***Chemistry - Fall 2005***

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Who else is taking Chemisrty this semester? I thought maybe we can check in with each other, and help each other out.

If there is enough of us maybe we can even get a sticky.

I am taking Health Science Chemistry 1.

:rotfl: Help! Ok, I have 3 problems I just can not figure out.

1. A sample of lead shot weighing 343.6 g was added to a graduated cylinder partially filled with isopropyl alcohol (enough to immerse the lead completely). As a result, the alcohol level rose 30.3 mL. What is the density of the lead in SI units? (the density of isopropyl alcohol is 0.785 g/cm3)

2. The RDA of calcium is 1200mg. Calcium carbonate contains 12% calcium by mass. How many grams of calcium carbonate are needed to provide the RDA of calcium? Honestly- I know the answer is 10 g but I can not tell you how to get the answer.

3. An office is 4.44m long, 3.48m wide, 2.53 m high. The avg density of air is 1.29 X 10 (exp -3). What is the mass (in kilograms) of the air in the office?

Any help would be great. Thanks guys.

The 1st problem is a tricky one. I could be wrong but it seems that the density of the Isopropyl may not matter but the mass of the lead along with the displacement of isopropyl matters. So, d= m/v= 343.6g/30.3mL

I think you're right on the answer for the 2nd problem but I'm not sure how to set it up. I mean 1.2g Ca/.12 Ca = 10g Ca

In the 3rd problem, I believe you can use the density forumla to get the answer. I would first take the dimensions given and convert them to cm and then multiply all three of the values and you should have your volume.

So, 444cm x 348cm x 253 cm = 3.91 x 10^7 cubic cm or mL.

Ok, now we're going to have to rearrange the density formula to get the mass.

d=m/v becomes d x v = m so, 1.29 X 10^-3 g/cubic cm X 3.91 x 10^7 cubic cm =50439 g.

Convert the mass into kg=50.4g.

Man, I hope that's right. Sorry if I'm way off base!

(I forgot to sign on under my own screen name, which is Soleilpie. So please don't get mad at Moonepie, if I totally don't know what I'm talking about! :)~ )

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Specializes in Operating Room.

That's another thing I need to practice on b/4 Wednesday. I think I have the formulas down.

So, hopefully I'll be able to catch on with the problems.

Accelerated classes are a pain sometimes! lol

OK, it's late (or early)... almost 3AM here. I've studied enough....nite or g/m .... lol

The 1st problem is a tricky one. I could be wrong but it seems that the density of the Isopropyl may not matter but the mass of the lead along with the displacement of isopropyl matters. So, d= m/v= 343.6g/30.3mL

I think you're right on the answer for the 2nd problem but I'm not sure how to set it up. I mean 1.2g Ca/.12 Ca = 10g Ca

In the 3rd problem, I believe you can use the density forumla to get the answer. I would first take the dimensions given and convert them to cm and then multiply all three of the values and you should have your volume.

So, 444cm x 348cm x 253 cm = 3.91 x 10^7 cubic cm or mL.

Ok, now we're going to have to rearrange the density formula to get the mass.

d=m/v becomes d x v = m so, 1.29 X 10^-3 g/cubic cm X 3.91 x 10^7 cubic cm =50439 g.

Convert the mass into kg=50.4g.

Man, I hope that's right. Sorry if I'm way off base!

(I forgot to sign on under my own screen name, which is Soleilpie. So please don't get mad at Moonepie, if I totally don't know what I'm talking about! :)~ )

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Ok, someone needs to learn me something...LOL

CuMnO4

Is it Copper Monomanganese tetraoxide, I'm thinking not.

Is it something totally different? The three elements are confusing me.

Copper and Manganese are transitional metals, and Oxygen is 2-.

And another:

RhSiO3

Rh is Rhodium, a transition metal.

Si is +/- 4

O is -2

And yet another question:

For compounds such as In2S3 is it:

diindium trisulfide

or

indium trisulfide

or

indium sulfide

AND.....how do you know whether or not to use the prefixes mono, di, tri, tetra, penta, hexa, hecto, octo, nano, or deca? I know beginning ones do not need mono, but the others are confusing me.

