Science & Mathematics - 6 November 2007

Hello Yahoo Answers,
I need some help on the following question.


Calcium Carbonate reacts with hydrochloric acid to release carbon dioxide according to the following equation.

CaCO^3 + 2HCl = CO^2 + H^2O + CaCl^2

Atomic weights Ca = 40.1 , C = 12.0, O = 16.0 , Cl = 35.5 , H = 1.0

a. If 12.5 grams of calcium carbonate are mixed with an excess of acid calculate the moles of CO^2 formed.

b. Calculate the volume of CO^2 ( at STP) produced from the 12.5 grams of Clacium Carbonate.

c.If the 12.5 grams of CaCO^3 had been mixed with a volume of HCl such that the number of moles of HCl was 0.2 moles, calculate the moles of CO^2 formed



Any contribution will be appreciated.

Thankyou

2007-11-06 01:14:55 · 3 answers · asked by Anonymous in Chemistry

I seem to suck at calculus with trigonometric identities. Any suggestions?

2007-11-06 01:09:46 · 3 answers · asked by Anonymous in Mathematics

2007-11-06 01:08:55 · 7 answers · asked by Anonymous in Mathematics

If somebody has a 25% chance of a heart attack within the next 10 years, what are the chances of their having such an attack in any given year ? Am I right that the answer = 25/10 = 2.5 ? Or have I made a statistical gaffe ?

Would the probability change as the 10 years progressed ? If someone with a 25% chance in 10 years hasn't had an attack by the 9th year, would they be more at risk in the final year ? I'm inclined to say 'no' but might a different probability apply to a random year from a final year when nothing had happened so far ? Excuse me, please, if the question is statistically ignorant.

Btw : the person isn't me.

2007-11-06 01:08:12 · 1 answers · asked by Anonymous in Mathematics

2007-11-06 01:06:45 · 22 answers · asked by bob m 3 in Astronomy & Space

1) Aluminum nitrate + sodium hydroxide ----> Aluminum hydroxide + sodium nitrate

2) Potassium chlorate -----> pottasium chloride+ oxygen

3) Phosphoric acid+magnesium hydroxide -----> magnesium phosphate + water

2007-11-06 01:06:11 · 1 answers · asked by Caramel 2 in Chemistry

Hello Yahoo Answers,
I am having trouble with this Chemistry Question. Can I please have help?


N^2 + 3H^2 = 2NH^3 ALL substances are gaseous

Atomic weights N = 14, H = 1.0
a. How many moles of hydrogen gas would be required to react with 0.5 moles of nitrogen gas?

b. If 1.5 moles of nitrogen gas reacts with excess hydrogen calculate the mass of ammonia ( NH^3) produced.

c. If all gases were measured at the same temperature and pressure what would be the ratio of reacting volumes for
Nitrogen : Hydrogen : Ammonia
_______:_________:________





Any Contribution wil be apprciated.

Thankyou

2007-11-06 01:05:39 · 1 answers · asked by Anonymous in Chemistry

2007-11-06 01:01:53 · 4 answers · asked by joel p 1 in Medicine

I have seen a few different setups with a generator hooked up to a mechanical system like a stationary bike or a bike in a rack, etc. Whether the bike tire is pressed against the generator or a large flywheel was used the power output was limited to about 150 – 200 WATTS.

Taken the human component out of the equation, (I know that we have a biological limit as to how much horsepower we can transfer into the front end of the system), what limits the power output?

Increasing the RPM of the generator will increase the power output so why can’t the pedal system be geared up for higher RPM at the generator? (Were assuming that the generator has the capacity to generate more power than currently achieved).

There must be a logical reason that I just am not grasping at the moment otherwise someone would have already built this higher power pedal system.

The only thing I could think of is this is an issue of torque.

Having read many of the answers to dynamo questions I know there are some really helpful smart people out there and quite a few funny smart-alecs. Thank you to everyone who responds whether they are the former or the later.

Now for some coffee.

2007-11-06 00:57:30 · 1 answers · asked by caffine jag 4 in Physics

If possible, include an explanation.

2007-11-06 00:54:42 · 1 answers · asked by go_master 1 in Chemistry

An elevator cable breaks when a 795 kg elevator is 26.3 m above the top of a huge spring (k = 8.00 104 N/m) at the bottom of the shaft.

(a) Calculate the work done by gravity on the elevator before it hits the spring.

(b) Calculate the speed of the elevator just before striking the spring.

(c) Calculate the amount the spring compresses (note that here work is done by both the spring and gravity).

2007-11-06 00:52:16 · 2 answers · asked by Anonymous in Physics

Where did rock come from in the universe? And also ice because to make a planet lots of dust,rock and gas must collect together but if in the beginning there was nothingness, where did rock,dust and gas appear from it didnt just "happen"

My personal opinion is that we were created by someone or something but they dont know we exist because we are so small and insignificant, like inside of an atom or a higgs bosons particle.......but that then leads to another question where did they come from? (the "people" who made us)

2007-11-06 00:44:06 · 7 answers · asked by Anonymous in Physics

Let "u" and "v" be two non-negative numbers, whose sum is 10. Find the maximum value of "u^2*v". Determine "u" and "v" when the maximum is attained.

2007-11-06 00:42:57 · 4 answers · asked by bradm_127 1 in Mathematics

it's for our science project.. and i'm really an enviromentalist. so please do help=)

2007-11-06 00:37:31 · 2 answers · asked by natalie999 1 in Chemistry

I have 50 problems but 2 have stumped me umm they are 3x^2-11x-4 and 8x^2+2x+3

2007-11-06 00:34:32 · 7 answers · asked by Anonymous in Mathematics

the eqpt. is intransigently safe

2007-11-06 00:32:06 · 2 answers · asked by lionel g 1 in Engineering

2007-11-06 00:31:36 · 33 answers · asked by bob m 3 in Astronomy & Space

suppose that * is an associative and commulative binary operations on a set S, show that H = {a element s such that a * a = a} is closed under *

* means asteris as the binary operation...

2007-11-06 00:19:51 · 1 answers · asked by Anonymous in Mathematics

2007-11-06 00:18:40 · 2 answers · asked by aena q 1 in Zoology

....when I can't see anything when I look directly at it?

2007-11-06 00:18:17 · 5 answers · asked by insomnia c 4 in Physics

2007-11-06 00:16:50 · 2 answers · asked by Baby Gurl 1 in Chemistry

1. f(x)=x^2-5x+6
2. f(x)=x^2-10x+21
3. f(x)=x^2-x-6
4. f(x)=x^2-2x+4
5. f(x)=2x^2-x+6
6. f(x)=6x^2-x+2
7. f(x)=x^2+4x-5
8. f(x)=2x^2+2x-4
9. f(x)= -x^2+4x-3
10. f(x)= -x^2-5x-3
pls answer with complete solution...

2007-11-06 00:15:31 · 4 answers · asked by Anonymous in Mathematics

suppose that * is an associative and commulative binary operations on a set S, show that H = {a element s such that a * a = a} is closed under *

* means asteris as the binary operation...

2007-11-06 00:14:09 · 3 answers · asked by Anonymous in Mathematics

list out the diseases or disorders that are treated either partially or completely by neem
say also the various forms in which neem is used ie,,, the names of drugs that contain neem minimally or completely.
list out atleast 15 to20 drugs and diseases.

2007-11-06 00:11:50 · 6 answers · asked by Anonymous in Medicine