Friday

February 5, 2016
Total # Posts: 257

**Chemistry**

Another proposed mechanism problem: H2O2 + I ---> H2O +IO slow H2O2 + IO ---> H2O + O2 + I fast Which of the following statements in incorrect? a.) IO is a catalyst b.) I is a catalyst c.) The net reaction is 2H2O2 ---> 2H2O + O2 I would choose B, since IO is shown as...
*February 19, 2013*

**Chemistry**

The decomposition of ozone may occur through the two-step mechanism shown below: step 1 O3 ----> O2 + O step 2 O3 + O ---> 2O2 The oxygen atom is considered to be: a catalyst or reaction intermediate? How am I supposed to be able to tell the difference between the two? I...
*February 19, 2013*

**Chemistry**

Which of the following solutes, dissolved in 1000g of water, would provide a solution would the lowest freezing point? .030 mol of BaCl2, CO(NH2)2, CaSO4, CH3COOH, or .030 mol of NH4NO3 Again, the steps needed to determine for the freezing point.
*February 19, 2013*

**Chemistry**

Which of the following solutes in aqueous solution would be expected to exhibit the smallest freezing-point lowering (assuming ideal behavior? 0.1 m NaCl .2 m CH3COOH .05 m Al2(SO4)3 .1 m MgCl2 .25 m NH3 What would be the steps to picking the right option? Because just picking...
*February 19, 2013*

**Chemistry**

Which of the following pure liquids is the best solvent for sodium fluoride? CCl4 C2C6 HCl BCl3 or PCl5 My guess would be either CCl4 or C2C6, I need to know the reasoning behind the correct answer.
*February 19, 2013*

**Chemistry**

In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds? I found the concentration to be 1.25 x 10-2 M But then how do I find the rate ...
*February 18, 2013*

**Chemistry**

Cyclopropane rearranges to form propene: CH2CH2CH2 --> CH2=CHCH3 by first-order kinetics. The rate constant is k = 2.74 x 10-3 s-1. The initial concentration of cyclopropane is 0.290 M. What will be the concentration of cyclopropane after 100 seconds?
*February 17, 2013*

**Chemistry**

The decomposition of N2O5(g) --> NO2(g) + NO3(g) proceeds as a first order reaction with a half-life of 30.0 seconds at a certain temperature. If the initial concentration [N2O5]0 = 0.400 M, what is the concentration after 120 seconds?
*February 17, 2013*

**Chemistry**

In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds?
*February 17, 2013*

**Chemistry**

2A + B2 + C --> A2B + BC Run # Initial Rate (M-1s-1) (A)o (B)o (C)o 1 1.6 x 106 1.2 M 1. x 10-2 M 1.0 M 2 1.6 x 106 2.4 M 1. x 10-2 M 1.0 M 3 3.2 x 106 1.2 M 2. x 10-2 M 1.0 M 4 6.4 x 106 1.2 M 1. x 10-2 M 2.0 M What would be the rate-law expression of the reaction above?
*February 17, 2013*

**Chemistry **

What is the vapor pressure of a aqueous solution containing 10 % (by weight) ethylene glycol (62 g/mol) at 25 °C. PH2O = 24.3 torr at 25°C?
*February 10, 2013*

**Chemistry **

When 1.150 grams of an unknown nonelectrolyte dissolves in 10.0 grams of water, the solution freezes at -2.16°C. What is the molecular weight of the unknown compound? Kf for water = 1.86°C/m. -2.16 x m/-1.86 = 1.16 1.16/ .010 kg of water= 116 1.150/116= 9.91 g/mol is ...
*February 10, 2013*

**Chemistry **

A solution contains 10.0 g pentane, C5H12, 10.0 g hexane, C6H14 and 10.0 g benzene, C6H6. What is the mole fraction of hexane? I figured the equation would be: ___ M Hexane x 10 Divided by 30 =Mole fraction of Hexane?
*February 10, 2013*

**Chemistry **

What mass of water must be used to dissolve 20.0 grams of ethanol, C2H5OH, to prepare a 0.0500 molal solution of ethanol?
*February 10, 2013*

