# Posts by Melissa

Total # Posts: 1,316

**Physics**

A 3.90×10^2kg cube of ice at an initial temperature of -18.0degreesC is placed in 0.480kg of water at 41.0degreesC in an insulated container of negligible mass. Calculate the change in entropy of the system. I found the equilibrium temperature to be at 304.9K, then used ...

**chemistry**

what is the molarity of 275mL of a solution containing 23.83 mg of Mg Cl(2)<small 2

**Statistics**

A group of doctors is trying to see if a vaccine causes a certain type of disease. They take individuals with the certain disease and individuals without the disease. They then use research to estimate the relative incidence of the onset of the disease after the vaccination. ...

**physics**

An air puck of mass m1 = 0.45 kg is tied to a string and allowed to revolve in a circle of radius R = 1.0 m on a frictionless horizontal table. The other end of the string passes through a hole in the center of the table, and a mass m2 = 1.10 kg is attached to it. The ...

**physics**

A light spring of spring constant k = 160 N/m rests vertically on the bottom of a large beaker of water. A 5.00 kg block of wood (density D = 700 kg/m3) is connected to the spring, and the block ? spring system is allowed to come to a static equilibrium

**Chem**

what mass of calcium oxalate can be dissolved in 180 ml of distilled water before a precipitate forms?

**statistics**

In one history class, 34 students took an exam. The mean of the exam was 52 with a standard deviation of 13. If the instructor is going to assume data are normally distributed and assign grades on a curve, then she will assign an A to the top 10% of the class, B's to the ...

**english**

At my son’s very first softball game his team did not do very well. No one seemed to be able to hit the ball or run the bases when they were up to bat. When they were in the field they would either run from the ball or be nowhere near it when they attempted to catch it. ...

**science**

What are the hard and fast rules of Science, if any?

**6th grade**

Each letter in each questio stands for a 1-digit number. in each question, no two letters maystand for the same number. Two separate problems are unrelated.Find a value for each letter MOON Use Numbers 4,7,5,6,2.8,9,3 x AT ____ ACROSS

**chemisty**

what is the molarity of ZnCl2 that forms when 30.0 g of zinc completely reacts with CuCl2 according to the following reaction? Assume a final volume of 285 mL. Zn(s) + CuCl2(aq)--> ZnCl2(aq) + Cu(s)

**U.S history**

My two colonies are New Jersey and Pennsylvania.How are they similar and how are they different?Which one would you live in,and why?

**us history**

Think about two colonies.How are they similar?How are they different?Decide which colony you would like to live in.

**physics**

I know this has been posted many times but I keep trying and cannot get the right answer, A place kicker must kick a football from a point 39.9 m from a goal. As a result of the kick, the ball must clear the crossbar, which is 3.05 m high. When kicked the ball leaves the ...

**physics**

I know this has been posted many times but I keep trying and cannot get the right answer, A place kicker must kick a football from a point 39.9 m from a goal. As a result of the kick, the ball must clear the crossbar, which is 3.05 m high. When kicked the ball leaves the ...

**calculus**

Have you found an answer yet?

**Math**

I figured it out 1 gallon = 8 pints and to figure the 3/4. you take 3/4 x 8/1= 24/4 and that = 6. so 6+8=14

**Math**

nick has 1 3/4 gallon of milk how many pints does nick have. I think it is 14.

**Algebra**

Consistent and independent?

**Algebra**

3x-9y=63 2x-6y=-18 Solve system of equations by graphing then classify as Independent on dependent and consistent or inconsistent?

**Algebra**

I still don't understand?

**Algebra**

One canned juice is 20% orange juice: another is 10% orange juice. How many liters of each should be mixed together in order to get 10L that is 13% orange juice.How many liters of the 20%? How many liters of the 10%?

**math**

how many 10s are in 1,000?

**Chemistry**

Ethanol burns to produce 1300.0 kJ/mol and has a heat capacity of 65.6 J/mol·K. If Dr. Porter has 1.00 L of liquid ethanol (density = 0.789 g/mL), what is the minimum mass of fuel that should be removed and burned to heat the remaining ethanol from 25 °C to 90 °...

**Chemistry**

Hydrofluoric acid etches glass by reacting with the silica in it according to the following equation. H° = 54.5 kJ and S° = 436.5 J/K Calculate G° at 25°C for this reaction.

**Physics**

Newton's third law says that for every action there is an opposite and equal reaction. Does that mean that the the average thrust force the gas exerts on the engine and rocket would each be 5 N?

**Physics**

A typical model rocket engine exerts an average force of 5 N on its exhaust gas. How much average thrust force does the gas exert on the engine and rocket?

