Saturday

December 10, 2016
Total # Posts: 726

**chemistry**

Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars everyday. Although the actual process also requires water, a simplified equation (with rust shown as iron(III) oxide (Fe2O3) is: 4Fe(s)+3O2(g) --> 2Fe2O3(s) ...

*October 13, 2015*

**chemistry**

Dr. Bob.. 630.24 kj was marked wrong...it said hint: make sure to carry out dimensional analysis........ ÄH value refers to the amounts of (moles) of substances and their matter in that specific equation. help....please....

*October 13, 2015*

**chemistry**

Consider the following balanced thermochemical equation for a reaction sometimes used for H2S production: 1/8 S8 (s) + H2 (g) ¨ H2S (g) ƒ¢Hrxn = -20.2 kJ (a)Is this an exothermic or endothermic reaction? (b)What is ƒ¢Hrxn for the reverse reaction...

*October 13, 2015*

**chemistry**

A 49.3 g sample of ethylene glycol, a car radiator coolant, loses 624. J of heat. What was the initial temperature of ethylene glycol if the final temperature is 32.5°C (c of ethylene glycol = 2.42 J/gK)? 624= 49.3 x 2.42(T-32.50) T = 37.73 = 38degrees is this correct? ...

*October 13, 2015*

**chemistry**

What is the (H3O+) and the ph of a buffer that consists of 0.25M HNO2 and 0.69M KNO2? (Ka of HNO2 = 7.1 x 10^-4) is this right? pH of acidic buffer pH = pka + log(salt/acid) pka = -log ka = -log(7.1*10^(-4)) = 3.15 = 3.15+log(0.25/0.69) pH = 2.71 [H3O+] = 10^-pH = 10^(-2.71...

*October 9, 2015*

**Math**

2.0

*October 8, 2015*

**Math**

A bakery used 4 cups of flour to make a full size cake. If they wanted to make a cake that was 0.5 the size, how many cups of water would they need.

*October 8, 2015*

**Math**

I apologize about this question I meant to send a different

*October 8, 2015*

**Math**

On Halloween 2 friends received 0.1 of a pound of candy. How much candy did they receive total?

*October 8, 2015*

**math correction**

correction what is : 1 x 10^-14 / 2.54 x 10^-3 the x's are (times) not variables thank you.

*October 5, 2015*

**math**

what is 1 x 10-14 / 2.54 x 10 -3 the x's are times not variables. I need the answer in scientific notation

*October 5, 2015*

**chemistry**

excited state

*October 5, 2015*

**chemistry**

The weak acid HQ has pKa of 4.89. Calculate the (OH-) of 0.500 M HQ This is what I have: pKa = 4.89 so Ka = 10^-4.89 = 1.29x10^-5 Ka = 1.29x10^-5 = [H+][Q-] / [HQ] 1.29x10^-5 = x^2 / 0.046 - x x^2 + 1.29x10^-5x - 5.93x10^-7 = 0 x = [H+] = 7.64x10^-4M pH = -log[H+] = 3.12 1....

*October 4, 2015*

**chemistry**

The weak acid HQ has pKa of 4.89. 1)Calculate the [H3O+] of .035 M HQ. 2)Calculate the (OH-) of 0.500 M HQ ....Am I correct? a) pKa = 4.89 => - log(Ka) = 4.89 => Ka = antilog(- 4.89) = 10-4.89 = 1.29x10-5 1. Given concentration of HQ, C = 0.035 M Dissociation of HQ is ...

*October 4, 2015*

**ap chemistry**

The weak acid HQ has pKa of 4.89. 1)Calculate the [H3O+] of .035 M HQ. 2)Calculate the (OH-) of 0.500 M HQ ....Am I correct? a) pKa = 4.89 => - log(Ka) = 4.89 => Ka = antilog(- 4.89) = 10-4.89 = 1.29x10-5 1. Given concentration of HQ, C = 0.035 M Dissociation of HQ is ...

*October 4, 2015*

**chemistry**

acetylsalicylic acid (aspirin) HC9H7O4 is the most widely used pain reliever and fever reducer. Find the PH of 0.040 M aqueous aspirin at body temperature (Ka at 37 C = 3.6 x 10-4) is this correct? initial concentration is 0.040 M. let change in concentration to equilibrium ...

*October 4, 2015*

**chemistry**

How many moles of H3O+ or OH- must you add per liter of HA solution to adjust its pH from 9.75 to 9.01? Assume a negligible volume change. ……….x 10………Moles of ……………………..h3O+ or OH- I got 4.6001 x 10-5 M of ...