**Chemistry **

What is the molality of an aqueous solution that is 10.0% ethanol, C2H5OH, by mass?
*February 10, 2013*

**Chemistry **

The rate of a reaction A ---> B is expressed by the rate expression rate=k(A)2. If the molar concentration of A is tripled, the rate of the reaction should increase by a factor of some many?
*February 9, 2013*

**math**

how do I write equation for the following? input a 20/28/36/44/52 output b 5/7/9/11/ ? ? is 13
*January 23, 2013*

**Math**

You have 2/3 bag of flour. Use 3/4 of the flour to make cookie dough. How much of the entire bag do you use to make cookie dough?
*December 17, 2012*

**Math**

The teacher asked Laura to give each student 2/5 sheets of paper. If there are 20 students in the class how much paper did Laura pass out?
*December 17, 2012*

**GRAMMAR**

WRITE AN ARTICAL ABOUT CALIFORNIA GOLD RUSH
*December 11, 2012*

**chemistry**

My chem book gives me the following Hess' Law example: Mg + 2HCl --> H2 MgCl2 Delta H1 MgO +2HCl --> H2O +MgCl2 Delta H2 H2 + 1/2 O2 --> H2O Delta H3=-68.3kcal The desired reaction is the formation reaction of MgO as follows: MgS +1/2 O2 --> MgO Delta H final= ...
*December 6, 2012*

**physics**

A weightlifter has a basal metabolic rate of 80.0 W. As he is working out, his metabolic rate increases by about 650 W. (a) How many hours does it take him to work off a 450-Calorie bagel if he stays in bed all day? (b) How long does it take him if he’s working out? (c) ...
*November 28, 2012*

**precalculus**

My book says a way for me to graph/plot points for my function is to write it in exponential form. For example. "Graph (fx)= log base 2(x-2) y=log base 2 (x-2) x-2=2^y x=2^y + 2 So now I can just plug any y value in to get my x value to graph my translated graph. So I was...
*November 21, 2012*

**precalculus **

When asked to sketch the graph of g(x)= -e^(x+1) +1, how do I turn this equation into exponential form? Or can I? I always get confused on what to do especially when I need to the x part of the equation out of the exponent.
*November 21, 2012*

**precalculus **

My book tells me to solve each exponential equation. I am given a lot of problems such as 6^x+1 = 4^2x-1 where I use In in the problem to help get my answer. However, in the same section, the book starts giving me problems such as 3(2)^x-2 +1=100 and .05(1.15)^x =5 etc. Where ...
*November 21, 2012*

**precalculus **

e^3x-7 x e^-2x =4e First step I get e^1x-7 =4e For the example in my book, the next step they divided by e. But I have no idea how to do this, or what involves?
*November 21, 2012*

**precalculus **

log_6(2x + 4)=2? 5 In x=10? log(x+25)=1+ log(2x-7)?
*November 21, 2012*

**precalculus**

No reason, basically the equation is supposed to read 3^log base 3^8?
*November 21, 2012*

**precalculus **

x= 3^log_3_^8 ? The log being in the exponent is throwing me off.
*November 21, 2012*

**Precalculus **

Solve (log x)^2 = log x Also, when will their be a possibility that an equation will have an extraneous solution? Like if you got two solutions for a log equation, will a negative solution for x automatically be extraneous?
*November 20, 2012*

**Pre calculus **

Okay, I'm really fuzzy about my log and exponential chapter. For example, solving some exponential equation such as e^3x-7 x e^-2x=4e I assume I start this equation by taking the natural log of both sides, but how will I know just by looking at an equation weather I need ...
*November 20, 2012*

**science**

What is the acceleration of a 50kg person is pushed with a force of 4N
*November 15, 2012*

**chemistry**

when Na compounds are heated, thy give off a light of 5890 A. If 1 x 10-4 mole of Na atoms each give off a photon of this wavelength, how many kilojoules of energy are given off?
*November 14, 2012*

**chemistry**

consider the following changes at constant temperature & pressure H2O(s) --yields-- H20(l); Delta H1 H2O(l) --yields-- H2O(g); Delta H2 H2O(g) --yields-- H2O(s); Delta H3 Using Hess's law, the sum of the deltas is a. equal to 0 b. sometimes greater than zero, sometimes ...
*November 14, 2012*

