepted by a majority of people that you feel might b...

**Physics - wavefronts and wavelets**

Describe how the wavelets that form in the wavefront apparently vanish behind it?

**Physics - Sound Energy (check + help)**

Sound, a form of energy can be modeled by using two distinctly different approaches. a) Describe the propagation of sound energy through air by discussing the motion of individual particles. Include possible mathematical equations that might apply. Ans: Sound energy propagatio...

**Physcis - scientifc models and theories.**

a) Do you believe that some current accepted scientific models or theories might be held in high regard because of the structure of the scientists who proposed them? b) Suggest on possible model or theory that is currently accepted by a majority of people that you feel might b...

**Physcis - Wavefront and wavelets**

Describe how the wavelets that form in the wavefront apparently vanish behind it?

**Physics - Sound Energy (check + help)**

Sound, a form of energy can be modeled by using two distinctly different approaches. a) Describe the propagation of sound energy through air by discussing the motion of individual particles. Include possible mathematical equations that might apply. Ans: Sound energy propagatio...

**Physics - Sound Energy propagation**

Sound, a form of energy can be modeled by using two distinctly different approaches. a) Describe the propagation of sound energy through air by discussing the motion of individual particles. Include possible mathematical equations that might apply. Ans: Sound energy propagatio...

**Physcis -wavelets and wavefronts**

Describe how the wavelets that form in the wavefront apparently vanish behind it?

**Physcis - scientifc models and theories.**

a) Do you believe that some current accepted scientific models or theories might be held in high regard because of the structure of the scientists who proposed them? b) Suggest on possible model or theory that is currently accepted by a majority of people that you feel might b...

**Physics - gravitational fields**

The planet Neptune has gravitational field intensity of 10.3nékg at a height of 1.00*10?6m above its surface. If the radius of Neptune is 2.48*10?7m, what is its mass

**Physics - centripetal acceleration**

What is the centripetal acceleration of a satellite orbiting Saturn at the location exactly on Saturn radius above the surface of Saturn

**Physics - Charge on sphere (check + help)**

Two 2.0g spheres are attached to each end of a silk thread 1.20m long. The spheres are given identical charges and the midpoint of the thread is then suspended from a point on the ceiling. The spheres come to rest in equilibrium, with their centers 15cm apart. What is the magn...

**Physics - Spring balls**

A 275g ball is resting on top of the spring that is mounted on the floor. You exert a force of 325N on the ball and it compresses the spring 44.5cm. If you release the ball from the position, how high above the equilibrium position of the spring-ball system will the ball rise?

**Math - derivative of a rational function**

find the 1st derivative of f(x) = x/(x-1)2 Is the 1st derivative f'(x)= -x-1/(x-1)^3

**Health Econ**

The probability of death from running a red light is 15%. People who run the red light do not want to lose the 2 minutes where they have to wait for the light to turn green again. Assume the average salary is $25 an hour. Compute the value of life using the Jones-Lee approach.

**ap chemistry**

Definetly E

**French **

I am thinking it should have been "irez" instead of "allez". which would be future progressive.

**french**

b, august of course come on!

**french**

a.