Chemistry - February 2007

a) Infrared
b) Ultraviolet
c) Visible Light

2007-02-22 14:32:30 · 3 answers · asked by precious_angel321 3

a) Visible Light
b) X-rays
c) Radio

2007-02-22 14:30:58 · 11 answers · asked by precious_angel321 3

What percentage of the polonium-218 will remain after 9 minutes? (The answer has to be in significant figures)

Please help me with this......

2007-02-22 14:28:20 · 1 answers · asked by precious_angel321 3

I've always wondered what dissolves erasers,
Does anyone know?

2007-02-22 14:26:30 · 8 answers · asked by ayla_1o1 1

What mass of barium sulfate can be produced when 100.0 mL of a 0.100 M solution of barium chloride is mixed with 100.0 mL of a 0.100 M solution of iron(III) sulfate?

2007-02-22 14:21:26 · 2 answers · asked by ? 2

_ Chemical Kinetics
-Chemical equilibrium
-Acids and Bases
-Acid-base equilibra and solubility equilibria
-Entropy, free energy, equilibrium
- Electrochemistry

which topic here is the easiest and hardest to cover?

2007-02-22 14:13:17 · 2 answers · asked by avalentin911 2

I am trying to set up a water bath experiment with constant 5ppm free chlorine. I have the means of controlling the chlorine level but I need real time monitoring of the chlorine. The monitoring system needs to output the reading to a computer/data acquisition board. The simpler the better, and money is not an issue.
I've done some research and found some options, but any advice would be greatly appreciated.

2007-02-22 14:02:25 · 1 answers · asked by nbcTVshows 1

1. for a chemical reaction to occur,
a. chemical bonds must break
b. aoms must rearrange
c. new bonds must form
d. all of the above


2. A ______ indicates the chemical makeup of a substance by showing how many of each kind of atom is present in a molecule.
a. chemical symbol
b. chemical formula
c. chemical reaction
d. chemical change


3. Increasing the concentration ____ the number of reactant particles present and ____ the distance between them.
a. increase, increase
b. increase, decrease
c. decrease, increase
d. decrease, decrease

2007-02-22 14:01:44 · 4 answers · asked by jennifer 1

Need help with doing this project i need cheap objects made of Lutetium need at least 5. Lutetium is element 71. please need help

2007-02-22 13:57:59 · 2 answers · asked by slam_ups2004 1

Question 1
How would you separate:
1- a mixture of powdered copper sulfate and powdered copper metal?
2- a solid alloy (amalgam) of gold and mercury)
3- a mixture of sugar, iron filings and aluminium powder?

Question 2:
If a metal Y forms a phosphate compound with the formula YPO4, what would be the correct formual for the sulfide of Y?
a) YS
b) YSO4
c) Y2S
d) Y2(SO4)3
e) Y2S3

Question 3:
If you are given the atomic number of an element, which of the following would you already know?
a) mass number
b) number of possble isotopes
c) number of neutrons
d) number of electrons in the nucleus of the atom
e) number of electrons in a neutral atom of the element

2007-02-22 13:45:49 · 2 answers · asked by Anonymous

produced?

CaC2 (s) + 2H2O (l) ----> Ca(OH)2 (aq) + C2H2 (g)



How do i go about solving this?

2007-02-22 13:45:41 · 4 answers · asked by snowangels 2

Question 1:
A rock such as granite could be classified as a mixture because it:
a) consists of more than one type of atom
b) is a natural solid
c) may be broken down into separate compounds by physical processes
d) is homogeneous in composition
may be only separated into its constituent elements by chemical processes

Question 2:
Which of the following processes would be the most suitable for removing only undissolved solid impurities from a sample of sea water?
a) chromatography
b) distillation
c) evaporation
d) filtration
e) crystallisation

Question 3: Which of the following involve chemical changes and which involve only physical changes?
1-growth of a plant
2- kicking a football
3- magnetising a screwdriver
4- production of sound by the vocal cords
5- running a car engine
6-healing a wound

Thankyou! Please be certain about your answers and tell me why it is that. Thankyou.

