Chemistry - October 2006

2006-10-27 13:45:13 · 2 answers · asked by Anonymous

2006-10-27 13:30:17 · 7 answers · asked by noxturnxonxred 2

2006-10-27 13:16:27 · 6 answers · asked by j 1

type of agar and temperature needed to culture Nanochloropsis oculata??

2006-10-27 12:51:31 · 1 answers · asked by qiqi 1

2006-10-27 12:40:22 · 12 answers · asked by Anonymous

on the first day of school, a science teacher in my school took a mixture of chemicals or something and diped stuff into it (like a dollar bill n stuff) and she lit it on fire, but it didn't burn. anybody know the mixture?

2006-10-27 12:14:31 · 5 answers · asked by LITTLE GREEN GOD 3

2006-10-27 12:09:06 · 3 answers · asked by clevat 2

3.01 x 10^23 molecules of water.

2006-10-27 12:07:30 · 4 answers · asked by Sun 1

2006-10-27 11:59:10 · 6 answers · asked by yoyo 2

One of the experiments I have to do is 'The Beer Lambert law' - Spectroscopy'. Where I have to measure the absorbance of standard solutions of Ferroin complex.
I would also like to know:
1) how can I calculate the concentration of iron from the absorbance?
2) Ater plotting a graph of absorbance vs. concentration (for the samples of known concentration), how can I then calculate the molar absorptivity of ferroin at 470nm?
3)How can I then use the graph to establish the total mass of iron in the the tablet toether with estimated errors?
4)What colour of light does 470nm correspond to and why was this wavelength chosen for this experiment?

[p.s. Sorry for asking so much questions - It's just that I cannot find any suitable answers and my lecturers won't help me!] Thanks to anyone that can help me out.

2006-10-27 11:58:29 · 2 answers · asked by clevat 2

2006-10-27 11:48:08 · 10 answers · asked by LITTLE GREEN GOD 3

2006-10-27 11:41:01 · 2 answers · asked by Anonymous

1: In a neutral atom, the number of electrons equals ____________.
ions
protons
neutrons
none of the above


2: A neutral atom that contains 92 protons contains _______ electrons.
92
46
29
none of the above


3: Elements that have 8 electrons in their outer shell are most likely to be ___________.
stable
unstable
both 1 and 2
neither 1 nor 2


4: Isotopes have the same number of electrons but different ________.
protons
neutrons
sizes
none of the above


5: The atomic weight of an atom is equal to the number of protons plus the number of ________.
energies
isotopes
neutrons
none of the above


6: The unit of electricity in an atom is the electric ___________.
charge
magnetism
energies
none of the above


7: An electrically charged atom is called a(n) __________.
proton
neutron
ion
none of the above


8: Atoms that have the same number of protons but different numbers of neutrons are called ____________.
isotopes
similar
neutral
none of the above


9: Elements which have lost an electron are called
protons
ions
neutrons
none of the above


10: What is the charge of an electron?
positive
negative
neutral
none of the above


11: What is the charge of a proton?
positive
negative
neutral
none of the above


12: In an atom, the protons and neutrons are found ___________.
in the nucleus of the atom
in the atom's outer shell
both 1 and 2
none of the above


13: In an atom, the electrons are found in __________.
nucleus
the atom's electron shells
both of the above
none of the above


14: The Electron Theory was developed by ____________.
Albert Einstein
John Dalton
Aristotle
none of the above


15: What is the process of oxidation?
The electron jumps to another electron shell.
The atom gains an electron.
The atom loses or gives up an electron to another atom.
none of the above


16: In chemistry we often read the periodic table. What is a vertical column called?
a period
a group
both 1 and 2
none of the above


17: When reading the periodic table, a horizontal row of elements is called ____________.
a period
a group
both 1 and 2
none of the above


18: Generally speaking, how would you describe the chemical activity of a group of elements as you go down a column in the periodic table?
The chemical activity among the elements in the vertical row increases.
The chemical activity among the elements in the vertical row decreases.
remains about the same
none of the above


19: During chemical changes the number of neutrons in the nucleus of atoms______.
increases
decreases
remains the same
none of the above


20: What is a chemical reaction?
It depends on the number of neutrons.
It depends on the number of protons.
It's hard to tell.
Atoms of the same or different elements either share electrons, gain, or lose electrons.

