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# So the chem II....

## Replies to: So the chem II....

• Registered User Posts: 855 Member
I'll try to add a question.

which of the following shows the wavelength of electromagnetic waves in INCREASING order?

a. x-ray, gamma ray, infrared, microwave
b. visible, infrared, microwave, radio wave
c, ultraviolet, visible, x-ray, gamma
d, radiowave, visible, ultraviolet, x-ray.

Don't think that'll be tested, but it's B. (oh wait, that was already answered)

I'll add a question

How much HCl must be added to neutralize 0.01 L of 1M Ca(OH)2?

A. 0.001 mol
B. 0.01 mol
C. 0.02 mol
D. 0.03 mol
E. 1.00 mol
• Registered User Posts: 312 Member
Use stoichiometry (hard to write on this but let me try)

0.01L x (1 mol Ca(OH)2 / 1000 mL ) x (2 mol OH- / 1 mol Ca(OH)2) x (1 mol H+ / 1 mol OH-) x (1 mol HCl / 1 mol H+ )

All this should = 0.02
• Registered User Posts: 765 Member
yeah since theres an 2OH then just multiply its M by 2
• Registered User Posts: 312 Member
wow that's easier lol
• Registered User Posts: 1,780 Senior Member
Don't you have to know the concentration of the HCl to do that problem or is it just assumed to be 1M?
• Registered User Posts: 1,966 Senior Member
At standard conditions it is 1 M, but they usually would say 1 M anyway.
• Registered User Posts: 595 Member
The answers are in moles so you don't need concentration.
• Registered User Posts: 1,966 Senior Member
Umm, yes you do. If it says 0.01L of HCL, then you'd be like what? You can't find the number of moles without the volume and molarity.
• Registered User Posts: 595 Member
Umm no you don't need molarity... you know how many number of moles you need to neutralize 0.01 moles of Ca(OH)2, which is 0.02 moles, and the answers are in moles. If they asked you for the volume then you'd need concetration, but the answers are already in moles.
• Registered User Posts: 1,966 Senior Member
Oh, sorry again. I meant M for Ca(OH)2.
• Registered User Posts: 595 Member
Haha I see :] Better read carefully on the actual test!
• Registered User Posts: 1,780 Senior Member
Suddenly, everything makes sense. (About what you said, I mean, I<3Pi.)
• Registered User Posts: 765 Member
if it were NaOH instead of Ca(OH)2, the answer would be .01, correct?
• Registered User Posts: 828 Member
yup .
• Registered User Posts: 595 Member
Correct :]
This discussion has been closed.