Chemistry - May 2007

2007-05-06 19:06:46 · 1 answers · asked by Anonymous

2007-05-06 19:01:47 · 1 answers · asked by mona s 1

2007-05-06 18:41:13 · 1 answers · asked by shraddha d 1

2007-05-06 18:40:04 · 1 answers · asked by shraddha d 1

2007-05-06 18:23:50 · 1 answers · asked by RR_MXLI 2

A) What is the percent mass of chlorine in carbon tetrachloride?

1) percent?

B) partscoretotalsubmissions1----0/42----0/4----2--A 300 Watt electric heater puts out 300 Joules of energy per second. If an ice cube weighing 50.2 grams at -9.5 ºC is placed on the heater, how long will it take for the ice to completely vaporize (turn to steam)?
The specific heat of ice is 2.03 J/gºC, the specific heat of water is 4.184 J/gºC.

1)Minutes?
2) What percent of the total energy is used to vaporize the water (to change it to steam)?

2007-05-06 17:38:31 · 1 answers · asked by ♥ReKa♥ 2

A) Rank the following compounds in order of strongest to weakest intermolecular forces (note that ionic bonds can be classified as either an inter or intra molecular force).

NH3, He, N2, SrF2, CO2, Ne, HBr, H2O, KCl

B) Which of the following has individual molecules held together by intermolecular forces in a rigid crystal structure:
1)metallic solid
2)network solid
3)atomic solid
4)ionic solid
5)molecular solid

C) Which of the following has delocalized electrons throughout the solid:
1)metallic solid
2)network solid
3)molecular solid
4)ionic solid
5)atomic solid

D) Diamond and graphite can best be described as:
1)ionic solids
2)network solids
3)molecular solids
4)atomic solids
5)metallic solids

2007-05-06 17:36:01 · 1 answers · asked by ♥ReKa♥ 2

A: low temperature and low pressure.
B: high temperature and high pressure.
C: low temperature and high pressure.
D: high temperature and low pressure.
E: standard temperature and pressure.

2007-05-06 17:28:33 · 1 answers · asked by ♥ReKa♥ 2

You have a 25.0 L cylinder of helium at a pressure of 135 atm and a temperature of 23 °C. The He is used to fill balloons to a volume of 1.00 L at 0.982 atm and 27 °C. How many balloons can be filled with He? Assume that the cylinder can provide He until its internal pressure reaches 1.00 atm (i.e., there are 134 atmospheres of usable He in the cylinder).

2007-05-06 17:24:39 · 1 answers · asked by ♥ReKa♥ 2

The equation for the decomposition of mercury (II) oxide is as follows: 2HgO(s) + 182 kJ---> 2Hg (l) + O2 (g)

2007-05-06 17:15:06 · 1 answers · asked by Anonymous

My pool does not read any chlorine in it.The PH and ALK level is extremly high.I was using a chlorine floater and was shocking the pool and using a algae protector(everything was good).Last week it stormed everyday of the week.Had to take the pool cover off because it was caving in from all of the heavy rain.When I noticed all the levls was extremly off I went to the pool store.The man said do not use the floater and sold me powder chlorine.He also said not to shock the pool anymore because the powder chlorine will do that.He also sold me a liquid PH decreaser.He said to put in the pool when I got home,then today then tomorrow.I put the chemicles in yesterday.No change to all the levels but water clouded within a few minutes.Put more in today.Chemical level remained the same and water clouded more.Can hardly see bottom of pool,Suppose to put chemicles in tomorrow but they are only clouding the water.Before I started putting these chemicles in that he told me to.........................

2007-05-06 16:56:09 · 1 answers · asked by darlene100568 5

A glass vessel fitted with a stopcock has a mas of 337.428g when exacuated. When fillied with argon, it has a mass of 339.854g. When evacuated and refilled with a mixture of argon and neon, under the same conditions of temperature and pressure, it weighs 339.076g. What is the mole percent of neon on the mixture?

please explain.

2007-05-06 16:46:29 · 2 answers · asked by yvonll 2

2. ) Potassium hydroxide reacts with phosphoric acid in a neutraliztion reaction. Write the balanced chemical equation for this reaction. What volume of 4.00 M potassium hydroxide would be required to neutralize 67.8mL of 0.645 M phosphoric acid? Write the balanced chemical equation for this reaction. If 63.2mL of 1.48 M sodium hydroxide is required to neutralize a 82.5mL sample of vinegar, what is the molarity of the vinegar?



4.) A standardized solution of 0.065 M HCl is titrated w/ a saturated solution of calcium hydroxide to determine its molarity and its solubility. It takes 25.0 mL of base to neutralize 10.0mL of the acid. Write the balanced molecular equation




3.) Vinegar (HC2H3O2) reacts with sodium hydroxide in a neutralization reaction.

2007-05-06 16:39:57 · 1 answers · asked by Anonymous

A 5.00 gram sample of a dry mixture of potassium hydroxide, potassium carbonate, and potassium chloride is reacted with 0.100 liter of 2.00 molar HCl solution.
A 249 milliliter sample of dry carbon dioxide gas, measured at 22 degrees Celsius and 740 torr, is obtained from this reaction. What is the percentage of potassium carbonate in the mixture?
The excess hydrochloric acid is found by titration to be chemically equivalent to 86.6 milliliters of 1.5 molar sodium hydroxide. What are the percentages of potassium hydroxide and of potassium chloride in the original mixture?


