Chemistry - September 2007

M NaOH? Show your work and mind significant figures?

2007-09-26 04:49:04 · 2 answers · asked by forlaniz3 2

2007-09-26 04:44:38 · 2 answers · asked by lana l 1

21) iodine-131 and iodine-127 are examples of __?
A nuclei
B isomers
C isotopes
D neutrons

22) the __ is where the electron is most likely to be found.
A energy level
B electron orbit
C electron coud
D orbit

23) in a lewis dot diagram, the dots represent __ in the atom.
A all the electrons
B the valence electrons
C the protons
D the neutrons

24) which groups are considered to be transition elements?
A 1 and 2
B 3 through 12
C 1,2 and 18
D 13 through 18

25) an example of a chemical formula is __.
A. Na
B. 4.5 g/mL
C. H2SO4
D. d= 13.6 g/l

2007-09-26 04:42:37 · 3 answers · asked by Anonymous

2007-09-26 04:41:09 · 3 answers · asked by forlaniz3 2

2007-09-26 04:39:33 · 9 answers · asked by forlaniz3 2

In LongDrug, there are 2 rubbing alcohol, ethyl alcohol and isopropyl alcohol. What is the difference between them? Thank you!

2007-09-26 04:39:27 · 3 answers · asked by JenJen 2

2007-09-26 04:35:14 · 1 answers · asked by lana l 1

Soon choosing my A-level subjects!

Really stuck I really want to do something in forensics!

Arrrr


HELP!

(In UK)

2007-09-26 04:34:43 · 2 answers · asked by Lynzy 5

2007-09-26 04:34:40 · 2 answers · asked by forlaniz3 2

6. the best way to understand the submicroscopic world is with ___
A. powerful microscopes
B. very accurate measuring devices
C. physical properties
D. models

7 an example of a chemical change is __
A. melting
b. electrical conductivity
c. burning
d. density

8 the structure of matter refers to its __
a. behavior
b. composition
c. measurements
d. reactions

9 water and hydrogen peroxide are both composed of atoms of hydrogen and oxygen, the differences lie in the __ arrangement of the atoms.
A. behavioral
B. composed
C. macroscopic
D. submicroscopic

10 when ice melts and becomes liquid water, it has undergone a __
A. chemical change
B. chemical propert
c. physical change
d. physical property

11 in ocean water, salt is a(n) __
a. alloy
b. solute
c. solution
d. solvent

12 how many atoms are present in one unit of sodium sulfate, Na2SO4?
A. 1
B. 2
C. 4
D. 7

15 the second row of the periodic table includes__ elements
a. 2
b. 8
c. 18
d. 32

2007-09-26 04:30:40 · 2 answers · asked by Anonymous

in a container. What is the amount and concentration of sodium hydroxide solution she must add to this in order to end up with 8 liters of 27% solution? your help is greatly appreciated!!!

2007-09-26 04:26:47 · 2 answers · asked by sugar lady 1

H2SO4+KOH= g + f

Now what i need here is the atomweight .. or something like that (sry ime from europe) if i know that the weight of the H2SO4 is 0.5 mol.

So basicly i need the atomweight of each and every element

2007-09-26 04:13:22 · 4 answers · asked by Simon T 2

Any kind of food additive will work,

2007-09-26 04:10:02 · 5 answers · asked by mark s 1

the problem is: Calculate the density if the mass of a solid material is measured as 15.00 grams and its volume is measured as 5.0 cm^3? Round off your answer to the proper number of significant figures.

2007-09-26 04:02:33 · 3 answers · asked by IDchecker27 2

a) which is the limiting reactant?
b) how many grams of NO and H2O form?
c) how many grams of the excess reactant remain after the limiting reactant is consumed?

2007-09-26 04:01:51 · 2 answers · asked by cherubimangel85 1

2007-09-26 03:56:53 · 2 answers · asked by tangelo316 1

I'm lokking for this manual in Amazon but i dont fined it im looking for this or the web site that may be i can fined the answer of the question of the first 7 chapter from the Quantum Chemistry IRA N.LEVINE book(please this is something vrey vrey important for me im rely rely need it.

2007-09-26 03:47:57 · 2 answers · asked by rakan e 1

2007-09-26 03:43:37 · 7 answers · asked by Jordan D 1

2007-09-26 03:43:15 · 3 answers · asked by Jordan D 1

based on aromatic reaction..please explain how does the presence of nitro group in benzene effect the substitution of the next electrophile

2007-09-26 03:32:01 · 4 answers · asked by suser 1

Lithium reacts with oxygen to make lithium oxide oxide. What is the maximum mass of lithium oxide (g) that could be prepared from 5.74 g of Li(s) and 13.73 g of O2(g)?

2007-09-26 03:20:31 · 1 answers · asked by Anonymous

Write the ionic equation for the reaction, if any, between:

a)HNO3 and Na2CO3
b) NH3 and KCl

(please help me.. thank you!)

10 pts for the best answer(as always)

2007-09-26 03:03:16 · 2 answers · asked by carbonara 2

2007-09-26 02:38:07 · 2 answers · asked by Anonymous

2007-09-26 01:44:09 · 9 answers · asked by Carmel 1

Just to make sure I have the right answer. When doing a simple distillation, the reason why the liquid in the distillation flask doesn't evaporate all at once once the boiling point is reached is: the liquid distillated is separated from the volatile liquid still in the conical vile. You are purifying the liquid so not all the substance can be vaporized all at once.

2007-09-25 18:34:29 · 3 answers · asked by iheartdr.sambeckett 4

A typical formulation for window glass is 75% SiO2, 15% Na2O, and 10% CaO by mass.

What masses of sand (SiO2), sodium carbonate, and calcium carbonate must be combined to produce 1.00 kg glass after CO2 is driven off by thermal decomposition of the carbonates?
(Express your answers to 1 decimal place.)

Mass of sand (in grams) 1.-----
Mass of sodium carbonate (in grams) 2.-----
Mass of calcium carbonate (in grams) 3.-----

2007-09-25 17:59:55 · 1 answers · asked by Ahmed A 1

He
N2
HCl
H2

2007-09-25 17:33:15 · 1 answers · asked by Anonymous

5. A gas sample collected at 35.0?C and a pressure of 710 torr has a volume of 200 mL. The temperature and pressure are changed, and the gas is compressed to 150 mL. The new temperature is 40.0?C, what is the new pressure?
1.27 atm
1.08 x 103 torr
541 torr
0.712 atm

2007-09-25 17:27:39 · 2 answers · asked by Anonymous

well i remembered a jesus saying (if salt looses its saltyness how can it get its saltyness back)?.so it made me think if it loose its saltyness its just a grain of sand.

2007-09-25 17:24:35 · 6 answers · asked by mark w 1

The base dissociation constant of pyridine (C5H5N) is Kb = 1.7 x 10-9.

At 25 °C, Keq = 0.0146 for the following reaction:
PCl5 PCl3 + Cl2

2007-09-25 17:05:43 · 2 answers · asked by virgo 1