Chemistry - February 2007

the chemical and physical properties of cornstarch?

2007-02-26 08:56:35 · 5 answers · asked by gm 2

2007-02-26 08:55:00 · 2 answers · asked by erjerome 2

Please give an example and tell why it is immiscible.

2007-02-26 08:52:47 · 2 answers · asked by SomeRandomKid 1

Can anyone help me solve these riddles?

1. For the pairs of atoms listed below, state whether they will tend to form ionic bonds, covalent bonds or polar covalent bonds. Explain the reason for your choice.

(a) Potassium and chlorine
(b) Iodine and iodine
(c) Oxygen and hydrogen

3. Using the ‘electron pair repulsion theory’, state and explain the shape of the following compounds and in each case sketcha diagram to show the arrangemant of the atoms in space, labelling the bond angles.
(a) AlCl3
(b) SiH4
(c) PCl5

4. Enthalpy changes for the reactions of carbon and aluminium with oxygen are given in the following equations, where all substances are in their standard states.

C(s) + O2(g) → CO2(g) delta H = -394 kJ mol -1

4Al(s) + 3O2(g) → 2Al2O3(g) delta H = -3352 kJ mol -1

(a) What is the value for the standard enthalpy of combustion of carbon?

(b) What is the value for the standard enthalpy of combustion of aluminium?

Thanks for any advice!

2007-02-26 08:51:21 · 2 answers · asked by DC 1

WHY THE LIGHT BULB LITS IN SALT WATER AND NOT IN SUGAR WATER?

2007-02-26 08:31:58 · 4 answers · asked by seherhashmi 3

I know that it starts with the letter a.

2007-02-26 08:02:01 · 10 answers · asked by Anonymous

what science experement could u do to detect the strength of a magnet?

2007-02-26 07:59:08 · 8 answers · asked by tammie x 1

My plant has an 800 gallon tank (of 120 degree water) that they need to empty, clean, and refill every 3 weeks. In order to dispose of the water properly, it needs to be ph neutral. I'm trying to come up with the most cost effective way to do this.

The current alkalinity level of the tank is 9, and I need to know exactly how much of what I would need to add to that to bring it down to 7.

I'm currently looking at pool chemicals, but I'm sure there has to be a better way. Thanks in advance for any help!

2007-02-26 07:58:59 · 2 answers · asked by FieryOutlaw 3

I totally forget how to solve titraton problems!!! help please?

2007-02-26 07:40:08 · 3 answers · asked by Anonymous

2007-02-26 07:34:12 · 1 answers · asked by Richard A 2

2007-02-26 07:33:24 · 3 answers · asked by Richard A 2

Predict the sign of delta H for each of the following reactions and explain your prediction

a) Li (g) + Na- (g) -> Li- (g) + Na (g)
b) Na+ (g) + K (g) -> Na (g) + K+ (g)

2007-02-26 07:31:19 · 1 answers · asked by Anonymous

1) do ionic substances dissolve in polar liquids?

2) do covalent substances dissolve in nonpolar liquids?

3) do ionic substances dissolve in nonpolar liquids?

please help!!! answer any that you can! thanks!

2007-02-26 07:27:04 · 1 answers · asked by mbroderickluver 2

It is listed in a chem book as a special class of binary compound with an H ion serving in place of a metal ion. I am confused as generally ionic bonding is between metals and non metals.

2007-02-26 07:24:31 · 2 answers · asked by Gideon 1

can we find any relations between "Standard electrode potential" of an element and the electorons of the last layer of it?

2007-02-26 07:13:54 · 1 answers · asked by sanaz 1

with the info on Boron, determine the average atomic mass:

Isotope: B-10 Percentage 18.88 and weight (u) 10.00
and
Isotope: B-11 Percentage 81.12 and weight (u) 11.00

how do i figure this out??

2007-02-26 07:09:03 · 3 answers · asked by laural8477 3

2007-02-26 07:08:27 · 2 answers · asked by Richard A 2

2007-02-26 07:07:13 · 4 answers · asked by krusty_blue_spaz 5

formula for this substance

potassium permanganate

2007-02-26 07:01:32 · 1 answers · asked by hunterz 2

Does anyone know of a safe, inhalable gas, to which colour and scent could be added, simulating cigarette smoke. The gas should not give off toxic substances when released, so can't be burnt. I was thinking, if the top end of substitute cigarette was lit, burning the end, this would cause the area behind it to heat up. This heating up could then release a gas which when combined with colouring chemicals and scent could simulate cigarette smoke.

2007-02-26 06:48:41 · 6 answers · asked by Anonymous

A. The elements carbon and hydrogen combining to form the compound methane.
B. Two compounds reacting chemically to form two different compounds.
C. Two samples of the element gold being melted together.
D. Water is heated and a vapor is formed.

2007-02-26 06:41:05 · 2 answers · asked by ladona c 1

I know the gas constant (R) units are L*atm / °K*mol. But I don't know if the mol unit is in grame-mol or kilograme-mol.
I want to calculate "n" in PV =nRT, so what unit do I get? Because after that I have to calculate Molarity.

2007-02-26 06:19:27 · 7 answers · asked by Quake 2

So I am having trouble with my basic math and have completely forgotten how to solve equations with scientific notation...

3.00x10^(17) x 6.63x10^(-34)

if you could explain how to get the correct exponent when solving these kinds of equations I would be appreciative...I get the right answer but never the right exponential value...

2007-02-26 06:14:48 · 4 answers · asked by guitar_dah_311 1

I need to know 2 questions...

1). The Stable ion that atoms of Chlorine commonly form.

2). Name some real - world applications that your element is involved with.

I think for 2 there is pool chemicals, salt, bleaching products...but I'm not sure about #1 I searched the net and it said NACI which I know is salt but is salt the right answer? Could some one please explain...please

Thanks

2007-02-26 05:59:01 · 1 answers · asked by Anonymous

Tarnish on silverware may be silver sulfide. How many moles of sulfer react with 7 moles of silver

2007-02-26 05:46:52 · 2 answers · asked by Nik-Nak 3

100 cubic feet (100cf) of carbon monoxide (CO) to carbon dioxide (CO2)?


thanks.

2007-02-26 05:32:01 · 2 answers · asked by frickenawesomekoreanandyouknowit 2

I have searched all over the internet for the Bohr - RUTHERFORD - Diagram of an atom of the element (chlorine). Does anyone know where to find it? I need this for school, please and thank you

2007-02-26 05:21:22 · 2 answers · asked by Anonymous

How many milliliters of 0.450 M Na2S2O3 solution are needed to titrate 2.405 g of I2 to the equivalence point?
I2(aq) + 2 S2O32-(aq) S4O62-(aq) + 2 I -(aq)

_______ mL

2007-02-26 05:16:03 · 3 answers · asked by lola_boo 1

Ex pH<7 due to the absorption of CO2 from the air.

H2O+CO2-->H2CO3

So what would happen to the pH in the water if it was boiled. Thanks

2007-02-26 05:09:42 · 9 answers · asked by Angel Eve 6

2007-02-26 05:01:12 · 7 answers · asked by Anonymous