I figured out the first part for th percentage of K2CO3 which is 27.6%, i think.

But I dont understand the second part. I know I started with .100 liters of 2.0 molar HCl solution(.200mol). And now the last part says i ahve an excess of HCL which is equal to .0866L of 1.50 Molars HCL (.130mol).

From there I dont know what I should do to get the percentages of KOH and KCl. Help please.

2007-05-06 16:39:36 · 1 answers · asked by Mario M 1

2007-05-06 16:35:10 · 4 answers · asked by wld_jkr 4

Sodium hydride reacts with excess water to produce aqueous sodium hydroxide and hydrogen gas. What mass(in grams) of sodium hydride wil produce 982mL of gas at 28.0°C and 765 torr total pressure, when the gass is collected above water? The vapor pressure of water at this experiment is 28 torr.


please explain in detail if you can. thanx

2007-05-06 16:32:22 · 1 answers · asked by yvonll 2

2007-05-06 16:15:11 · 3 answers · asked by phresh 1

Calculate the amount of energy released per gram of hydrogen nuclei reacted for the following reaction. The atomic masses are 11H, 1.00782 amu, 21H, 2.01410 amu, and an electron, 5.4858 10-4 amu. (Hint: Think carefully about how to account for the electron mass.)

2007-05-06 16:12:30 · 1 answers · asked by navi 2

Apparently they all are. I thought it was just the top 4 and not At. I am thinking of the rule of 7 (H, N, O, F, Cl, Br, and I are all diatomic). Is At diatomic too?

2007-05-06 16:06:45 · 5 answers · asked by Anonymous

And which of the following substances does not contain any covalent bonds?
Mg(PO4)2 (Magnesium phosphate)
NaHCO3 (baking soda)
NaBr (Sodium bromide)
NaNO3 (sodium nitrate)

2007-05-06 16:06:34 · 2 answers · asked by Heavy Metal 3

SiCl4, SeF4, XeF4, or POCl3 ?

2007-05-06 16:02:07 · 1 answers · asked by Red 2

When 0.150 g of liquid octane. C8H18 was burned in a flame calorimeter containing 1.500 kg of water, the temperature of the water rose from 25.246 degrees celsius to 26.386 degrees celsius. What is the standard enthalpy of combustion of octane at 25 degrees celsius?

2007-05-06 16:01:46 · 1 answers · asked by Anonymous

COuld someone please help? Thanks a bunch

To how much water should 50. mL of 12 M hydrochloric acid be added top produce a 4.0 M solution?

I have no clue where to start from. Im guessing 50 mL is the V1 and 12 M is M1 and 4.0 M is M2 but what do i do?
Could you please show how to do this problem. Thanks a bunch.

Thanks a bunch to who help me really appreciate it.

2007-05-06 16:01:34 · 2 answers · asked by sk8er_ace23 1

I am trying to find a manufacturer, agent, or the like who can help me source balls made from foam latex, they need to be 100mm in diameter and have a bounce of at least 50% when dropped from 1 mtr. If anyone can help i can provide far more detail as required. Even though i am prepared to buy a great number of these on an ongoing basis i just cannot find anyone who can make them for me.

2007-05-06 16:00:29 · 1 answers · asked by Anonymous

2007-05-06 15:53:52 · 1 answers · asked by bobo 2

. Consider the following equation:
N2 + 3 H2 ® 2 NH3

How many moles of hydrogen are required to react with 3.4 moles of nitrogen to form ammonia fertilizer?


3.4 moles hydrogen
10.2 moles hydrogen
1.13 moles hydrogen
not enough information is given


Which of the following situations represents an increase in entropy (positive entropy change)?
Hot water cooling
snow melting
sugar water crystallizing
water freezing

2007-05-06 15:47:41 · 1 answers · asked by Heavy Metal 3

Note: All "2"'s below are subscripts.
CH2CH2
N2
H2O
CH2F2

2007-05-06 15:26:45 · 4 answers · asked by Heavy Metal 3

Manganese ion
Manganese (II) ion
Magnesium ion
Magnesium (II) ion

2007-05-06 15:24:27 · 3 answers · asked by Heavy Metal 3

A hard, whitish substance that looks a bit like quartz.
A substance that conducts electricity upon dissociation .
A powdery substance that melts easily on your stovetop.
A solid that dissolves easily in water.

2007-05-06 15:20:30 · 2 answers · asked by Heavy Metal 3

I'm having trouble predicting the products for this reaction. Sodium Hydroxide is added to Propionic acid and this is what I've got so far:

NaOH (aq) + CH3CH2COOH (aq) -------> NaC3H5O2 (aq) + H2O (l)

I think the products are wrong because the equation comes out perfectly balanced which...really shouldn't be? Any help on this would be appreciated. Thanks.

2007-05-06 15:15:36 · 1 answers · asked by Tevina 2