Chemistry - January 2007

I have to do a presentation in chemistry on extracting iron from it's ore [Haematite] and I'm really fed up of just finding the boring old facts about how it's done [reacting with carbon and carbon monoxide] etc.
Has anyone out there got ANY interesting facts about this process that will make my presentation just a bit more appealing, or will everyone just have to fall asleep?!
Thanks!
Lorna

2007-01-29 06:43:10 · 1 answers · asked by Anonymous

give an example of an exothermic reaction that produces
- heat & light
- electricity
- several forms of energy at once.



1.a) write a word equation to represent the breakdown of water into its two elements.

b) what form of energy can cause this reaction to take place?

c) compare this reaction to the burning of hydrogen. how are the two reactions similar? how are the different?

2007-01-29 06:33:43 · 1 answers · asked by Guitr Playrrr 2

2007-01-29 06:15:46 · 9 answers · asked by Anonymous

Question: state whether each of the following substances is likely to be very soluble in water. Explain!

(a) lithium nitrate
(b) glycine, H2NCH2COOH
(c) Pentane
(d) Ethylene glycol, HOCH2CH2OH

My approach:
this is a very tough question for me b/c i didnt cover it that much. please give me an explanation of why or why not any of these chemicals are soluble. THANKS! (i award best answers)

2007-01-29 05:50:46 · 3 answers · asked by Jimmy 3

Calculate the standard enthalpy change in kJ for the production of 14.4 g of SO3 (g) from a reaction where the reactants and products are:

reactants: SO2 (g) O2 (g)

products: SO3 (g)

2007-01-29 05:47:52 · 1 answers · asked by sunyrob 1

1. CHEMISTRY-
cud anyone plz give me d balanced chemical equations involving the reactions of magnesium and aluminium with zinc sulphate?


2.PHYSICS-
when a ray of light undergoes refraction at the surface of separation of 2 different media,what happens to its wavelength?

THANKS IN ADVANCE TO ALL OF U WHO ANSWER......I'LL B VERY OBLIGED !!

2007-01-29 05:47:36 · 6 answers · asked by Anonymous

4.20 g of a hydrocarbon, C20H16, were burned in excess oxygen in a constant-volume calorimeter surrounded by 1250. g of water. As a result the temperature of the water and the calorimeter rose from 21.3 oC to 26.1 oC. The heat capacity of the calorimeter was 251.040 J/oC.





Calculate DE (kJ/mol) for the combustion of the hydrocarbon based on these readings.





Enter a numeric answer only, do not include units in your answer.

2007-01-29 05:46:52 · 1 answers · asked by sunyrob 1

A piece of lead having a mass of 107.5 g is placed in an empty graduated cylinder.
27.0 mL of water is then poured slowly and carefully into the same cylinder.
The final water level would then indicate the total volume of the materials in the graduated cylinder.
What is this total volume in millileters?

2007-01-29 05:38:19 · 1 answers · asked by dannyg11us 1

Question: (a) volume in liters of 2.26 M potassium hydroxide that contains 8.42 g of solute. (b) number of Cu2+ ions in 52L of 2.3 M copper(II) chloride. (c) molarity of 275 mL of solution containing 135 mmol of glucose.

My Work:
(a) 8.42g KOH x (1mol/56g) = .150 mol KOH

2.26mol/L / .150 mol = 15.1 L --- answer

(b) 2.3 mol/1 L x 52L = 119.6 mol CuCl2
119.6 mol CuCl2 x (1mol Cu2+ ions/ 1 mol CuCl2) x (6.022e23 ions/ 1 mol Cu2+) = 7.20e25 ions -- answer

(c) 275 mL x (1L/1000 mL) = .275 L
135mmol x (10^-3mol/ 1mmol) = .135 mol

.135 mol/.275 L = .491 M glucose -- answer

if you see anything wrong PLEASE correct it! thanks

2007-01-29 05:35:50 · 4 answers · asked by Jimmy 3

2007-01-29 05:30:36 · 17 answers · asked by Anonymous

2007-01-29 05:29:20 · 4 answers · asked by Anonymous

science experiments

2007-01-29 05:28:53 · 12 answers · asked by lovelyshay 1

water

2007-01-29 05:27:19 · 5 answers · asked by lovelyshay 1

lipid bilayer of all biological membranes is acting as a capacitor. i want to know the charge density of muscle,epithelial,neuron,endo peri &myocardium cells

2007-01-29 05:20:10 · 1 answers · asked by sreehari.g g 1

A certain liquid has a density of 2.67 g/cm^3. 30.5mL of this liquid would have a mass of _____ Kg. Can anyone show me how to work this problem? Thanks

2007-01-29 05:15:45 · 4 answers · asked by James F 3

Question: the mineral galena is composed of lead(II) sulfide and has an average density of 7.46 g/cm^3. (a) how many moles of lead(II) sulfide are in 1.00 ft^3 of galena? (b) how many lead atoms are in 1.00 dm^3 of galena?