*October 4, 2015*

**chemsitry **

acetylsalicylic acid (aspirin) HC9H7O4 is the most widely used pain reliever and fever reducer. Find the PH of 0.040 M aqueous aspirin at body temperature (Ka at 37 C = 3.6 x 10-4) is this correct? initial concentration is 0.040 M. let change in concentration to equilibrium ...

*October 4, 2015*

**chemistry**

How many moles of H3O+ or OH- must you add per liter of HA solution to adjust its pH from 9.75 to 9.01? Assume a negligible volume change. ……….x 10………Moles of ……………………..h3O+ or OH- I got 4.6001 x 10-5 M of ...

*October 4, 2015*

** chemistry**

Codeine (C18H21NO3) is a narcotic pain reliever that forms a salt with HCl. What is the pH of 0.064 M codeine hydrochloride (pKb of codeine is 5.80)? Thank you.

*October 2, 2015*

**AP Chemistry**

I am fairly sure that a) is no change, and c) is shifts to the right...but I am not sure about b) and d). Thanks. How does the equilibrium position shift as a result of each of the following disturbances? Sodium bicarbonate undergoes thermal decomposition according to the ...

*October 1, 2015*

**chemsitry**

1)Balance the following gas-phase reaction and 2) write its reaction quotient, Qc: CH4(g)+F2(g)......>>.....<<....... CF4(g)+HF(g) Include the physical states of all reactants and products in your balanced equation. Qc=

*September 29, 2015*

**Chemistry**

I was doing a lab experiment on the reaction of copper(II) sulphate and aluminum: 1) I measured 2.02g of copper(II) sulphate pentahydrate 2) I dissolved the copper(II) sulphate pentahydrate in 10mL of distilled water 3) I added 2.0mL of concentrated HCl to the solution and ...

*September 26, 2015*

**Chemistry**

I was doing a lab experiment: 1) I measured 2.02g of copper(II) sulphate pentahydrate 2) I dissolved the copper(II) sulphate pentahydrate in 10mL of distilled water 3) I added 2.0mL of concentrated HCl to the solution and mixed well 4) I added 0.25g on Aluminun foil to the ...

*September 26, 2015*

**CBU**

I was doing a lab experiment on the reaction of copper(II) sulphate and aluminum: 1) I measured 2.02g of copper(II) sulphate pentahydrate 2) I dissolved the copper(II) sulphate pentahydrate in 10mL of distilled water 3) I added 2.0mL of concentrated HCl to the solution and ...

*September 26, 2015*

**CBU**

How to calculate moles in a sample

*September 26, 2015*

**math**

Allison and Fred both work at the mall., but Allsion make $2 more than Fred. They work equal hours. Let x represent Allison earnings and y to represent Fred earnngs. Draw a graph representing the relationship between Allison and Fred earnings.

*September 21, 2015*

**Math**

combine like terms. 14 + 5x + 15 - 7x 29 - 2x

*September 21, 2015*

**chemistry**

Assume water boils at 100.0 C in Houston(near sea level) and at 90.0 C in Cripple Creek Colorado(near 9, 500 feet). If it takes 4.7 min to cook an egg in Cripple Creek and 4.4 min in Houston, what is Ea for this process? Enter your answer in scientific notation. Thanks.

*September 14, 2015*

**chemistry**

Assume water boils at 100.0 C in Houston(near sea level) and at 90.0 C in Cripple Creek Colorado(near 9, 500 feet). If it takes 4.7 min to cook an egg in Cripple Creek and 4.4 min in Houston, what is Ea for this process? Enter your answer in scientific notation. Thanks.

*September 14, 2015*

**science**

. Three charges are positioned as indicated in the figure. Calculate net force exerted on the +15 µC charge by the +11 µC and +13 µC charges

*September 2, 2015*

**Physics**

A 480 N man is standing on a 120 N pole supported by 2 blocks. The pole is 6 m long. One block is at the end while the other is 2 m away from the center. Where should the 480 N man stand?

*July 12, 2015*

**Life orientation**

Evaluate the extent to which the service delivery protes of water met or didi not met the rquirements of processes that you have to reseached

*May 16, 2015*

**Communication in the Workplace**

an outline for the letter would be nice

*April 15, 2015*

**Communication in the Workplace**

Imagine that you have taken a new job as head of Human Relations (HR) for an up-and-coming software firm. Your 150 employees are hip, smart and tech savvy. They are also big cell phone users. Cell phones are an important tool for your business communications, and you don't...