2007-02-22 13:35:30 · 4 answers · asked by Anonymous

Question 1
I have a diagram which represents an insoluble salt being separated from a liquid by filtration. Once the liquid has passed throught the filter and the insoluble salt is left behind, what is the liquid which has gone into the beaker which is underneath the filter?
a) filtrate
b) distillate
c) solute
d) solution
e) residue

Question 2:
Which of the following processes could be used to obtain water from a solution of sodium chloride and water?
a) distillation
b) chromatography
c) filtration
d) evaporation
e) decantation

Question 3:
A pure substance which is composed of different types of atoms always present in the same proportions is:
a) a mixture
b) an element
c) a heterogeneous mixture
d) a compound
e) a solution

Question 4:
The process of decantation is normally used to separate
a) solid particles from a liquid
b) a liquid from another liquid
c) a dissolved substance from a liquid
d) a filtrate from a solvent
e) a filtrate from a distillate

2007-02-22 13:27:30 · 4 answers · asked by Anonymous

H2(g) + I2(g) ↔ 2HI Temperature = 731K




2.10 mol of H2 and 2.10 mol of I2 are placed in a 1.00 L vessel. What is the equilibrium concentration of I2 in the gaseous mixture?
The equilibrium constant is K = 49.0


***HINT Normally you would need to solve a quadratic equation here since K is large.
However, in this case the intial concentrations of the two reactants are the same.
You can set up the equilbirium ratio (products over reactants) in terms of x, set it equal to K in the usual way,
then take the square root of both sides.
Then solve for x in the resulting linear equation.
OR you can solve the quadratic equation, if you prefer.

2007-02-22 13:18:38 · 2 answers · asked by Jessica R 1

For the ff. reactions, find the ff.
a. which of the reagents is the limiting reagent
b. what is the maximum amt. of each product that can be formed
c. how much of the other reagent is left over after the reaction is complete

1. consider the ff. reaction
3 NH4NO3 + Na3PO4 -> (NH4)PO4 + 3 NaNO3

Assuming that we started with 30 grams of ammonium nitrate and 50 grams of sodium phosphate.


and the other problem is 3 CaCO3 + 2 FePO4 -> Ca3(PO4)2 + Fe2(CO3)3

can anyone please help me! i so need help! i dont want to fail chemistry class =(

2007-02-22 13:18:19 · 2 answers · asked by Anonymous

2007-02-22 13:18:10 · 2 answers · asked by Anonymous

2007-02-22 13:14:03 · 6 answers · asked by Sandra 2

2007-02-22 13:10:11 · 2 answers · asked by Sandra 2

I know that the molar mass of AlCl3 is 133.341g but I forget where to go from there.

2007-02-22 13:10:02 · 2 answers · asked by nedoglover 4

And if anyone knows, why is ethanol completely miscible with gasoline while methanole is not (it separates into two layers)?

2007-02-22 13:07:22 · 2 answers · asked by loislanepoet 2

2007-02-22 13:02:33 · 2 answers · asked by Sandra 2

1. Name 4 thing that can spped up a chemical reaction? And please explain why they increase the rate of reaction ?

2.What is a chemical reaction(what takes place in a chemical reaction?)

3. The substances formed a chemical reaction are____
a. Symbols
b. products
c. yield

2007-02-22 12:57:51 · 6 answers · asked by jennifer 1

balanced equation for each combined substances or elements w/e they r:
1.cobalt nitrate and sodium hydroxide
2.copper sulfate and sodium hydroxide
3.silver nitrate and sodium chloride
4.nickel nitrate and sodium hydroxide
5.lead nitrate and potassium iodine

2007-02-22 12:48:57 · 3 answers · asked by Anonymous

what is the chemical equation for:(when they combine)
1.cobalt nitrate and sodium hydroxide
2.copper sulfate and sodium hydroxide
3.silver nitrate and sodium chloride
4.nickel nitrate and sodium hydroxide
5.lead nitrate and potassium iodine

2007-02-22 12:46:54 · 3 answers · asked by Anonymous

HF+KOH
HNO2+NaOH
Ca(OH)2+H2CO3

2007-02-22 12:22:59 · 4 answers · asked by Bella 2

Include straight and branched chain compounds. PLZ help me ASAP.

2007-02-22 12:21:06 · 2 answers · asked by kcc 1

2007-02-22 12:18:38 · 5 answers · asked by Anonymous

2007-02-22 12:06:24 · 5 answers · asked by redalert 2

I have the mass of a condensed vapor, pressure, temperature while in boiling water, and the volume of the test tube it was in. I now need to calculate the molecular mass. Help?

Thanks!

2007-02-22 12:05:47 · 1 answers · asked by writergirl 3

Are there equations to prodict it? If so can you direct me to a website to learn them?

2007-02-22 11:51:41 · 4 answers · asked by Anonymous