Tuesday
December 6, 2016

Posts by DrBob

Total # Posts: 12

chemistry
density = mass/volume and (V1/T1) = (V2/T2) Reason it out.
September 14, 2016

AP Chemistry
pH = -log(H^+). Substitute and solve for (H^+). That will be the molarity in mols/L.
September 14, 2016

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...
September 14, 2016

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
September 14, 2016

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...
September 14, 2016

chemistry
You should learn how to write arrows. Answer is D.
September 14, 2016

chemistry
A is the best answer here. However, it isn't always true. Much depends upon how acids and bases are defined.
September 14, 2016

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 ...
September 14, 2016

Physics
work by conveyer belt = work of normal + work of friction force why i don't know its dumb.
July 14, 2013

Physics
sloppy work henry
July 14, 2013

chem 121
NaCl is a solid. CH4 is a gas. The last one is a liquid. That should be enough of a hint.
July 9, 2010

Science
Don't second guess yourself.
December 8, 2006

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