**chemistry**

since q= 100 mL x 4.18 x 8.01 =3348.18/.06= 55803. J to kJ= 55.803 should be the final answer, right? Because the answer key on my quiz says it's -55.8 kJ. I'm so confused because I thought for sure it would positive, especially since in the equation it says increases ...
*November 14, 2012*

**chemistry**

When 50.0mL of 1.20 M of HCl (aq)is combined with 50.0mL of 1.30 M of NaOH (aq) in a coffee-cup calorimeter, the temperature of the solution increases by 8.01 Degrees C. What is the change in enthalpy for this balanced reaction? HCl(aq) + NaOH(aq) --yields-- NaCl(aq) + H20(l) ...
*November 14, 2012*

**chemistry**

A 94.7 g sample of silver (s= 0.237 J/(g x Degree C)), initially at 348.25 Degrees C , is added to an insulated vessel containing 143.6 g of water (s=4.18 J/(g x Degree C)), initially at 13.97 Degrees C. At equilibrium, the finial temperature of the metal-water mixture is 22....
*November 14, 2012*

**chemistry**

I get -3113 as my answer when I plug in 30.6 as the molar mass when the teacher said it should be around -225 as the final answer?
*November 14, 2012*

**chemistry**

At constant pressure and 25 degrees C, what is delta H for the reaction 2C2H6(g) + 7O2(g) --yields-- 4CO2(g) + H2O(l) if the complete consumption of 11.3 g of C2H6 releases -586.3 kJ of heat energy? (11.3=.38 mol C2H6)
*November 14, 2012*

**math**

is 0.14 equal to 0.104
*October 30, 2012*

**Art**

If a painter paints 8 different pictures to get a better perspective and then only selects 1 picture to illustrate her mood: what would this be called?
*October 9, 2012*

**Math **

A basket containing 80 eggs weighs 2kg 300g. The same basket containing 60 eggs weighs 1kg 700g. Find the mass of the empty basket.
*July 28, 2012*

**healthcare management**

Write a 1,400- to 1,750-word paper on essential communication in a community crisis situation described in the scenario. Include the following in your paper: • The individuals or groups that will be communicating inside and outside the organization during this crisis ...
*July 26, 2012*

**math **

Fill in the blanks with the numbers that complete the sequence, and briefly explain the rule you used 2,3,5,5,8,7,11 _,_,_,17,_,_,_ 3,4,3,4,5,3,4,5,_,_,_,_,_,7 1,2,1,1,2,3,2,1,1,2,3,4,3,_,_,1,2,_,_,_,_,_,2
*June 2, 2012*

**math**

yes 13,15,17,19 thanks :)
*June 2, 2012*

**math**

that would give me 16 but thats not an odd number
*June 2, 2012*

**math**

Use algebra pieces and mental arithmetic to determine four consecutive odd numbers who sum is 64. Sketch and label your algebra piece model and explain how you solved the problem.
*June 2, 2012*

**math**

thanks i really appreciate it
*June 1, 2012*

**math**

what do you mean there are 6 wheels left over?
*June 1, 2012*

**math**

Levinson’s Hardware has a number of bikes and tricycles for sale. There are 27 seats and 60 wheels all told. Determine how many bikes and tricycles there are in the store
*June 1, 2012*

**Math**

gerald had a gross pay last wk of $980.00, If his total deductions were 161.35, what was his net pay?
*May 27, 2012*

**Cardiovalscular**

Phonology refers to the science which treats A. blood disorders. B. vocal sounds. C. heart rhythms. D. nutritional deficiencies. MY ANSWER IS A
*April 22, 2012*

**consumer math**

2. Use the monthly payment table and this table to answer the following questions. Loan APR Years Monthly Payment Total Payment Interest $6,700 13.5% 5 A B C $8,720 12.5% 15 D E F $20,230 11.5% 20 G H I Find A. (Points : 1) 3. Find B. (Points : 1) 4. Find C. (Points : 1) 5. ...
*February 28, 2012*

