Chemistry - April 2007

This is a long confusing problem. Mr. H has been told by his superiors that only a chemist can be trusted with the combination to a safe. The combination is the pH of solution A, described bellow, followed by the pH of solution C (for example: If the pH of solution A is 3.47 and that of solution C is 8.15, then the combination to the safe is 3-47-8-15). The chemist must determine the combination using only the information below (all solutions at 25 degrees Celcius).

1) Solution A is 50.0 mL of a .100 M solution of the weak monoprotic acid HX.
2) Solution B is a .0500 M solution of the salt NaX. It has a pH of 10.02.
3) Solution C is made by adding 15.00mL of 0.250 M KOH to solution A.

What is the combination to the safe?


This is really confusing. I have no idea where solution B even came from or what the heck I'm supposed to do with it!! HELP!!!

2007-04-29 06:10:46 · 3 answers · asked by ananymous 1

...when the molar mass & density are almost identical?

2007-04-29 06:08:29 · 2 answers · asked by Dee Dee 2

The equation is Mg(OH)2 + 2HCl -> MgCl2 + 2H2O.

please help! also, can i see how you worked this problem out as well? thanks!

2007-04-29 05:48:44 · 2 answers · asked by soccrrulz21 2

What is the formula?

2007-04-29 04:19:18 · 1 answers · asked by moon r 2

If a 500L indoor air sample with a mass of 0.59kg contained, 3.2mg of formaldehyde, what would be the concentraction of formaldehyde in parts per million?

2007-04-29 03:24:19 · 1 answers · asked by no name 1

An element with the electron configuration [noble gas] ns2(n - 1)d10np2 has ____________ valence electrons.



a. 10

b. 16

c. 4

d. 2

2007-04-29 03:07:15 · 3 answers · asked by Anonymous

In the Lewis symbol for a fluorine atom, there are __________ paired and __________ unpaired electrons.

a. 4, 2
b. 4,1
c. 2, 5
d. 6, 1
e. 0, 5

2007-04-29 02:26:10 · 5 answers · asked by pthrb5 1

Do s, p, d and f stand for something? I read that they denote the names of some orbital. Kindly clarify.

2007-04-29 01:47:26 · 3 answers · asked by akshay 2

Is there a test for tertiary alcohols which doesn't involve oxidation - which just says that the liquid is not primary or secondary . This result may mean that it, as well as being a tertiary, can be anything that doesn't oxidise right?

2007-04-29 01:41:42 · 1 answers · asked by Anonymus 2

Could some one either give me the equation for a reaction of an alcohol and Chromic Anhydride in Sulphric acid? or a differnt reaction to find the presens of an alcohol in a substance. i know there are lots but my mind is blank... any help?? thanxs

2007-04-29 01:39:29 · 1 answers · asked by Genesis 2

I was doing an experiment to find the stoichiometric ratio ( HCL/NaOH). I had to mix 3.0M of HCl with water, so the molarity would decrease to 1.0M and I had to wait for a few minutes until both of the solutions (HCL & water) came to the same temperature. Why was it important to wait until the solutions to be mixed had come to the same temperature?
Thank you!

2007-04-28 23:42:48 · 2 answers · asked by pucchihime 1

the preparation of nylon is carried outwith two solvents that do not dissolve in each other with one starting material in each of the solvents. the reaction occurs at the interface of the two solvents. why is it carried out in this way? what would the result e if one solvent that dissioved both reagents were used instead?

2007-04-28 23:40:25 · 1 answers · asked by Anonymous

2007-04-28 22:37:12 · 2 answers · asked by arastu u 1

any ideas/help?

2007-04-28 22:11:47 · 4 answers · asked by thevendingmcahine 2

Reaction N2(g) + 3 H2(g)>>>2 NH3(g)

2007-04-28 21:21:17 · 3 answers · asked by Anonymous

thank u 4 answering my previous questions... i have two more... what happens when the following are added with 0.1 M HCl: iron filings in a test tube and Mg ribbon in a test tube? what type of change do they undergo? how about when added with FeCl3? what type of change do they undergo? thank u very much.

2007-04-28 21:16:34 · 3 answers · asked by Anonymous

what happens when you heat food color powder in a test tube? is that a cemical change? salt pops in a test tube upon heating. is that a chemical change? pls help me A.S.A.P...

2007-04-28 21:03:12 · 3 answers · asked by Anonymous

concentrated sulfuric acid is added to potassium iodide.
what r the half equations?
and also the overall equations?

i assumed that I2 and SO3/2- ions are the products of the reaction between sulfuric acid and potassium iodide.

i couldnt work it out though
any help please??

2007-04-28 20:55:36 · 1 answers · asked by mayeham7 1

I need an answer to this question, but could you PLEASE provide an explanation? I really need to understand this!

Thanks!

2007-04-28 20:34:16 · 6 answers · asked by 1two3 1

10.0 grams of Al and 19.0 grams of O2? Reaction: 4Al + 3O2 >>>2Al2O3

2007-04-28 20:31:58 · 5 answers · asked by Anonymous

triple bond, lone pair of electrons, a double bond, a single bond, all of them

2007-04-28 19:51:45 · 1 answers · asked by julie r 1

Calculate the final pressure of gas in atm.

2007-04-28 17:53:14 · 4 answers · asked by Katy J 1

Given the unbalanced equation: NaNo3-------NaNo2 + O2

2007-04-28 17:49:20 · 2 answers · asked by Katy J 1

Si...S...Cl...Al...or...None

2007-04-28 17:39:38 · 3 answers · asked by dman 1

CCI4...NH3...SiO2...All...or None?

2007-04-28 17:36:55 · 4 answers · asked by dman 1

Another review question I'm having trouble on...

During B(beta)-oxidation, methylene (-CH2-) groups in the fatty acid are oxidized to carbonyl (C=O) groups, yet no oxygen is consumed by the reactions of B(beta)-oxidation. How is this possible?

2007-04-28 17:17:48 · 3 answers · asked by vikman3001 2

If I'm dissolving a certain amount of Potassium Nitrate in water at a certain temperature, how can I find out the exact amount of solute (i.e. Potassium Nitrate). Something other than adding a lot of the compound and measuring the excess that is left behind.

2007-04-28 16:54:56 · 3 answers · asked by foundation 3

How long will it take for 99.9% of a 0.00310 mg sample of radioactive chromium-51 to decay? The half-life of chromium-51 is 27.80 days, so give your answer in days.

Enter a numeric answer only do not include units

2007-04-28 16:53:30 · 1 answers · asked by owaifkahlfkjh 2

Any1 know who uses the Janet periodic table? Nid 4 Project.

2007-04-28 16:49:42 · 2 answers · asked by alvin t 1

I mean, how do you get the moles if you don't know the volume?
Let's say, for example:

0.008 M NaOH and 0.01 M HBr. How would you find the equivalence point?

2007-04-28 16:29:14 · 3 answers · asked by Anonymous