Chemistry - September 2006

If characoal and sugar were impurities present in a sample of impue benzoic acid, explain how the recrystallisation from water would remove both ?

2006-09-26 06:26:57 · 3 answers · asked by Anonymous

Calculate the final temp of 245 ml of water initially at 32 degrees C upon absorption of 17 Kj of heat. and explain how you did it please! Thanks

2006-09-26 06:22:45 · 5 answers · asked by Angel Eve 6

How many electrons are transfered from a magnesium atom to each bromine atom in the formation of magnesium bromide?

2006-09-26 06:20:52 · 3 answers · asked by k 8710 2

You know, for the chemistry and calculus classes you had to take in 1st or second year college? Or would it be better to get a high school guide for simplicity? I'd like to get one that spells everything out in the most basic terms and then gives "whys" and practical examples. Any suggestions of stuff that helped YOU?! Thanks!

2006-09-26 06:14:36 · 5 answers · asked by JillyJilly2x4 2

why is that solutions for ion analysis, especially dilute solutions, should always be stored and measured in plastic, rather than glass containers

2006-09-26 05:16:36 · 3 answers · asked by Anonymous

and if a radioactive element like urainium could be used would it's radioactive properties be present in the laser beam?

2006-09-26 05:15:47 · 2 answers · asked by bill_armstrong@sbcglobal.net 1

K[Co(C2O4)2(H20)2] all of the numbers are lower case

[Fe(NH3)2(NO2)2]2SO4 all of the numbers are lower case

2006-09-26 04:59:46 · 3 answers · asked by nedjine05 1

You are given a gaseous substane which boils at -161 degrees celcius. It is flamable and can be used as fuel. Is it a covalent compound? Do you expect this substance to conduct electricity in the liquid state? Justify your answer.

2006-09-26 04:19:06 · 6 answers · asked by killer 1

Edit.. periodic table and beyond?

2006-09-26 04:15:58 · 4 answers · asked by killer 1

2006-09-26 03:35:08 · 6 answers · asked by white d 1

2006-09-26 03:16:32 · 13 answers · asked by Anonymous

why two different compounds can't have same molecular formula?

2006-09-26 03:13:06 · 9 answers · asked by aswin r 1

2006-09-26 02:52:48 · 12 answers · asked by chha 1

1: Which substance is readily converted from a liquid to a solid by chemical reaction with hydrogen?
cotton-seed oil

glycerin

kerosene

mercury


2: The ability of a substance to remove oxygen from a compound is called
oxidation

hydrogenation

electrolysis

reduction


3: When passed over hot copper oxide, hydrogen acts as
a catalyst

X an oxidizing agent
a reducing agent

a solute


4: Hydrogen can be prepared by reacting cold water with
aluminum

iron

platinum

X sodium

5: The safest way to make hydrogen in the laboratory is to add hydrochloric acid to
calcium

iron

potassium

sodium


6: Hydrogen may be formed when steam reacts with hot
copper

X iron
mercury

silver


7: The lightest element known is
boron

helium

hydrogen

lithium


8: Hydrogen is
less dense than air and inert

very soluble in water and combustible

odorless and a reducing agent

denser than air and tasteless


9: Hydrogen may be obtained by the reaction of hydrochloric acid with
copper

mercury

silver

zinc


10: When copper oxide is heated with hydrogen, which substance is oxidized?
X copper
copper oxide

hydrogen

water


11: Uncombined hydrogen is found in
soda water

acids

hydrogen peroxide

water gas


12: When hydrogen and oxygen are mixed
they explode

they combine forming water slowly.

they form hydrogen peroxide.

they form an explosive mixture.


13: Hydrogen was discovered by
Preistly

Scheele

Lavoisier

Cavendish


14: In the preparation of hydrogen in the laboratory the acid used is added through the
delivery tube

thistle tube

trough

collecting bottle


15: Hydrogen is used:
to support burning

as part of fuel gas

as an explosive

as a cooling agent


16: If lead oxide is heated in a stream of hydrogen, the products will be
lead hydride and oxygen

lead and water

lead oxide and hydrogen

lead oxide and water


17: A cold piece of iron was held over a Bunsen flame. Droplets of water collecting on the cool surface indicated that the fuel contained
carbon

carbon dioxide

carbon monoxide

hydrogen


18: Helium rather than hydrogen is used in dirigibles because
it is lighter than hydrogen

it is insoluble

it is cheaper

it does not burn


19: If an explosion results from placing a burning splint into a bottle of gas, the gas may have been
oxygen

carbon dioxide

hydrogen

nitrogen


20: The removal of oxygen from a compound is called
oxidation

hydrogenation

reduction

filtration


21: Holding a bottle of hydrogen inverted and without a cover plate indicates that hydrogen
is a gas

is heaver than air

is lighter than air

is soluble in water


22: In the process of reduction, whenever one substance is reduced, another is
hydrogenated

oxidized

aerated

condensed

2006-09-26 02:10:53 · 5 answers · asked by Anonymous

Amino acid are often esterified with methanol by using thionyl chloride or hydrogene chloride as catalist. Did you know if an important amount of methylchorid is formed ?

2006-09-26 02:07:50 · 4 answers · asked by schneiderj 2

2006-09-26 01:58:25 · 12 answers · asked by Gun Du 1

2006-09-26 01:43:30 · 14 answers · asked by rachel v 1

2006-09-26 01:36:17 · 5 answers · asked by jhaziel o 1

Took urine drug test yesterday, and not sure doctor believed me when I told him I had been taking the original hydrocodone prescription recently rather than his "upped" script for oxycodone. (The oxy stuff was making me sick). Will the drug screen support my claim, or will the doc just know that I am taking pills for pain?

2006-09-26 00:53:38 · 5 answers · asked by spineminus2 3

2006-09-26 00:52:06 · 12 answers · asked by ÅñÑã 1

2006-09-26 00:51:58 · 2 answers · asked by jhaziel o 1

2006-09-26 00:13:26 · 15 answers · asked by Anonymous

i'm a college student of 21 yrs. i had affair with my uncle.

2006-09-26 00:02:29 · 9 answers · asked by manju sweety 1

2006-09-25 23:34:20 · 7 answers · asked by exceptional402000 2

Does anyone know the enzyme activity of lactate dehydrogenase, malate dehydrogenase and succinate dehydrogenase?
Please include scource too.

2006-09-25 21:24:08 · 2 answers · asked by Who_am_i 1

2006-09-25 19:58:34 · 3 answers · asked by amoure j 1

chemical properties?

the question is which of these pairs do the two species resemble each other most closely in chemical properties?

a. 1..............1.. +
.....H... and... H
....1..............1

b..14........... 14.. 3-
......N... and... N
.....7............. 7

c. ..12 ........13
........C and .. C
.......6 .......... 6

my guess is C because the electron charge is the same so any chemical reaction would react based on the electrons... but i was hoping i could get some insight to this question?

2006-09-25 19:22:40 · 8 answers · asked by misterlyle 3

2006-09-25 19:19:51 · 12 answers · asked by kenshin_kudo 1

2006-09-25 18:25:50 · 4 answers · asked by Anonymous

Please provide answers that sound professional-like.

2006-09-25 17:20:08 · 5 answers · asked by Anonymous