Chemistry - December 2007

How many moles of ions are in one mole of Ca(OH)2 ?

How many moles of electrons in one mole of OH- ions?

From OCR Foundation Chemistry, Jan 07

Couls someone please tell me the answer and how they worked it out ?

2007-12-11 06:54:50 · 4 answers · asked by Anonymous

Hypophosphorous acid, H3PO2, has the structure (HO)PH2O, in which two atoms are bonded to an O atom. For each bond to an H atom, decide whether it is polar or nonpolar. Assume that only polar-bonded H atoms are acidic. Write the balanced equation for the complete neutralization of hypophosphorous acid with sodium hydroxide. A 200.0-mL sample of H3PO2 requires 22.50 mL of 0.1250M NaOH for the complete neutralization. What is the molarity?

2007-12-11 06:54:47 · 3 answers · asked by Anonymous

How many moles of ions are in one mole of Ca(OH)2 ?

How many moles of electrons in one mole of OH- ions?

From OCR Foundation Chemistry, Jan 07

Couls someone please tell me the answer and how they worked it out ?

2007-12-11 06:50:40 · 1 answers · asked by Anonymous

i forgot if it would be aluminium, copper,magnesium,or tin. i know it is one of them...

2007-12-11 06:42:43 · 1 answers · asked by pie 2

I need to know why you can't re-freeze something u had already put in the freezer and defreezed. Why is it bad, what happens to the molecules and everything?

2007-12-11 06:30:37 · 2 answers · asked by Acting_addict 2

2007-12-11 06:20:04 · 3 answers · asked by kat 1

The most prominent line in the emission spectrum of chromium is found at 425.4nm. Other lines in the chromium spectrum are found at 357.9nm, 359.3nm, 360.5nm, 427.5nm, 429.0nm, and 520.8nm.
a) which of these lines represents the most energetic light?
b) what color is the wavelength at 425.4nm?

2007-12-11 06:18:18 · 1 answers · asked by bobbythompson 2

For example, in distillation they use the coiled pipes to condense a gas. I assume this would work for cooling liquids as well. Why is this happening? I figure the coiled structure is creating a means for more movement and resistance, which would create more heat.

2007-12-11 06:10:42 · 3 answers · asked by Anonymous

2007-12-11 06:03:17 · 2 answers · asked by kat 1

100.0 liters of water steam collected at 127.0 degrees celsius ( under 1 atm) to ice at -20.0 degrees celsius. (Molar mass: O = 16.00 g, H = 1.008 g. The specific heat of ice is 2.03 J/g-degrees celsius, the specific heat of water is 4.184 J/ g- degrees celsius, the specific heat of steam is 1.99 J/g-degrees celisius. the heat of fusion is 6.01 kilojoules for water, and he heat of vaporization is 40.79 kilojoules for water)

2007-12-11 06:01:06 · 1 answers · asked by peluc 1

2007-12-11 05:58:50 · 1 answers · asked by Daniel P 2

are the following acidic, basic, or neutral.
a-purified tap water(pH=7)
b-Lemon Juice(pH=2.7)
Draino(pH=10)

2007-12-11 05:51:46 · 7 answers · asked by kat 1

Calculate the energy needed to change 10 grams of water from 70 degrees C to 110 degrees C.

I need the energy in Kcal.

2007-12-11 05:49:34 · 1 answers · asked by raullozoya@sbcglobal.net 1

What is the base-10 logarithm of the molar concentration of a salt, AX, with pKsp = 50.729?

2007-12-11 05:47:53 · 1 answers · asked by Kurls 1

Consider a salt of composition, A2B3. For this salt, pKsp = 86.909. What is the logarithm of the molar concentration of this salt?

2007-12-11 05:45:15 · 1 answers · asked by Kurls 1

Calculate the standard entropy change for the following reaction,

2 HgO(s) → 2 Hg(λ) + O2(g)

given S°[HgO] = 70.3 J/K·mol, S°[ Hg(λ)] =76.0 J/K·mol, and S°[O2(g)] = 205.1 J/K·mol.

a.+210.8 J/K
b.-216.5 J/K
c.+351.4 J/K
d.+497.7 J/K
e.+216.5 J/K

2007-12-11 04:37:15 · 3 answers · asked by Anonymous

Estimate the boiling point of carbon tetrachloride given the following thermodynamic parameters

CCl 4 (λ) CCl 4 (g)

ΔH°f(kJ/mol) -128.4 -96.0
ΔS°f( J/K·mol) 214.4 309.7
ΔG°f(kJ/mol) -57.6 -53.6

a.69 °C
b.109 °C
c.-272 °C
d.67 °C
e.25 °C

2007-12-11 04:34:35 · 0 answers · asked by Anonymous

I understand the initial process being thermal decomposition changing the compound into copper oxide. I would relish in the knowledge of how to then change this into copper. Please help. Thank you.

2007-12-11 03:47:44 · 3 answers · asked by Anonymous

2007-12-11 02:20:29 · 3 answers · asked by Anonymous

2007-12-11 02:18:53 · 1 answers · asked by s.perrone17 1

2007-12-11 01:43:51 · 4 answers · asked by Yoyo Y 1

The hydrogen sulphate (H2S) content of a water sample was assayed with electrolytically generated iodine. After 3.00 g of potassium iodide had been introduced to a 50.0 mL portion of the water, titration required a constant current of 0.0731A for a total of 9.20 min. The reaction was as followed:

H2S (aq) + I2 (aq) <=> S (s) + 2H+ (aq) + 2I-(aq)


Calculate the concentration of hydrogen sulphide (in mg/L) of the sample.

(given: relative atomic mass: S=32.1, H=1.0)

2007-12-11 01:36:47 · 2 answers · asked by Anonymous

0.1875 g/cm3

5.3 g/cm3

192 g/cm3

2007-12-11 00:52:36 · 3 answers · asked by Anonymous

2007-12-11 00:35:20 · 5 answers · asked by Anonymous

2007-12-11 00:10:29 · 1 answers · asked by jamie 1

2007-12-10 18:01:22 · 1 answers · asked by chewbacca87 1

2007-12-10 17:48:10 · 3 answers · asked by SICK MY DUCK! 1

2007-12-10 17:43:47 · 1 answers · asked by Anonymous

Is Pbcl2 or FeCl3 soluble?

2007-12-10 14:20:52 · 5 answers · asked by bbritney11 1

2007-12-10 14:19:45 · 3 answers · asked by girlygirl92194 1