**calculus**

Actually, it's not homework. It's a practice problem that I don't even get credit for. I've done the problem multiple times but didn't think I should type up all my work for the wrong answers that I keep getting. I don't know who the other person is ...
*February 2, 2012*

**calculus**

If f(x)=x2+10, find and simplify the following: (a) f(t+8)= (b) f(t5+8)= (c) f(5)= (d) 5f(t)= (e) (f(t))2+8=
*February 2, 2012*

**Algebra**

The linear equation y=0.15x+0.79 represents an estimate of the average cost of gas for year x starting in 1997. the year 1997 would be represented by x=1, for example, as it is the first year in the study. similarly, 2005 would be year 9, or x=9 A) what year would be ...
*January 6, 2012*

**algebra**

42x^5 _____ 7x
*December 10, 2011*

**MATH HOMEWORK HELP PLEASE ANSWER**

Erica invests $10,000 at 5% interest compounded annually. How much interest will Erica earn in 3 years
*November 3, 2011*

**pre algebra with pizzazz 239**

why didn't the circus managers want their human cannonball to quit?
*October 27, 2011*

**statistics**

Facebook reports that the average number of Facebook friends worldwide is 175.5 with a standard deviation of 90.57. If you were to take a sample of 25 students, what is the probability that the mean number Facebook friends in the sample will be 190 friends or more?
*October 26, 2011*

**geometry**

DEFG is an isosceles trapezoid. Find the measure of <E.
*October 20, 2011*

**science**

You have 10 ml of a 1:10,000 solution of hydrogen peroxide (H2O2). What is the molar concentration of the solution?
*September 5, 2011*

**compostion and communiucation II**

DO YOU THINK BLOGGING AND INCREASED EXPOSURE TO INFORMAL WRITING HAS AN AFFFECT ON STUDENTS ACADEMIC WRITING QUALITY.
*August 16, 2011*

**Geometry**

If AB=5x+2 and AC=12x-2, what is BC?
*June 30, 2011*

**Maths C**

lol! i have the same assignment and im having trouble aswell. I cant find anything on weddles rule on the internet and it is not in my textbook.
*June 23, 2011*

**science**

cslculate the molarity of a solution of 10.0g MgCl2 in a 300.0ml of solution
*June 21, 2011*

**geometry**

How many hours will it take a bicyclist traveling 17.6 feet per second to finish a 90-mile race? Round your answer, if necessary, to the nearest tenth.
*June 7, 2011*

**geometry**

XY bisects and is perpendicular to line segments AB and CD . AB = 96 inches, and line segment AP = 52 inches. What is the length of XY ?
*May 24, 2011*

**algebra**

Actually is does make sense. drwls misinterpreted the question. It's asking for a decrease of 400% over 10 year and NOT a percent decrease. This means, that for year 1, the cost of a cell phone drop by 40%. At year 2 it dropped by another 40%, and on and on until year 10. ...
*May 15, 2011*

**Math**

1) 2 + (-3) = ? 2 - 3 = -1 2) (-7)(11) = ? - ( 7 * 11) - - (77) so (-7)(11) = -77
*May 13, 2011*

**Math**

Owes is negative/ gives is positive -455 + 86 = - 369 -369 -107 = - 476 - 476 + 348 = -128 So, after all that, he owes the company $128
*May 13, 2011*

**algebra**

what does the formula D=(b-c) represent
*May 7, 2011*

**pre algebra**

An area has been reforested. After 5 years , one of the tree is 2 meters tall. After six more years, the same tree is 3.2 meters tall. name 2 ordered pairs that can be used to to graph the information?
*May 4, 2011*

**math**

Max has the following colors of shirts: red, blud, green, yelllow, white, and orange. in how many different ways can he arrange the shirts in his closet?
*April 12, 2011*

**math**

On the fastest speedways, some drivers reach average speeds of 2 miles per minute. write the formula that gives the number of miles M that such driver would travel in x minutes. How would this driver travel in 38 minutes?
*April 11, 2011*

**science **

How many gallons of fossil fuel to make a gallon of each of the following? synfuel soy ethanol cellulosic electricity
*April 10, 2011*

