Posts by DrBob

Total # Posts: 21

Science
Frankly, I don't like any of them.

Chemistry
I can't give you a link but go to google and type in that word. You will gt plenty of information. Basically you take a triacid (such as stearic acid) and neutralize it with NaOH or KOH. The product is soap. That stuff is tough on the skin unless it's washed thoroughly...

Science
yes

Algebra
tax = 77 x 0.063 = ? Total = 77 + ? = xx I agree with your answer.

CHEMISTRY
You have 25.0 mL x 1.00 M = 25 mmols or 0.025 mols HBr and KOH reacting. How much heat is generated? q = mcdT. m = mass = 25 + 25 = 50 grams. c = 1 cal/g. dT = delta T = 31.4-24.5 = 6.9 degrees.so q = 345 cal per 0.025 mols. How much is that for 1 mol? Remember this is an ...

Chemistry
That's a typo. It should be -13.8 kcal/mol. See above under post by Tom for my response.

Chemistry
See post above with Tom.

Chemistry
I answered this above. The answer of -14.8 kcal/mol is correct.

chemistry
density = mass/volume and (V1/T1) = (V2/T2) Reason it out.

AP Chemistry
pH = -log(H^+). Substitute and solve for (H^+). That will be the molarity in mols/L.

AP Chemistry
That's perfectly ok. You aren't plugging it in right. On my calculator, if you hit the 10^x key then -7, you get the answer of 1E-7. If you're going the other way (that is, given (H^+) = 1E-7, and you want the pH), then hit the log button, type in 1E-7 and you will...

AP Chemistry
Acids have pH = 0 to pH = 7 so pH = -log(H^+). pH 0 then (H^+) = 1 x 10^0 pH 7 then (H^+) = 1 x 10^-7

Gateway
I can tell you that you do not make oxygen by heating MgO. You make MgO by heating Mg and O2. However, in the spirit of the question, I will answer as written. This is the Law of Conservation of Mass. You started with 10 g so you must end up with 10 g. .....MgO ==> Mg + O2...

chemistry
You should learn how to write arrows. Answer is D.

chemistry
A is the best answer here. However, it isn't always true. Much depends upon how acids and bases are defined.

chemistry
I don't like any of the answers but the best one here is A. NaCl dissolves in water because the NaCl crystal is surrounded by H2O molecules with the O end attracted to the Na ion and the H end attracted to the Cl ion. That attraction breaks the lattice energy of the NaCl ...

Physics
work by conveyer belt = work of normal + work of friction force why i don't know its dumb.

Physics
sloppy work henry

chem 121
NaCl is a solid. CH4 is a gas. The last one is a liquid. That should be enough of a hint.

Chemistry
You're Welcome :)

Science
Don't second guess yourself.