Saturday

April 30, 2016
Total # Posts: 765

**Chemistry**

The triprotic acid H3A has ionization constants of Ka1 = 6.8× 10–3, Ka2 = 8.1× 10–9, and Ka3 = 5.0× 10–12. Calculate the following values for a 0.0760 M solution of NaH2A [H+] = ? [H2A-]/[H3A]= ? Calculate the following values for a 0.0760 M ...
*February 26, 2013*

**Chemistry**

Phosphoric acid, H3PO4(aq), is a triprotic acid, meaning that one molecule of the acid has three acidic protons. Estimate the pH, and the concentrations of all species in a 0.100 M phosphoric acid solution. pKa1 = 2.16 pKa2 = 7.21 pKa3 = 12.32 [H3PO4] = ? [H2PO4-] = ? [HPO42...
*February 26, 2013*

**Chemistry**

What fraction of piperazine (perhydro-1,4-diazine) is in each of its three forms (H2A, HA–, A2–) at pH 7.22?
*February 26, 2013*

**Chemistry**

A certain indicator, HA, has a Ka value of 1.3 × 10-6. The protonated form of the indicator is blue and the ionized form is red. What is the pKa of the indicator? What is the color of this indicator in a solution with pH = 8? Blue, red, or purple?
*February 26, 2013*

**Chemistry**

This question has been bugging me for a long time. A rock contains a Pb-206 to U-238 mass ratio of .145 to 1.00. Assuming that it did not contain any Pb-206 at the beginning of its formation, determine its age. I assume from the other problems in my book that the 1/2 life is 4...
*February 23, 2013*

**chemistry**

However, when I try to find the rate constant I get 3.5. My book says 3.5^-.5. I don't know how they got this. .0069= (.010)^.5(.020)=approx 3.5 but the book says 3.5M^-1/2*s-1 Also I am wondering if there are three reactants in a problem, is there any difference how it is...
*February 23, 2013*

**chemistry**

I have a problem like this: CHCl3 + Cl2 = CCl4 +HCL This is the rate table: CHCL3 Cl2 Initial Rate .010 .010 .0035 .020 .010 .0069 .020 .020 .0098 .040 .040 .027 They want me to find the rate constant and the rate law.
*February 23, 2013*

**math**

1/72
*February 13, 2013*

**Math**

At a summer camp, one boy and one girl will be selected to lead the weekly activities. If there are 130 boys and 145 girls at the camp, how many different 2 person combinations of 1 boy and 1 girl are possible?
*February 5, 2013*

**Math**

On friday, a computer was priced at $800. on the following wednesday, the price was reduced by 15%. On the following friday, the price was further reduced by 20%. what percent of the original price was the final price ?
*February 5, 2013*

**Chemistry**

180
*January 29, 2013*

**Chemistry (Biochem)**

The true answers are 1,2 and 7. If the residues are polar then it only makes sense for them to come into contact with the solvent, as they are the hydrophilic amino acids.
*January 27, 2013*

**english**

The reason your voice matters is because its part of the way you want to be respected, spoken to, as well as you are part of a family of individuals. The fact that you have ideas of your own and you have values and an opinion is also why your voice should be heard. You have ...
*January 8, 2013*

**geometry**

LPG is stored in highly insulated spherical vessels in most oil refineriesif.If the inside diameter of one of these tanks is 11.4ft, find it's volume. Report your answer to the nearest one-tenth of a gal. Use r=3.14 and 1 cubic ft=7.5gal
*December 29, 2012*

**geometry**

find the volume of an industrial tank in the form of a horizontal cylinder whose radius is 2.6 yd, and whose length is 8.4 yd. rr=3.14
*December 29, 2012*

**chemistry**

When compound A is heated with acid compound B forms. Ahas the formula C3H8O and B is C3H6. When Ais oxidized compound D forms that is further oxidized to carboxylic acid. What are compounds A, B, and C.
*December 17, 2012*

**chemistry**

What is the pH of a solution prepared by dissolving 1.533 g HCl in water to make 420 mL of solution
*December 17, 2012*

**biology**

Following the usual pathway of circulation blood flows from the __________ to ___________, to_____________and to__________
*December 14, 2012*