*April 15, 2015*

**physics**

Calculate the coefficient of kinetic friction for tyre rubber on the road surface.

*April 2, 2015*

**CDA**

I think D

*March 21, 2015*

**English check**

I agree with a

*March 21, 2015*

**Physics**

Two horizontal forces Upper F1 Baseline and F2 act on a 3.6 kg disk that slides over frictionless ice, on which an xy coordinate system is laid out. Force F1 is in the positive x direction and has a magnitude of 7.1 N. Force F2 has a magnitude of 9.3 N. The figure here gives ...

*March 15, 2015*

**math**

write 1.5 billion as a standard numeral

*March 10, 2015*

**religion**

"The Will to Believe," contains William James' response to Clifford. You are to write 200-300 words explaining James' response to Clifford's position. Be sure to include the following: 1. Explain James classification of hypotheses as alive or dead and the...

*February 26, 2015*

**Science:Physics**

Nilo drives is van with an average velocity of 45.0 km/h along the North Expressway. How long will it take him to drive 350 km on a perfectly straight highway

*January 30, 2015*

**Accounting**

Jay Pembroke started a business. During the first month (April 20--), the following transactions occurred. Invested cash in business, $18,428. Bought office supplies for $4,433: $1,896 in cash and $2,537 on account. Paid one-year insurance premium, $1,003. Earned revenues ...

*January 22, 2015*

**statistics**

1. On the basis of past experience, the buyer for a large sports store estimates that the number of 10-speed bicycles sole next year will be somewhere between 40 and 90 – with the following distribution: Number of Bicycles Sold x Probability P(x) 40 0.05 50 0.15 60 0.41 ...

*January 22, 2015*

**Science**

Why are phosphates rocks useful?

*January 14, 2015*

**physics**

how much heat is needed to raise the temperature of 5kg of silver from 20 degrees C to 96 decgrees C?

*January 12, 2015*

**Calculus**

An aquarium is to be constructed to hold 2160 in3. The base is to made of slate and the sides of glass. If slate costs 5 times as much as the glass per sq in, find the dimensions that will minimize the cost of constructing the aquarium. I started going about this problem by ...

*November 28, 2014*

**CHEMISTRY **

how can different steps in the analytical process help in solving probs in Analytical Chemistry

*November 26, 2014*

**english**

All of the following compound nouns are correct except a.editors in chief. b.sons-in-law. c.bird watchers. d.mother-in-laws. I am think a

*November 19, 2014*

**math**

Janet bakes a cake in the shape of a cube with side length x (in inches). She makes a vertical cut parallel to one of the sides, resulting in a slice with width y where x is 5 times as large as y. a) Define a function h that determines the volume of the cake before Janet makes...

*October 8, 2014*

**Physics**

Initial speed = 28m/s time = 4.4s Acceleration = 9.8 Just plugin the numbers into this formula and u will get the answer. S=ut+1/2*a*t^2

*October 8, 2014*

**CHECK PLEASE**

abscond : flee :: A. ascertain : forget B. concise : cut C. discern : hide D. abhor : detest

*September 22, 2014*

**statistics **

The mean sleep time of babies is 14hrs,a sample of 64 babies showed a mean of 13hrs 30min with a standard deviation of 3hrs at 1% level of significance. Test the assertion that the mean sleep of the babies is less than 14hrs a day.

*August 7, 2014*

**statistics **

The mean lifetime of a sample of 100 light tubes is 1570 hours with a standard deviation of 80 hours test the hypothesis that the mean lifetime of the tubes is 1600 hours

*August 7, 2014*

**Calculus Help Please Urgent!!!**

A cone-shaped paper drinking cup is to be made to hold 30 cm^3 of water. Find the height and radius of the cup that will use the smallest amount of paper. (Round your answers to two decimal places.) Height = ? Radius = ? Show work please!!!

*April 15, 2014*

**CHEMISTRY HELP !!!! **

the following statement is false. Rewrite that it makes a correct statement about free energy. a. ΔGuniverse > 0 for any spontaneous process.

*April 15, 2014*

**CHEMISTRY HELP !!!! Show work please!**

Compute the energy released in kilojoules when the sun converts 1.00 metric ton into energy. NOTE: 1 metric ton = 1000 kg.