**Chem**

2 H2O (l) → 2 H2 (g) + O2 (g) Using the thermodynamic values to calculate accurate values of ΔHr and ΔSr, will the reaction be product favored at high temperature? Why? r stands for reaction

**Chem. only regarding formula.**

how do do calculate ΔHr and ΔSr?

**Chem. thankss!!!**

1.0 mol of water (c=4.184 J/g.oC), 1.0 mol of ethanol (c=2.46 J/g.oC), 1.0 mol of carbon tetrachloride (c=0.861 J/g.oC), and 1.0 mol of ethylene glycol (c=2.42 J/g.oC) at 50oC were each placed into a separate coffee cup calorimeter and the temperature recorded. The temperature...

**Chem**

In an experiment 50 g of a metal was heated to 100oC and placed in 200 g of a liquid at 25oC. Which of the following combinations of metal and liquid will produce the largest temperature increase in the liquid? (Assume that there is no energy transfer to the surroundings.) ...

**CHEM.**

Zinc is often used to calibrate calorimeters because it undergoes a very sharp phase transition from the solid to the liquid at 419.5oC. Calculate the enthalpy change when 5 g of zinc metal is heated from 100oC to the point where the entire sample is melted. (The heat of ...

**CHEM. help please**

Consider a system of 3 molecules, A, B, and C. Suppose the 3 units of energy can be distributed over the three atoms where each atom can have no energy, one unit, two units or 3 units of energy. Assume each of the 10 possible arrangements is equally probable. What's ...

**Chem Help please**

Consider a system of 3 molecules, A, B, and C. Suppose the 3 units of energy can be distributed over the three atoms where each atom can have no energy, one unit, two units or 3 units of energy. Assume each of the 10 possible arrangements is equally probable. What's ...

**Calculus**

Given the demand function q=173-5p, determine the price where demand has unit elasticity.

**Calculus**

Given the demand function q=173-5p, determine the price where demand has unit elasticity.

**Calculus**

the demand for ground chuck(hamburger) in a certain region of the US is given by q= 3.41p^-0.22. is the demand for ground chuck elastic or inelastic

**Calculus**

a local office supply store has an annual demand for 50,000 cases of photocopier paper per year. it costs $2 per year to store a case of photocopier paper, and it costs $50 to place an order. Find the optimum number of cases of photocopier paper per order

**CHemistry**

Use the bond energies given in the "Bond Energy" table (can be gained from google) to estimate the delta Ho for the reaction given below. 2ClF3(g) + 2O2(g) Cl2O(g) + 3OF2(g) I did this: 1530 + 996 - (410 + 570) = 1546. But the answer was wrong. I don't know where...

**Chemistry**

Use the bond energies given in the "Bond Energy" table (can be gained from google) to estimate the delta Ho for the reaction given below. 2ClF3(g) + 2O2(g) Cl2O(g) + 3OF2(g) I did this: 1530 + 996 - (410 + 570) = 1546. But the answer was wrong. I don't know where...

**Chemistry- helpp!**

The equation for synthesis of the poisonous gas COCl2 is CO(g) + Cl2(g)COCl2 If 43.2 kJ of energy is evolved when 39.5 g of COCl2 is synthesized, what is the molar enthalpy for this synthesis? THANK YOU!

**Chemistry**

Calculation of the sodium chloride (NaCl) content and evaporation: 1. The amount of sodium chloride in the original mixture may be determined indirectly by adding the masses of ammonium chloride and sand together and subtracting the sum from the initial sample mass of 10g. 2. ...

**Chemistry**

I am doing a lab online and have no clue on how to get started with the following questions? Please Help me! 1. Calculate and record the following (in grams): (a) mass of NaCl by subtraction of other components: (b) measured mass of NaCl after boiling away water: 2. Calculate ...

**chemistry**

What volume (in Liters) of hydrogen must react to form 17.0L of ammonia according to the following balanced equation: N2(g) + 3H2(g) --> 2NH3(g) Ratio from equation is H : NH3 = 3 : 2 = 3/2 : 1 = 17x3/2 : 17 = 25.5 : 17 17 L of hydrogen can you check my work is this right?

**college chemistry**

so it would be (1)(.0036)=n(.0821)(273)?

**college chemistry**

A volume of 0.285 L of a gas at STP weighs 0.537 g. Calculate the molar mass of the gas (1)(0.285) = n(0.0821)(273). .0036 is this correct?

**English**

make 2 words, first one 8 letters and second work 4 letters out of these s l r t n r u p a e s a

**english**

I'm doing an analysis on a class text and a self chosen related text and one of the things the sheet says to do is to identify and define the context of my related text. What does this mean?

**Sociology**

How does studying social institutions help sociologists understand society?