**biology**

The ___________ ____________ supplies blood from the heart to all organs except the lungs
*December 14, 2012*

**biology**

Terms like punctiform and round relate to colonial ____________while smooth and curled relate to colonial___________
*December 14, 2012*

**biology**

Traditional phylogenetic results have been challenged by the results of _________________
*December 14, 2012*

**pre-algebra**

the perimeter of a pool is 150m. the width is 1/2 its length. what are the dimensions of the pool
*December 13, 2012*

**Chemisrty**

A 10.0 g sample of ice at -14.0°C is mixed with 124.0 g of water at 81.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J/g°C, respectively, and the enthalpy of...
*December 9, 2012*

**Accounting**

Harris company borrowed 65,000 by giving 10 year , 6% installment note to Cuba Bank The note requires annual payments of $8832 first payment occuring on the last day of the fiscal year. the first payment consists of interest of $3,900 and principal repayment of $4932, Issued ...
*December 6, 2012*

**Psychology**

the spillover effect is best explained in terms of the?
*November 17, 2012*

**nuclear chemistry**

wouldn't you divide by the speed of light squared? nuclear chemistry - andrew, Saturday, November 10, 2012 at 8:26pm E=mc^2 10^6 J/s are being produced (1Mw) 10^6 J/s = m (3.0e8 m/s) solve for mass to find amount of mass lost in one second. ~ .0033kg
*November 10, 2012*

**nuclear chemistry**

A typical nuclear reactor produces 1mw of power per day. What is the minimum rate of mass loss required to produce this energy. Don't know where to start
*November 10, 2012*

**chemistry**

never mind I got it thanks!
*November 8, 2012*

**chemistry**

This all that I have, what other information do I need?
*November 8, 2012*

**chemistry**

I need help with this lab. Write the equation for the decomposition of the hydrate, CuSO4*XH2O. Mass of crucible and hydrate: 93.000g Mass of crucible and pure salt: 91.196g I need to calculate the following: 1. mass of water in hydrate sample(g) 2. number of moles of water ...
*November 8, 2012*

**math**

Ashley needs $30 more in order to buy a concert ticket. she has saved money from her birthday and christmas presents. Her b-day present was 1.5 times the amount of her christmas present. Her b-day present was $60. if she saved 80% of her presents, how much does the concert ...
*November 6, 2012*

**math**

if 2 small containers and 1 large container together hold 10 cups of water, and 1 large container minus 1 small container leaves 4 cups of water, how many cups of water does the large container hold.
*November 6, 2012*

**Business Math**

Hafers, an electrical supply company, sold $4,800, 12%, 90-day note for a time extension of a bill for goods bought by Ron Prentice. On June 12, Scott discounted the note at Able Bank at 10%. What is the Maturity Value (MV).
*November 6, 2012*

**psychology**

For finals week, you had to be prepared for exams in english,math,spanish,italian,and history. how should the sequence of study be arranged to minimize the possibility of interference
*October 26, 2012*

**math**

3 out of 5 students own a pet. 6 out of 11 students own a pet. are the results proportional? explain reasoning
*October 23, 2012*

**Chemistry**

A vessel containing air (79% N2 and 21% O2) at 5bar and 280K is placed in a vacuum and a tiny hole is punched through the lid of the vessel. If the rate of effusion of O2 is 1.25x10^-7mol/s, at what rate is the nitrogen effusing? (in mol/s)
*October 4, 2012*

**math**

the hardware store is 5 blocks east of john's house. sean lives 3 blocks west of the bank, which is 4 blocks south and 2 blocks west of the hardware store. how many blocks and in what direction is sean's house from john's house?
*October 1, 2012*

**math**

the perimeter of rectangle y is equal to its area. rectangle z has the same perimeter as rectangle y. The length of rectangle z is 5 inches and the width is 3 inches. Explain how you can find the length and width of rectangle y.
*September 25, 2012*

**Physics**

You throw a ball downward from a window at a speed of 2.7 m/s. How fast will it be moving when it hits the sidewalk 2.9 m below?
*September 18, 2012*