*April 14, 2014*

**math**

77.5

*April 8, 2014*

**Math (Trigonometry)**

1. If sec x + tan x = 3/2 and 0 ≤ x ≤ pi/2 then the value of sin x is... 2. If 0 ≤ x ≤ pi/2 and tan²x + sec x = 5 then cos x = ... Please help

*April 6, 2014*

**Physics**

The seesaw in the figure below is 4.5 m long. Its mass of 20 kg is uniformly distributed. The child on the left end has a mass of 14 kg and is a distance of 1.4 m from the pivot point while a second child of mass 39 kg stands a distance L from the pivot point, keeping the ...

*March 28, 2014*

**Statistics**

An economist found that a random sample of 42 high school teachers had an average annual salary of $56,490. A previous study showed that the population standard deviation is $4150. Calculate the margin of error, E, for a 99% confidence interval for µ, the average annual ...

*March 1, 2014*

**bergen community college**

210cm

*November 8, 2013*

**chemistry**

A 47kg sample of water absorbs 3.40×10^2kJ of heat. Part A If the water was initially at 21.5∘C, what is its final temperature?

*September 15, 2013*

**chemistry**

Gold has a density of 19.3 g/cm3. Do you think you could carry 1.30 cubic ft (rhetorical--don't answer)? How many pounds does 1.30 cubic feet of gold weigh? [453.6 g = 1 lb, 2.54 cm = 1 in, and 1 ft = 12 in.]

*September 14, 2013*

**Math: Algebra**

800

*September 10, 2013*

**Calculus**

The equation of motion of a particle is s=4t^3−7t, where s is in meters and t is in seconds. Find a) the velocity of the particle as a function of t : v(t)= b) the acceleration of the particle as a function of t : a(t)= c) the velocity after 5 seconds d) the acceleration...

*June 13, 2013*

**Math **

Im thinking of a two-digit number. It is a prime number which is 3 less than a perfect square. Also, when it's digits are reversed, it becomes a perfect square. What is the one possible number?

*June 11, 2013*

**geometry**

45. Find the similarity ratio of a cube with a volume 512 m3 to a cube with volume 3,375 m3. (1 point) 8 : 15 64 : 225 15 : 8 225 : 64

*June 10, 2013*

**Geometry**

help please

*June 10, 2013*

**Geometry**

44. The volume of a sphere is 2,098 m3. What is the surface area of the sphere to the nearest tenth? (1 point) 1,700 m2 146.2 m2 850 m2 26,364 m2

*June 10, 2013*

**us history**

Ms. Sue, trying to figur out how to even break down the question? Thanks, Patrick

*May 4, 2013*

**us history**

3. Keeping in mind how the expansion of U.S. territory westward threatened the delicate balance of power in Congress between free and slave states and Lincoln’s stance on slavery, describe how key events (such as land acquisitions, agreements about how new territories ...

*May 4, 2013*

**History**

2. The new democratic age of the 1820s, ’30s, and ’40s not only witnessed the advent of universal white male suffrage but also a strong impulse for social reform, which was often supported by those denied access to the ballot. What drove the impulse behind such ...

*May 4, 2013*

**maths**

When pulled a 30 m piece of string streches 180cm.find percentage increasing length

*April 22, 2013*

**govenment**

a, c, and d

*March 28, 2013*

**Chemistry**

How do you write a chemical equation for NH4NO3? Is it... NH3 + H2O= NH4 + OH

*March 19, 2013*

**Physics**

I am having a problem answering a physics question: A plane is heading due south and climbing at the rate of 60 km/hr. If its airspeed is 540 km/hr and there is a wind blowing 110 km/hr to the northwest, what is the ground speed of the plane?

*March 17, 2013*

**Chemistry**

Suppose 50.00 mL of 2.0 E -5 M Fe(NO3)3 is added to 50.00ml of 2.0 E -4M KIO3. Which of the following statements is true? For Fe(IO3)3, Ksp= 1.0 E-14 a-precipate forms because Qc<Ksp b-No precipate forms because Qc>Ksp c-Nothing happended d-No precipate forms because Qc&...

*March 17, 2013*

**Chemistry**

I figured out the answer. Thanks.

*March 17, 2013*

**Chemistry**

What is the solubility (in g/L) of PbCl2 at 25 degree celsius? The solubility product of PbCl2 at 25 degrees celcius is 1.6x10-5.