2006-10-27 11:25:40 · 6 answers · asked by Anonymous

1: In 1803 a famous version of the atomic theory was announced by
Dalton
Moseley
Priestly
Rutherford


2: The molecular weight of Mg3(PO4)2 is
189
262
354
448


3: The number of atoms represented by the formula (NH4)2Cr2O7 is
11
18
19
23


4: The symbol for antimony is
A
Sb
Sc
Se


5: The formula Cl2 represents one
atom
ion
molecule
radical


6: A substance having a molecular (formula) weight of 58 is
CaSO4
HCl
KNO3
Mg(OH)2


7: The number of atoms in the ozone molecule is
one
two
three
four


8: The total number of atoms of carbon in the formula K3Fe(CN)6 is
one
six
three
twelve


9: The smallest part of an element taking part in a chemical change is a(n)
molecule
atom
compound
mixture


10: The weight of one atom of oxygen is known as the
atomic weight
valence
charge
combining power


11: The sum of the weights of the atoms of a compound is known as the compound's
valence
combining power
molecule
molecular weight


12: The one or two letters used to represent an atom of an element are called a(n)
atom
symbol
molecule
compound


13: A group of symbols representing one molecule of a substance is called a(n)
atom
formula
equation
subscript


14: Two atoms joined together as in H2 make up a(n)
monatomic molecule
diatomic molecule
equation
none of the above


15: Numbers placed before a formula to represent more than one molecule of a substance are called
subscripts
coefficients
constants
remainder

2006-10-27 11:15:26 · 3 answers · asked by Anonymous

I Solid
II Liquid
III Gas

A. I only
B. II only
C. III only
D. I and II only

2006-10-27 10:47:41 · 9 answers · asked by Ashley C 1

2006-10-27 10:41:49 · 5 answers · asked by Anonymous

carbon chloride, carbon (IV)chloride, chlorine carbonide, or carbon tetrachloride,

2006-10-27 10:35:59 · 4 answers · asked by Anonymous

Please Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

2006-10-27 10:15:01 · 3 answers · asked by I-Love-the-Skin-Im-In 2

When treated with sodium iodide in acetone, benzyl chloride reacts much faster than 1-chlorobutane, even though they are both primary alkyl halides. Why does this rate difference occur?? also, would an SN2 reaction occur when crotyl chloride is placed in sodium iodide in acetone. If so, would it occur at room temp. or only once heated. Would an SN2 reaction occur if it was in silver nitrate in ethanol???-and if so, at room temp. or when heated? Thanks for any help!

2006-10-27 10:02:35 · 1 answers · asked by Me 1

2006-10-27 08:53:35 · 10 answers · asked by andrewil07 1

What is efficiency measured in? Low resolution suggests the column is efficient - how low is low?

2006-10-27 08:34:24 · 2 answers · asked by the forensics kid 1

2006-10-27 08:30:14 · 7 answers · asked by tdavis570 1

2006-10-27 08:11:44 · 7 answers · asked by Anonymous

2006-10-27 07:56:30 · 8 answers · asked by Anonymous

2006-10-27 07:44:36 · 4 answers · asked by Anonymous

2006-10-27 07:43:04 · 5 answers · asked by Crystaly s 1

2006-10-27 07:38:42 · 5 answers · asked by Anonymous

2006-10-27 07:25:35 · 3 answers · asked by Laura H 1

i keep on thinking 3000, but considering this is a lab for school it seems reeeeeeeeeeeeeeeeeeeally unreasonable.

2006-10-27 07:07:18 · 4 answers · asked by Anonymous

2006-10-27 07:06:13 · 4 answers · asked by joseph j 1