**Chemistry- rate laws**

CH3CHO decomposes into methane gas and carbon monoxide gas. This is a 2nd order reaction. Rate of decomposition at 140 degrees Celsius is .10M/s when the concentration of CH3CHO is .010. What is the rate of the reaction when the concentration of CH3CHO is .50M? Have not been ...
*September 18, 2012*

**math**

1-How many three digit numbers are even? 2-how many three digit numbers are not even and do not divide by 5 ?
*September 16, 2012*

**math**

How many three-digit numbers are even ?
*September 16, 2012*

**math**

How many four-digit numbers divide by 5 ? Note:0001 is considered a 1-digit number .
*September 16, 2012*

**math**

Suppose a license plate requires three letters ,followed by three digits.how many license plates are there if the letters are all different and the digits are all different
*September 16, 2012*

**chemistry**

Determine the final temperature when 10g of steam at 100C mixes with 500g of water at 25C. I have 4.184x 10(100-x) + 40700 x 10= 500 x (x-25) x 4.18. The book has 10/18 instead of 10 on left hand side of equation. Why??
*August 18, 2012*

**chemistry**

Find the number of disintegrations per minute emitted by 1.1 mol of 232-Th in 1 min. The half-life of 232-Th is 1.4 x 1010 year I was able to do this with the following technique: 1.1 x 6.022 x10^23 =6.62x10^23 1.4x10^10=7.358x10^15 minutes I think then it is 6.62x10^23 x 7....
*August 2, 2012*

**algebra/logs**

I don't understand this problem: (1/2)n = 0.015625 n log 0.5 = log 0.015625 n = log 0.5 / log 0.015625 n = 6 When I plug log .5 into the calculator it gives .3010 and when I plug .15625 to the calculator it is -1.806 and that would be -.3010/-1.806 =.1666. How is the ...
*August 2, 2012*

**algebra**

solve the equation 5x^2=19x+4 X=
*July 24, 2012*

**algebra**

Find the number of decibels for the power of the sound. round to the nearest decibel. A rock concert, 5.35x 10^4 watts/cm^2
*July 24, 2012*

**chemistry**

I think I've got it by looking through the balanced equation. It is just hard to understand the NA repeated twice on the right side of the equation.
*July 1, 2012*

**chemistry**

you are right. It is Na2HPO4 + HI ==> NaI + NaH2PO4 for which the net ionic equation is HPO4^- + H^+ ==> H2PO4^- Can you explain how to get this, though? any steps would be helpful.
*July 1, 2012*

**chemistry**

I need to derive a net ionic equation after balancing: NA2PO4 (2-) +HI =? what I have so far is NA2Po4 +2HI = 2NAI +H3PO4 I can't get any farther but the answer is HPO4 (2-) +H =H2PO4 can someone help me with the steps?
*July 1, 2012*

**finance**

BBA307: Finance Exercise 8A Assignment 8.1 Assignment 8.1: Capital Budgeting Application You have just graduated and one of your favorite courses was Financial Management. While you were in school, your grandfather died and left you $1 million. You have decided to invest the ...
*June 28, 2012*

**geometry**

the arc length of AB is 2^pi ft. find the radius of the circle ABC=43 degree. round your answer to the nearest hundredth.
*June 25, 2012*

**Geometry**

I need help on a problem thats on formula for circumference. A circle has a circumference of 36 cm. find it's radius .but it says give an exact answer in simplest form and it says enter pi for the symbol of pie .
*June 22, 2012*

**chemistry**

You don't need to do a balanced equation for this one. 2.5x =.100(.50) x=.020 this would be 20 ml the formula is Liters x Molarity =Moles so 2.5Molar times x # of liters =.100 x.50 answer is 20ml
*June 19, 2012*

**chemistry**

molarity x liters = moles you would need to know how many moles or liters to use the above formula. How much NAOH are you being asked to find molarity for?
*June 18, 2012*

**Chemistry**

I don't know if I should be posting this on a new session or just the old one; I asked it yesterday and I have not seen a reply I have: the half life of U-238 is 4.5 x 10^9 yr. A sample of rock of mass 1.6g produces 29 disintegrations per second. find percent by mass of U-...
*June 18, 2012*

**math**

actually David is right. I forgot the decimal place from the 22 so it is 54.5 amps
*June 17, 2012*

