Chemistry - November 2007

9. A centimeter is what part of a meter?
1
1/10
1/100
1/1000
unable to determine

10. In chemistry how do we deal with the atomic mass unit (amu)?
substitute grams/mole for amu and round to the nearest tenth decimal place
substitute grams/mole for amu and round to the nearest one decimal place
substitute mole/gram for amu and round to the nearest tenth decimal place
substitute mole/gram for amu and round to the nearest one decimal place

11. Which piece of equipment would you choose to most accurately measure 25.0 ml of water?
a graduated cylinder
a beaker
a thermometer
a test tube

13. What is the density of an object having a mass of 8.0g and a volume of 25cm3?
(*Hint mL = cm3)
0.32 g/cm3
2.0 g/cm3
3.1 g/cm3
200 g/cm3
none of the above

2007-11-13 08:01:28 · 6 answers · asked by emando16 2

3. Solve with correct significant figures: (3.08 x 10-3) x (4.90 x 10-7) =
1.51x10^10
1.5x10^9
1.5x10^10
1.51x10^9


4. Convert to moles: 3.50 g CaO:
.0625
196
1.75
3.50

5. Mole:
Quantity of a substance (6.02 x 1020) that has units of grams/mole
Quantity of a substance (6.02 x 1043) that has units of grams/mole
Quantity of a substance (6.02 x 1022) that has units of grams/mole
Quantity of a substance (6.02 x 1023) that has units of grams/mole


6. How many moles are there in 24.0 grams of carbon?
2.0
2.2
2.22
2.3


7. How many grams are there in .50 moles of carbon dioxide, CO2?
22
222
202
2.2

2007-11-13 07:59:09 · 1 answers · asked by emando16 2

What I know:
vol of hydrogen peroxide sample is 8.72ml
mass of hydrogen peroxide sample is 8.72g
barometric pressure in lab is 764.29 mm HG
temp in lab is 21 celcius
vol of oxygen gas collected is 99.4 mL

1) How many moles of oxygen were collected
n= .0821 x 284 divided by 1atm x 99.4 mL
n=.23 moles

that doesnt seem right :(

2) using the balanced equation (there is twice as much h202 needed as o2 produced). What is the molarity of the hydrogen peroxide solution?
It would be double my answer in #1, but i dont think that answer is right

3) what is the mass percent hydrogen peroxide if the density is 1.00g/ml

4) calculate the volume of oxygen gas that would be produced upon the decomposition of 10ml of 30%(m/m) aqueous hydrogen peroxide solution. Assume the gas is collected at 1atm and 25 degrees celcius and density of hydrogen peroxide is 1.11g/mL.

2007-11-13 07:57:48 · 2 answers · asked by shirah d 2

Okay, so I want to know where I can find out what the lewis dot or vsepr model for the following molecules:

RnF2
SiI42- that's Silicon Iodide with a subscript 4 and then superscript 2-
KrO3
AlCl4-

Or if you know how to do the lewis dot structures, then that would be really great or if you can explain them to me would be just as good. thank you

2007-11-13 07:41:07 · 2 answers · asked by naknoi 5

2007-11-13 07:30:34 · 1 answers · asked by leaudocean 1

1. What are the signs (positive or negative) of q (heat) and w (work) for the following exothermic process at P=1 atm and T=370K
H2O(g)-->H2O(l)
I know q is negative for exothermic rxns, but I'm not sure whether w is positive or negative.

2. Using the following data, calculate the standard heat of formation of the compound ICl (g) in kJ/mol
Cl2(g) --> 2Cl(g) ∆H° = 242.3kJ
I2(g) --> 2I(g) ∆H° = 151.0kJ
ICl(g) --> I(g) + Cl(g) ∆H° = 211.3kJ
I2(s) --> I2(g) ∆H° = 62.8kJ

I came up with 16.75kJ, but could someone double check the answer?

2007-11-13 06:47:54 · 1 answers · asked by S281 2

2007-11-13 06:11:39 · 2 answers · asked by Anonymous

It would be wonderful if you can solve it here so that I can learn. The molar mass is 270.0g/mol.

2007-11-13 05:55:43 · 2 answers · asked by Sijal A 1

What is the product when m-nitroacetaphenone is treated with NaBH4 in ethanol?

I cant figure out what the forumla for the product is. Any help would be great.
Thanks

2007-11-13 05:38:52 · 2 answers · asked by Anonymous

anyone know how to convert 64.04 ppm to mg/L?

2007-11-13 05:28:20 · 5 answers · asked by Justin 2

I want this info to create food (CO2) in an aquarium with algae.

How many grams of CO2 are released?

2007-11-13 04:14:13 · 1 answers · asked by espiral 2

2007-11-13 03:47:20 · 3 answers · asked by okrusoup 2

Sorry I'm doing homework, and confuzzled lol.

