Science & Mathematics - 11 December 2007

2007-12-11 06:57:05 · 7 answers · asked by Anonymous in Astronomy & Space

We did an experiment where we melted and acid and then left it cool and we measured the temperature it dropped fast but then it stayed on 55 degrees for over five minutes and then it dropped again, I understand that they are the correct results - but why?
thanks for answering
xx

2007-12-11 06:56:57 · 2 answers · asked by poshpanda:-) 4 in Chemistry

How many moles of ions are in one mole of Ca(OH)2 ?

How many moles of electrons in one mole of OH- ions?

From OCR Foundation Chemistry, Jan 07

Couls someone please tell me the answer and how they worked it out ?

2007-12-11 06:54:50 · 4 answers · asked by Anonymous in Chemistry

Hypophosphorous acid, H3PO2, has the structure (HO)PH2O, in which two atoms are bonded to an O atom. For each bond to an H atom, decide whether it is polar or nonpolar. Assume that only polar-bonded H atoms are acidic. Write the balanced equation for the complete neutralization of hypophosphorous acid with sodium hydroxide. A 200.0-mL sample of H3PO2 requires 22.50 mL of 0.1250M NaOH for the complete neutralization. What is the molarity?

2007-12-11 06:54:47 · 3 answers · asked by Anonymous in Chemistry

How many moles of ions are in one mole of Ca(OH)2 ?

How many moles of electrons in one mole of OH- ions?

From OCR Foundation Chemistry, Jan 07

Couls someone please tell me the answer and how they worked it out ?

2007-12-11 06:50:40 · 1 answers · asked by Anonymous in Chemistry

2007-12-11 06:46:55 · 5 answers · asked by Jessica A 1 in Mathematics

2007-12-11 06:44:14 · 3 answers · asked by Caty - 1 in Other - Science

i forgot if it would be aluminium, copper,magnesium,or tin. i know it is one of them...

2007-12-11 06:42:43 · 1 answers · asked by pie 2 in Chemistry

How much of a 20% copper alloy should be mixed with 200 oz, 50% copper alloy in order to get an alloy of 30%?

2007-12-11 06:41:14 · 3 answers · asked by rspringstead2003 1 in Mathematics

1.convert 0.50 kilometers into meters
a. 0.0050 m
b. 50 m
c. 5.0 x 10² m
d. 5.0 x 10³ m

2. express this measurement in standard scientific notation: 501 000
a. 501 x 10 ³
b. 5.01000 x 10 ⁵
c. 5.01 x 10 ⁵
d. 0.501 x 10 ⁶

3. a student measures a length to be 3.4 cm, then 3.4 cm again. the ability of the student to reproduce the measurement exactly shows he has very good:
a. accuracy
b. extrapolation
c. precision
d. interpolation

4. the number of significant digits in the measurement 60.080 kg is:
a. 2
b. 3
c. 4
d. 5

5. which of the following measurements contains zeros that are not significant?
a. 3.050 x 10⁵ mm
b. 0.0053 m
c.45.020 cm
d. 101 g

2007-12-11 06:38:51 · 4 answers · asked by Anonymous in Physics

2007-12-11 06:33:53 · 7 answers · asked by Jonathan S 2 in Mathematics

I need to know why you can't re-freeze something u had already put in the freezer and defreezed. Why is it bad, what happens to the molecules and everything?

2007-12-11 06:30:37 · 2 answers · asked by Acting_addict 2 in Chemistry

2007-12-11 06:26:43 · 34 answers · asked by Jonathan S 2 in Mathematics

My wife and I are interested in doing some investigation, but we’ve never done it before. I’d like to try it has a hobby, just to see what it would be like. I’ve seen the trips, but haven’t gone on one because I was already at the Queen Mary (for a different reason) and although it did feel really creepy in some areas, nothing else really happened.

Has any of you gone on these group trips and seen anything or is it a waste of money?

And if you have any suggestions on a place I’d love to hear about some good spots and what you may have seen.

I just don’t want to waste money and I do understand that ghosts don’t perform on demand, but I’d like to get something out of the trip other than a good sandwich at the local deli.

2007-12-11 06:24:05 · 9 answers · asked by Anonymous in Paranormal Phenomena

2007-12-11 06:20:04 · 3 answers · asked by kat 1 in Chemistry

The most prominent line in the emission spectrum of chromium is found at 425.4nm. Other lines in the chromium spectrum are found at 357.9nm, 359.3nm, 360.5nm, 427.5nm, 429.0nm, and 520.8nm.
a) which of these lines represents the most energetic light?
b) what color is the wavelength at 425.4nm?

2007-12-11 06:18:18 · 1 answers · asked by bobbythompson 2 in Chemistry

(formulae for respiration)

2007-12-11 06:18:12 · 4 answers · asked by Anonymous in Other - Science

I heard that cows can't walk up stairs, fact or urban myth?

2007-12-11 06:17:50 · 14 answers · asked by Anonymous in Zoology

For a superior planet, which elongation, large or small, and configuration is least favorable for observation?

2007-12-11 06:12:25 · 2 answers · asked by Anonymous in Astronomy & Space

29/50 + 11/50
If there is any reducing involved you may do so, if not leave it as it is.

2007-12-11 06:12:04 · 4 answers · asked by - 1 in Mathematics

factor completely:

1. 9a^2 - 100

2. 2a^4 - 18a^2

3. t^2 -(t - 1)^2

2007-12-11 06:12:04 · 4 answers · asked by Anonymous in Mathematics

For example, in distillation they use the coiled pipes to condense a gas. I assume this would work for cooling liquids as well. Why is this happening? I figure the coiled structure is creating a means for more movement and resistance, which would create more heat.

2007-12-11 06:10:42 · 3 answers · asked by Anonymous in Chemistry

Whats the best direction in the nights sky for viewing the meteor showers N, S , E , W , best constellation, or will they cover entire sky?

2007-12-11 06:08:16 · 4 answers · asked by april_y75 1 in Astronomy & Space

Two bacteria colonies are cultivated in a laboratory. The first colony has a doubling time of 2 hours and the second a doubling time of 3 hours. initially, the first colony contains 1000 bacteria and the second colony 3,000 bacteria. At what time t will sizes of the colonies be equal??

I'd appreciate any help. Thanks.

2007-12-11 06:06:07 · 5 answers · asked by yefimthegreat 1 in Mathematics

My daughters teacher came up with the question for her maths. I haven't got a clue how to work it out , help please!!

2007-12-11 06:03:28 · 12 answers · asked by Anonymous in Mathematics

2007-12-11 06:03:17 · 2 answers · asked by kat 1 in Chemistry

2007-12-11 06:03:02 · 2 answers · asked by Ken B 1 in Mathematics

Any time you look at two numbers taken from the same thing, what are the two possible reasons the numbers are different?

2007-12-11 06:02:20 · 4 answers · asked by Booker T "Right There" 5 in Engineering

2007-12-11 06:01:59 · 39 answers · asked by keithlrichardson 2 in Mathematics

2007-12-11 06:01:07 · 2 answers · asked by Courtney L 1 in Earth Sciences & Geology