**math**

E= I x R is the formula the answer is .5454 I=amperes R=ohms E=volts 12volts/22
*June 17, 2012*

**chemistry**

I have: the half life of U-238 is 4.5 x 10^9 yr. A sample of rock of mass 1.6g produces 29 disintegrations per second. find percent by mass of U-238 in rock. I have 4.5x 10^9x60x60x365x24=1.419x 10^17= .693/1.419 x10^17 =4.883x10^-18 =rate 1.6/238=.006722 x 6.022 x10^23=4.048 ...
*June 17, 2012*

**Chemistry**

2Na + 2H2O → H2 + 2NaOH is the balanced equation. from that, .113 mole/2=.0565 x -368 = -20.79kj or 20.79 kj heat is created in the reaction.
*June 17, 2012*

**chemistry**

Yes this does help! Thanks!
*June 17, 2012*

**chemistry**

A 1.50 liter gas sample at 745mm HG and 25 celsius contains 3.55% radon by volume radon-220 is an alpha emitter with a half life of 55.6 seconds. how many alpha particles are emitted in 5 minutes by this sample? I got an answer 1.59x10^19 I started at 745/760=.980263 then ....
*June 17, 2012*

**Chemistry**

X-rays have a wavelength in the range of 0.01 to 10 nanometers.. That would be a wavelength of up to 10 billions of a meter
*June 17, 2012*

**Algebra 2**

An ice-cream parlor sells sundaes with 3 different types of ice-cream and 4 different toppings. They have 8 flavors of ice-cream and 10 toppings for their customers to chose from. what is the probability that a customer orders a sundae including the toppings of whipped cream, ...
*May 24, 2012*

**math**

To turn a %number into a decimal just move the decimal over two spots from the whole number. So, for example 100% would be 1, or 33 1/3 would be .33333 which is 1/3 of 100%. The 1/3 part turns into .33 because 1/3 of a dollar is 0.33 cents. another example would be 25% is 0.25...
*May 22, 2012*

**chemistry**

Thank you Dr.Bob for your speedy reply-I also tutor in other subjects, but chem. is my nemesis.
*May 15, 2012*

**English**

"Spielberg's ability to communicate visually in the media of film is no doubt matched by his versatility as a public speaker." take it from there. giving examples of the oral topics he might cover as expressed already in his incredibly varied kinds of films, from...
*May 15, 2012*

**English 2 Animal Farm**

He simply represents a worldly point of view rooted in negativism based on experience (vs. the Intellect, the Evil, the populist)
*May 15, 2012*

**chemistry**

How many joules to vaporize 1.5 L of H2O at 19 degrees Celsius?
*May 15, 2012*

**English**

Note the individual words that have common associations:stagger, fall. note the repetition of vowel sounds within the lines to strengthen the mood.note how short the lines and words are, to mimic the nature of the scenery--harsh, barren, ie., tough.
*May 14, 2012*

**Biology**

I think that you calculate algebraically: since 400% is quadruple, divide that by 5.5% to get the # of years
*May 14, 2012*

**Algebra 2**

a hyperbola is centered at (3,7). The vertices are (9,7) and (-3,7). The slopes of the aymptotes are m==/-5/6. Enter the equation of the hyperbola in the form: (x-h)^2/a^2-(y-k)^2/b^2=1
*May 14, 2012*

**Algebra 2**

Soo the equation is 25y^2-9x^2-200y-36x+139=0 and for the center is got (2,4) and the vertices I got (2,7) and (2,1) But i cant figure out how to find the slopes of the asymptotes and it wants the answer is reduced fraction please explain
*May 13, 2012*

**Writing**

My own opinion on this issue is that it is past time for the government to take some responsibility in legislating the food products/garbage that is so heavily marketed through advertising--the detrimental effects of eating junk foods that lead to cancer, heart disease, ...
*May 12, 2012*

**chemistry**

I think that the base always contains hydroxide, aka OH; the original components were water mixed with an ammonium compound ( NH2)Check the chemistry reference tables too, which have tables that identify the bases and acids.
*May 12, 2012*

**poems**

Sammy sold seashells by the shoreline on oysters and mussels he did dine when the tide rolled in he went for a swim and forgot about selling those seashells
*May 12, 2012*