*March 17, 2013*

**chemistry**

How many electrons in a cesium atom can have the quantum numbers of n = 3 and ml = -1

*March 9, 2013*

**maths help please**

9409

*February 27, 2013*

**Chemistry**

Question asking about how enzymes affect the rate of a reaction. Check all that apply 1. They shift the reaction equilibrium towards the products. 2. They increase the concentration of the reactants. 3. They lower the activation energy of the reaction. 4. They decrease the ...

*February 20, 2013*

**Physics**

Two blocks sit on a horizontal surface. They are connected to each other by a massless cord. The block on the left has a mass of 4.8 kg and the block on the right has a mass of 2.2 kg. Another massless cord is attached to the block on the right and pulls that block with a ...

*February 18, 2013*

**Physics**

A thin 5.4-m metal rod sustanins a longitudinal standing wave with vibration antinodes at each end of the rod. There are no other antinodes. The density and Young's modulus of this metal are, respectively, 5200 kg/m^3 and 7.9x10^10 N/m2. What is the frequency of the rod&#...

*February 11, 2013*

**physic**

A canon is angled at 45º and fires a canon ball at 100 m/s. How long will it take the canon to reach it's maximum height?

*February 4, 2013*

**physic**

A canon is angled at 45º and fires a canon ball at 100 m/s. How long will it take the canon to reach it's maximum height?

*February 4, 2013*

**Chemistry**

Which ligand binds the tightest? Ligand A, with a Kd of 10^-9M Ligand B, with a Kd of 10^-3M Ligand C, with a percent occupancy of 30% at one micromolar Ligand D, with a percent occupancy of 80% at 10 nm

*January 31, 2013*

**Chemistry**

I'm given sequences and asked to classify them as "Most likely an amphipathic alpha helix", "Most likely an amphipathic beta sheet", "Most likely a turn/loop" or "Not Amphipathic" Sequence 1: Arg-Phe-Gln-Ile-His-Val-Gln-Phe-Glu ...

*January 29, 2013*

**Math**

HELP! Input:1 1/3 Output 7/12 Input 2 3/5 Output 1 17/20 Input 3 5/6 Output ? Input ? Output 3 5/8. What is the rule, and what are the question marks values?

*January 23, 2013*

**Physics**

A long jumper leaves the ground at an angle of 15.1◦ to the horizontal and at a speed of 10.9 m/s. How far does he jump? The acceleration due to gravity is 9.8 m/s2 . Answer in units of m 010 (part 2 of 2) 10.0 points What maximum height does he reach? Answer in units of m

*January 23, 2013*

**chemistry**

23 grams of NaOH is dissolved in 1.5L of water, find; a)Concentration of the solution b)pOH c)pH

*January 20, 2013*

**chemistry**

A chemist decomposes several samples of carbon monoxide into carbon and oxygen and weighs the resultant elements. The results are shown below: Sample Mass of Carbon Mass of Oxygen 1 6 8 2 12 16 3 18 24 Do you notice a pattern in these results? Next, the chemist decomposes ...

*January 13, 2013*

**Physics**

Find the work done in stretching the spring. Answer in units of J

*December 14, 2012*

**Physics**

The force required to stretch a Hooke’s-law spring varies from 0 N to 70.4 N as we stretch the spring by moving one end 5.35 cm from its unstressed position. Find the force constant of the spring. Answer in units of N/m

*December 14, 2012*

**physics**

A 22 g bullet is accelerated in a rifle barrel 43.2 cm long to a speed of 907 m/s. Use the work-energy theorem to find the average force exerted on the bullet while it is being accelerated. Answer in units of N

*December 14, 2012*

** math 5th grade**

Lynda cut 3.2 meters of ribbon into equal-size pieces. Each piece was longer than .01 meter, but shorter than .02 meters, with lengths in increments of .02 meters. How many pieces did Lynda cut and how long was each piece?

*December 12, 2012*

**Chemistry 12**

given the reacting system: H2 (G) + I2(G) ---> 2HI(g) Keq= 64 Equal moles of H2, I2, and HI are placed in a 1.0 L container. Use calculations to determine the direction the reaction will proceed in order to reach equilibirum

*December 6, 2012*

**Chemistry 12**

given the reacting system: H2 (G) + I2(G) ---> 2HI(g) Keq= 64 Equal moles of H2, I2, and HI are placed in a 1.0 L container. Use calculations to determine the direction the reaction will proceed in order to reach equilibirum

*December 6, 2012*