**Math-Calculus**

If f(x)=5ex+4xe find f'(x) .

**Help! Physics!!**

Water flows (v = approx 0) over a dam at the rate of 660 kg/s and falls vertically 86 m before striking the turbine blades. Calculate the rate at which mechanical energy is transferred to the turbine blades, assuming 53% efficiency. Express your answer using two significant ...

**Help! Physics!!**

A 120-kg crate, starting from rest, is pulled across a floor with a constant horizontal force of 400 N. For the first 17 m the floor is frictionless, and for the next 17 m the coefficient of friction is 0.34. What is the final speed of the crate? Express your answer using two ...

**college physics**

they have the same speed as each other at the instant they hit the ground. Trick question!

**Algebra**

Write 9850 in scientific notation

**AP English Literature**

I really like that as a thesis statement. Thank you so much! (:

**AP English Literature**

No...? I don't think so. I just want to make a point about how it's wrong to take the rights of a newborn baby because their parents sacrificed themselves to cross the border, and have their child be born in America, so it's easier for their child to have a '...

**AP English Literature**

I looked over it, but for some reason it didn't really help me.

**AP English Literature**

The thesis can only be in one place, which is the ending of the introduction. My thesis: "Everyone is entitled to their own opinion on how this problem should end, but it must be resolved." This "Illegal immigrants are now having "anchor babies" in the...

**AP English Literature**

Well so far I have my intro. which is this: Throughout the years, it has been known that if one's newborn is born in America, they have automatic citizenship, regardless of what their parent's situation may be; which is what the 14th Amendment states. Illegal ...

**AP English Literature**

I basically want to solve this problem and I want to talk about people's reaction, pros & cons, etc.

**AP English Literature**

I'm doing a research essay about "anchor babies", or in other words, babies born from illegal immigrants. How would you write a good thesis?

**Physics**

An airplane flies at 200.0 km/h relative to the air. What is the velocity of the plane relative to the ground if it flies during the following wind conditions? a. a 50.0-km/h tailwind b. a 50.0-km/h headwind.

**Physical chemistry**

Estimate the vapor pressure of sea water at 20C given that the vapor pressure of pure water is 2.338 kPa at that temperature and the solute is largely Na+ and Cl- ions, each present in about .50 mol/dm^3. I'm pretty sure the formula to use is pj=xjpj'. Where pj' is...

**Medical Terminology**

Treatment that's designed to reduce the intensity of painful symptoms but that doesn't produce a cure is

**Physics**

So in solving the answer it would be F=(8.99E9)*(2.5E13*1.6E-19)*(2.5E13*1.6E-19)/.50^2? If so, I don't think I did it right. I ended up with an answer of .57536

**Physics**

Two very small spheres are initially neutral and separated by a distance of 0.50 m. Suppose that 2.50 x 10^13 electrons are removed from one sphere and placed on the other. What is the magnitude of the electrostatic force that acts on each sphere?

**Mastering Chemistry**

Molarity(M)=amount (mol) of solute/volume (L)of solution. im gonna guess you have 11.0g and 75.0 mL convert ml to L -> 75/1000=0.075L ->177 molar mass of Luminol 11.0 x(1/177)/0.075 = your answer in units of M

**Calculus**

If h(t) represents the height of an object above ground level at time t and h(t) is given by h(t) = −16t2 + 96t + 1, find the height of the object at the time when the velocity is zero.

**geometry**

If m<PQR=(10x-7),m<RQT=5x, and m<PQT=(4x=6)

**Chemistry**

What is the molecular, ionic and net ionic formula for Acetic acid and sodium nitrate Molecular: Ionic: Net Ionic:

**physics**

When it says magnitude of velocity is that the same as the final velocity before impact? The word "magnitude" threw me off.

**physics**

A child throws a ball with an initial speed of 8 m/s at an angle of 40 degrees above the horizontal. The ball leaves her hand 1 m above the ground. How long is the ball in flight before it hits the ground? What is the magnitude of the ball's velocity just before it hits ...

**physics**

Richard is driving home to visit his parents125 mi of the trip are on the interstate highway where the speed limit is 65 mph Normally Richard drives at the speed limit, but today he is running late and decides to take his chances by driving at 80 mph.how many minutes will he ...

**Chemistry**

A mixture contains only NaCl and Al2(SO4)3. A 1.45-g sample of the mixture is dissolved in water and an excess of NaOH is added, producing a precipitate of Al(OH)3. The precipitate is filtered, dried, and weighed. The mass of the precipitate is 0.107 g. What is the mass ...