**Algebra 2**

A package with square ends has combined length and girth(girth is perimeter of a cross section) of 120 in. The surface area of the entire package is 3600 sq. in. Determine the dimensions of the package. s in. * s in.* l in. One solution is: 11.08in. * 11.08in. * 75.68in. Find ...
*April 29, 2012*

**Math**

a cylinder has a radius of r and a height of h. A rectangular box has a length of r, a width of h and height of h. Their combined volume is V=πr^2h+h^2r If their combined volume is 600 cubic inches and h is 5 inches, solve for the radius(r).
*April 29, 2012*

**Math**

the formula for the surface area of a cylinder is: A=2πrh+2πr^2 If the height of the cylinder is 10 inches, and the surface area is 200 sq. inches, determine the length of the radius
*April 29, 2012*

**Algebra **

The formula for the volume of a cylinder is: V=πr^2*h If the volume is 432 cubic inches and the height is 8 inches, solve for the length of the radius.
*April 29, 2012*

**algebra2**

If an object is thrown vertically upward with an initial velocity of v, from an original position of s, the height h at any time t is given by: h=-16t^2+vt+s (where h and s are in ft, t is in seconds and v is in ft/sec) Solve for t when the object hits the ground. (when h=0) t...
*April 27, 2012*

**Algebra 2**

If an object is thrown vertically upward with an initial velocity of v, from an original position of s, the height h at any time t is given by: h=-16t^2+vt+s (where h and s are in ft, t is in seconds and v is in ft/sec) If a rock is dropped from the top of a 200 ft building, ...
*April 27, 2012*

**Algebra 2**

A rectangular piece of cardboard has length that is 16 inches more than the width. The area of the cardboard is 297 sq. in. Find the measures of its width and length. Enter width in., length in.
*April 26, 2012*

**Algebra 2**

A farmer has 120 ft. of fencing available to enclose 2 adjacent rectangular pens alongside his barn. NO fencing is required along the bard side. He needs to have a total of 930 sq.ft. Determine the width (x) and the combined length of the pens. There are two solutions. One is ...
*April 24, 2012*

**Algebra 2**

√3x-4=2√x-5 Solve this equation, if there is more then one answer separate with a comma
*April 19, 2012*

**Algebra 2**

x= √3x+12+2
*April 18, 2012*

**Algebra 2**

√3x-4=2√x-5 Solve this equation, if there is more then one answer separate with a comma
*April 18, 2012*

**Algebra 2**

Solve this equation: √4x+8=6 If there is more then one solution enter with a comma
*April 18, 2012*

**algebra2**

evaluate without using a calculator 216 2/3
*April 18, 2012*

**Algebra 2**

SIMPLIFY: 3√(63x^5/(72y^6)) Example to enter answer: n√b, enter (b)^(1/n) Example: For 4√3:2, enter 4(2)^(1/3).What is my answer and how do i answer it?
*April 17, 2012*

**Pharmacology**

3/100
*April 16, 2012*

**algebra2**

How do i enter my answer? so the question is Simplify: √3:(63x^5/(72y^6)) and for my answer i got x√3:(7x^2/(2y^2)) but my work page says: Enter example: For 4√3:(2), enter 4(2)^(1/3) so how do i enter my answer
*April 14, 2012*

**math**

at a store you bought 2 pounds of apples and 1 1/3 pounds of grapes. If the store's scale measures to the nearest half pound, what is the range of possible actual weights for the sum of both purchases of fruits.
*April 13, 2012*

**how do i enter my answer**

√4:(32x^11y^15)/√4:(2x^3y^-2) for this equation i got =2x^2y^4√4:y and in my worksheet it says enter it: √b, enter sqrt(b). For example: For 4√3 enter 4sqrt(3) so how would i enter my answer
*April 13, 2012*

**Algebra 2**

√(21x^2y/(75xy^5) it says on my paper to enter it: √b, enter sqrt(b). For example: For 4√3 enter 4sqrt(3) Please help, I've got 5 wrong! :(
*April 13, 2012*

**Algebra 2**

An airplane flies 1050 km with the wind. In the same amount of time, it can fly 750 km against the wind. The speed of the plane in the still air is 200 km/h. Find the speed of the wind.
*April 12, 2012*