2007-11-13 03:28:32 · 4 answers · asked by Anonymous

2007-11-13 02:52:00 · 1 answers · asked by Anne 1

In the Lewis-Dot structure of NF, would N double bond to F?

2007-11-13 02:49:34 · 4 answers · asked by Ashley 2

A) Sn2+
B)Au+
C)Zn2+
D)N3-
E)Se2-
F)Br-
G)Ba2+
H)In3+
I) F-

2007-11-13 02:33:42 · 4 answers · asked by Anonymous

2007-11-13 01:19:49 · 13 answers · asked by Anonymous

Explosive charges containing TNT (trinitrotoluene) do not explode when subjected to mechanical shock, but they do explode violently when detonated properly. The most common type of detonator is a blasting cap containing mercury fulminate, Hg(CNO)2, which does explode when struck. Draw the correct Lewis structure for the CNO- anion, and for the optimum structure decide which of the following statements about formal charge are true. Enter the correct choices in alphabetical order, e.g. ACF, ABDF, etc.
A) FCC=0
B) FCC=+1
C) FCC=-1
D) FCC=-3
E) FCN=-1
F) FCN=+3
G) FCN=0
H) FCN=+1
I) FCO=-1
J) FCO=-3
K) FCO=0
L) FCO=+1

Thank you!

2007-11-13 01:19:00 · 3 answers · asked by Anonymous

2007-11-12 23:14:59 · 3 answers · asked by ndrspooner 1

Follow the description of the reaction below and answer the question following it:

In a dry cell battery the reaction that releases energy is: metallic zinc reacts with ammonium chloride to form zinc (II) chloride and ammonia (NH3) and Hydrogen gas.

a. Write a balanced equation for the reaction.

b. What is the ratio of number of moles of ammonia produced: number of moles of zinc consumed?

c. Calculate the mass of ammonia released when 32.84 g of Zinc are consumed

2007-11-12 20:03:44 · 4 answers · asked by Anonymous

I need it badly, I used to search all-over the net. However, some sites said that it can produce electricity while some sites said that it has no capability.

2007-11-12 19:45:38 · 2 answers · asked by jayveelim1323 2

1) What masses of Iron (III) Oxide and aluminum must be used to produce 15 g of iron? What is the maximum mass of aluminum oxide that could be produced?

Fe2O3 + 2AL ---> 2Fe + Al2O3

2) When aluminum burns in bromine, aluminum bromide is produced. In a certain experiment, 6.0 g of aluminum was reacted with an excess of bromine to yield 50.3g aluminum bromide. Calculate the theoretical yield and percentyield for this experiment.

Need explanation please!

2007-11-12 19:10:57 · 1 answers · asked by Someguy25 4

1. The total volume of hydrogen gas needed to fill the Hindenburg was 2.00 x 10^8L at 1.00 atm and 25.0°C. How much energy was evolved when it burned?

2. What are the signs (positive or negative) of q (heat) and w (work) for the following exothermic process at P=1 atm and T=370K
H2O(g)-->H2O(l)

Then one problem using Hess' Law, I can't get it to work out correctly:

3. Using the following data, calculate the standard heat of formation of the compound ICl (g) in kJ/mol
Cl2(g) --> 2Cl(g) ∆H° = 242.3kJ
I2(g) --> 2I(g) ∆H° = 151.0kJ
ICl(g) --> I(g) + Cl(g) ∆H° = 211.3kJ
I2(s) --> I2(g) ∆H° = 62.8kJ

2007-11-12 18:26:59 · 1 answers · asked by S281 2

Elemental ananalysis of a compound results in the following data
65.45 % C
5.49 % H
29.06 % O
4.13 g of the compound fills a 187.0 ml bottle with a pressure of 2455.8 mm Hg at a temperature of 21.4oC. What is the molecular formula of this compound ?

2007-11-12 17:38:57 · 2 answers · asked by starrynight4592 1

I am not sure on how to measure the rust on nails. Is it possible to scrape the rust off and measure the rust on a scale? Also does the weight of a nail increase or decrease when rust forms on it?

2007-11-12 17:19:50 · 3 answers · asked by Anonymous

2007-11-12 17:16:11 · 6 answers · asked by broken_lies14 2

I have an aluminum sample of 1.5grams which i calculated to .055 moles. What is the minimum volume of 3.0 M (molar) KOH that would be required to react with this mass of Al?

KOH and Al have a 1:1 mole ratio

2007-11-12 15:58:14 · 2 answers · asked by Anonymous

I'm in 1oth grade and need it for high shool chemistry homework..help please?
I know tin is Sn so what is nitride?

2007-11-12 15:49:52 · 5 answers · asked by zahyra33 2

2007-11-12 15:35:35 · 3 answers · asked by Chris T 1

Br2
PCl3
LiCl
CiF
MgCl2

2007-11-12 14:35:11 · 4 answers · asked by jamie d 2