**physics**

Mary needs to row her boat across a 120 m -wide river that is flowing to the east at a speed of 1.4 m/s. Mary can row the boat with a speed of 2.0 m relative to the water. 1. How long does it take Mary to reach the opposite river bank ? 2.If Mary rows straight north, how far ...

**Chemistry**

How many moles of H2 can be produced from 7.74g SrH2? equation:SrH2 + 2H2O = Sr(OH)2 + 2H2

**Physical chemistry**

Calculate the pressure exerted by 1.0 mol C2H6 behaving as a perfect gas

**Calculus**

If h(t) represents the height of an object above ground level at time t and h(t) is given by h(t)=-16t2+11t+1 find the height of the object at the time when the speed is zero.

**Calculus**

ignore the "d=". Sorry!

**Calculus**

Let F(s)=5s2+5s+4 . Find a value of d greater than 0 such that the average rate of change of F(s) from 0 to d equals the instantaneous rate of change of F(s) at s=1. d=

**Chemistry**

I am really having trouble answering this question, can someone help? A binary compound between an unknown element E and hydrogen contains 91.27% E and 8.73% H by mass. If the formula of the compound is E3H8, calculate the atomic mass of E.

**Chemistry**

Fungal laccase, a blue protein found in wood-rotting fungi, is 0.390% Cu by mass. If a fungal laccase molecule contains four copper atoms, what is the molar mass of fungal laccase?

**Chemistry**

Consider equation 3A+B=C+D. You react 4 moles of A with 2 moles of B. Which of the following is true? 1) Limiting reactant (L.R.) is one with higher molar mass 2) A is L.R. because you need 6 moles of A and have only 4 moles 3) B is L.R. because you have fewer moles of B than ...

**ELAC**

Consider equation 3A+B=C+D. You react 4 moles of A with 2 moles of B. Which of the following is true? 1) L.R. is one with higher molar mass 2) A is L.R. because you need 6 moles of A and have only 4 moles 3) B is L.R. because you have fewer moles of B than A 4) B is L.R. ...

**9th grade math**

x to the 2nd power if x = 3/4 how do you find 3/4th to the 2nd power? 3/4th times 3/4th right? so the answer would be 9/16ths.. right?

**math**

You drove 2695 miles in 35 hours. (1) What is your average rate of change? (2) Suppose you can drive that distance at a legal 75 mile per hour rate. How long should it take you to complete the trip? (3) Suppose you are driving that distance at an illegal 86.8 miles per hour ...

**College Mathematics**

You drove 2695 miles in 35 hours. (1) What is your average rate of change? (2) Suppose you can drive that distance at a legal 75 mile per hour rate. How long should it take you to complete the trip? (3) Suppose you are driving that distance at an illegal 86.8 miles per hour ...

**english**

In the sentence: Hello, my name is Melissa. What is the predicate?

**algebra**

a student writes 5y.3 to model the relationship the sum of 5y and 3.explain the error

**The elements and Principles of Design**

9-D just took the test

**Math**

How do you do a division problem?

**pre-algebra**

2/x-5=1/x+2 the teacher said i got it wrong when i got -1/7 he got -9 if that is please explain.

**accoutning**

what is an advantage of the partnership form of business organization is? 1. unlimited liability 2. mutual agency 3. ease of formation 4. limited life

**Math-Stats**

The Acme Candy Company claims that 60% of the jawbreakers it produces weigh more than .4 ounces. Suppose that 800 jawbreakers are selected at random from the production lines. Would it be unusual for this sample of 800 to contain 418 jawbreakers that weigh more than .4 ounces?

**geometry**

you are building a ramp that will be in the shape of a perfect right-angled triangle. The vertical height of th ramp will be 10 feet. the horizontal base of the ramp will be 15 feet. what will be the length of the downward sloping side of the ramp?

**Chemistry**

Write the chemical formulas for the compounds containing each of the following: a) one calcium atom for every two iodide atoms. b) two nitrogen atoms for every four oxygen atoms. c) one silicon atom for every two oxygen atoms. d) one zinc atom for every two chlorine atoms

**Chemistry**

Write the chemical formulas for the compounds containing each of the following: a) one calcium atom for every two iodide atoms. b) two nitrogen atoms for every four oxygen atoms. c) one silicon atom for every two oxygen atoms. d) one zinc atom for every two chlorine atoms

**Statistics**

Using the major League Baseball Data set available through the "Data Sets" lin in the materials section, answer the research question of whether the number of wins of a team can be explained linearly by the size of stadium, ERA, and stolen bases. Prepare a 750-1,050 ...

**algebra**

1800 kilometers ?

**algebra**

A stack of $10 bills is worth $90 billion dollars. What is the height of the stack in kilometers? Assume each bill is .2 millimeters high.