**biology**

who made the first dna model and when
*February 17, 2011*

**Chemistry**

2. the pressure rises until a liquid-gas equilibrium is reached. A real life example of this is fire extinguishers which store CO2 as a liquid at room temperature at really high pressures. Im just a student, but I think that as the dry ice sublimes into gas at low pressures, ...
*January 31, 2011*

**Chemistry**

An ideal monatomic gas initially at 298 K and 1 atm pressure is expanded from a volume of 1 liter to 2 liters. Consider separately isobaric, isothermal and adiabatic expansions to accomplish this. In each case, calculate the following: a) The final temperature of the gas b) ...
*January 30, 2011*

**algebra 1**

Natalie made a mistake in the following problem. What line was the mistake made in? Show your work and give the correct answer. Line 1 6(4) ÷ 2 − 1 + 5 Line 2 6(4) ÷ 1 + 5 Line 3 24 ÷ 1 + 5 Line 4 24 + 5 Line 5 29
*December 22, 2010*

**Geometry**

Given triangleABC is congruent to triangleXYZ, if AB=3X-1, BC=5X+2, XY=7, and YZ=14, find X.
*December 13, 2010*

**5th grade**

Ginny has a pumpkin with a mass of 4.8kilograms. If .9 of its mass is water, how much of its mass is water? How much is not water?
*December 6, 2010*

**wordd**

Compare and contrast your abilities as an academic writer now as opposed to when you began your studies at college using four comparatives and four superlatives within your responses, explain what has led to these changes
*November 19, 2010*

**advanced math 6th grade**

how many positive integral factors does the number 36 have? I dont understand what that means or how to find the answer.
*November 17, 2010*

**11th grade**

stupid 10th grader
*November 16, 2010*

**11th grade**

9x^2=49 3x=7 x=7/3
*November 16, 2010*

**Physics**

A 67.0 kg base runner begins his slide into second base when moving at a speed of 3.5 m/s. The coefficient of friction between his clothes and Earth is 0.70. He slides so that his speed is zero just as he reaches the base. How much mechanical energy is lost due to friction ...
*November 14, 2010*

**english**

what type of verb tense is this? After reading about the successful steps to planning I am going to create a budget?
*November 10, 2010*

**College Chemistry**

please help! You are given an unknown, colorless, solution that may contain only one salt from the following set: NaA, NaB, NaC. In solution each salt dissociates completely into the Na+ ion and the anion A-, B-, or C-, whose properties are A is green, B is yellow, and C is ...
*November 10, 2010*

**9th grade math**

help
*October 26, 2010*

**Physics**

You drive due east at 78 km/h for 55 min. Then you follow a road going 60 degrees south of east, going 99 km/h for another 38 min . Find your total displacement.
*October 5, 2010*

**math**

Write a real world problem that you can solve by writing an equation . The answer to the problem must be 6
*September 20, 2010*

**statistics**

the amount of time spent in North American adults watching television per day is normal distributed with a mean of 6 hours and a standard deviation of 1.5 hours
*September 6, 2010*

**Zoology**

Can you rank these from the smallest to the largest? Heart carbon atom sodium atom electron nucleotide tundra mitochondria glucose molecule fungal cell hydrogen atom
*August 29, 2010*

**Algebra**

Determine whether the graphs of the equations are parallel lines, perpendicular lines, or neither. 12x + 4y = 16 5y - 22 = -15x
*May 7, 2010*

**Chemistry**

Ethanol is a fuel that can be made from corn. How many kJ of heat energy are released when 3.00 kg of ethanol are burned? C2H5OH(l) + 3O2(g) ¨ 2CO2(g) + 3H2O(g) H = -1406.8 kJ/mol
*April 17, 2010*

**calculus**

Use an appropriate local linear approximation to estimate the value of Cotangent 46 degrees.
*April 14, 2010*

**computer science**

write a program that asks the user to enter today's sales rounded to the nearest $100 for each of three stores. the program should then display a bar graph comparing each store's sales. create each bar in the graph by displaying a row of astericks. each asterick should...
*April 5, 2010*

**grammar**

How do I know what the simple subject of the sentence is and the complete subject?
*March 25, 2010*

**social studies**

what effect did california's rapid population growth have on californios and native americans
*March 8, 2010*