My approach:

(a) 7.46g FeS x (10^6 cm^3/ 35.51 ft^3) x (1 mol/ 88 g FeS) = 2400.8 mol/1 ft^3 = 2400.8 mol FeS ---My Answer!

(b) 7.46 g/ 1cm^3 x (1000 cm^3/1 dm^3) = 7460 g/ 1 dm^3 x (1mol/88 g FeS) x (1 mol Fe atom/1mol) x (6.022e23 atoms/1mol) = 5.11e25 Fe Atoms/dm^3 --- my answer!

If you see anything wrong PLEASE tell me what's wrong by correcting it. appreciate it!

2007-01-29 05:13:21 · 2 answers · asked by Jimmy 3

I have HBr - hydrobromous acid. i know it's wrong, but what is the answer? i will award a best answer for this.

2007-01-29 04:49:28 · 2 answers · asked by Anonymous

Question: an ionic compound forms when calcium (Z= 20) reacts with iodine (Z = 53). if a sample of the compound contains 7.4 x 10^21 calcium ions, how many iodide ions does it contain?

My approach:
7.4 x 10^21 Ca2+ x (2 I ions/ 1 Ca2+ ion) = 1.48 x 10^22 I ions

(i will award best answer)

2007-01-29 04:45:08 · 3 answers · asked by Anonymous

a) dew condensing on leaf
b) an egg turning hard when it is boiled
c) ice cream melting
d) a spoonful of batter cooking on a hot griddle

my approach:
a) physical change
b) no physical change
c) no
d) no

(i will award best answer)

2007-01-29 04:36:46 · 4 answers · asked by Anonymous

a) passing an electric current through molten magnesium chloride yields molten magnesium and gaseous chlorine.
b) the iron in discarded automobiles slowly forms reddish brown, crumbly rust.

my approach:
a) chemical property = magnesium chloride yields molten and cholrine cgas
physical property = electric current, molten, gas chlorine
b) chemical property = none
physical property = iron forms reddish and crumbly rust

2007-01-29 04:34:41 · 2 answers · asked by Anonymous

Do you know how to conjecture radiocarbon dating ln(N/No)=t1/2

2007-01-29 04:30:16 · 1 answers · asked by adv. 4

First prepare a stock solution that is 1.00 x 10-2 M in phosphate ion. How many g of Na3PO4 would you add to a 50 mL volumetric flask to to prepare this solution?

What is this concentration in ppm of phosphate?

2007-01-29 04:15:15 · 2 answers · asked by Anonymous

2H2(g) + O2(g) --> 2H2O(g) ΔH = −486.6kJ



Which of the following are true statements for the above chemical reaction ?



a) A phase change is involved


b) Two moles of hydrogen gas react with two moles of oxygen gas to
produce two moles of water vapor


c) Energy is absorbed by the system, the reaction species


d) If the reaction takes place at constant pressure, q = −483.6 kJ


e) ΔH for reacting four moles of hydrogen gas with two moles of
of oxygen gas is −977.2 kJ

2007-01-29 04:09:14 · 3 answers · asked by Anonymous

MgSO4 → Mg2+(aq) + SO42−(aq)

the change in enthalpy must be −91.3 kJ/mol



How much heat (kJ) is lost or gained by 309.0 ml of water when 5.40 g of MgSO4 is dissolved in the water ?

2007-01-29 04:06:49 · 1 answers · asked by Anonymous

This question goes to an analytical chemsit or biochemist or to an enzymologist. As it is mentioned above, what is the use of measuring enzymatic reaction by two analytical methods, like measuring by polarograph and spectrophotometer ?

2007-01-29 03:59:13 · 2 answers · asked by behailubgu 1

I need this by the friday after Monday January 29, 2007.

2007-01-29 03:56:14 · 4 answers · asked by gatorboi19884870 3

T is in degrees . what is the rate constant at t=80 degrees celsius

2007-01-29 03:51:00 · 1 answers · asked by shernitalbanks 2

What would be true of the densities of most solids and liquids at a temperature higher that the quoted one?

2007-01-29 03:23:24 · 7 answers · asked by Tami B 1

2007-01-29 03:22:38 · 6 answers · asked by Tami B 1

It is either aluminium or silver and I am not sure about it.

2007-01-29 03:21:55 · 4 answers · asked by Anonymous