Are you suppose to use them all the time, or for an exact cross over such as In2S3, do you just use Indium Sulfide. (Indium is +3, and Sulfur is -2)

Thanks a bunch to anyone that can help!! :)

We are starting this is class on Wednesday. Sounds good and confussing:uhoh21:

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Specializes in Operating Room.
We are starting this is class on Wednesday. Sounds good and confussing:uhoh21:

I had it down in class when we learned it Wednesday, but had stuff to do to get ready for my daughter's bday part, which was yesterday. Thursday I went to tutoring to do the extra credit homework, and relearned it. lol

Then of course I have been busy trying to learn the polyatomics, ex: (PO4 ^3-) = Phosphate or NO2- = Nitrite. (^ = superscript, the ^ symbol is not used really, but just for this post)

I came up with a way to remember the equations for density, etc.:

Men = Venereal Disease! LOL (sorry to all men lol) Mass=Volume X Density

D=M/V (Dodge = Motor Vehicle) and

V=M/D (Vaccinations = Medical Doctor)

I know that Men= Venereal Dz (M=VD) is the only multiplication problem, so the others are division. :)

(Hope this helps someone too!)

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Thanks Moonpie. I now have the answers. This is what they are: The first one is 11.3 kg/m3- I don't understand why it is kg/m3 instead of g/mL - Do you?, The next one was set up just as you had it 1.2/.12 = 10g, The next one came out close to your answer, it was 5.04 x 10 (exp -5). I am going to go in early or check with the tutoring lab for some extra help. Luckily we are still on chapter one so I am going to try and stay on top of things.

Fun2care - Thank you for your memorization techniques. I actually have no problem with remembering things like that. My concern is taking the word problems and actually trying to figure out how/if to plug them in to the equation and when you bring in the exponents do they remain negative depending on where they are? I have so many questions I can not wait to go back to class and have them answered. I am so glad you are all here. It's nice to see the posts of people who are ahead along with the answers I am sure they will help all of us.

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Specializes in Operating Room.

kg and m3 are SI measurements, g/mL (or cm3 or cc) are metric.

The answer 11.3 kg/m3 is written in Standard International units, not metric.

Hope this helps. :)

Oh, and I love memorization techniques, especially when I'm trying to learn nursing converstions at the same time.....don't want to get minims and drams mixed up with mass and density. LOL

Thanks Moonpie. I now have the answers. This is what they are: The first one is 11.3 kg/m3- I don't understand why it is kg/m3 instead of g/mL - Do you?, The next one was set up just as you had it 1.2/.12 = 10g, The next one came out close to your answer, it was 5.04 x 10 (exp -5). I am going to go in early or check with the tutoring lab for some extra help. Luckily we are still on chapter one so I am going to try and stay on top of things.

Fun2care - Thank you for your memorization techniques. I actually have no problem with remembering things like that. My concern is taking the word problems and actually trying to figure out how/if to plug them in to the equation and when you bring in the exponents do they remain negative depending on where they are? I have so many questions I can not wait to go back to class and have them answered. I am so glad you are all here. It's nice to see the posts of people who are ahead along with the answers I am sure they will help all of us.

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kg and m3 are SI measurements, g/mL (or cm3 or cc) are metric.

The answer 11.3 kg/m3 is written in Standard International units, not metric.

Hope this helps. :)

Oh, and I love memorization techniques, especially when I'm trying to learn nursing converstions at the same time.....don't want to get minims and drams mixed up with mass and density. LOL

ooooooooh! Thanks Fun2care. Upon closer examination, I see Moonepie also explained that in her answer. :imbar And this is only chapter 1? I have taken many of my other pre-reqs. and really enjoyed them. I knew this would not be my forte. Pray for me.

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Specializes in Operating Room.
ooooooooh! Thanks Fun2care. Upon closer examination, I see Moonepie also explained that in her answer. :imbar And this is only chapter 1? I have taken many of my other pre-reqs. and really enjoyed them. I knew this would not be my forte. Pray for me.

lol... I know what you mean!!! I had to go to my cousin's house today for a b-day party & was talking to my aunt (a retired RN) about nursing. I told her I was taking chemistry for my future RN-BSN.

She said she was so happy she didn't ever have to take chemistry back then, they only required physical science. (Whatever that is....lol)

So, believe me, if it wasn't for my wanting to get my BSN, I would not be taking chemistry! :chair:

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i made a powerpoint quiz over polyatomic cations & anions that we have to memorize for our first exam. hopefully, it can help some of you as well. :)

if you don't know my site url already, click on my profile.

good luck!

my teacher gave us a little trick which i used on my quiz and it really helped.

cation-i am "positive" i love my cat (positive charge)

anion-i feel "negative" towards onions (negative charge)

both feelings work for me personally so i loved em! :chuckle

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Specializes in Operating Room.

my teacher gave us a little trick which i used on my quiz and it really helped.

cation-i am "positive" i love my cat (positive charge)

anion-i feel "negative" towards onions (negative charge)

both feelings work for me personally so i loved em! :chuckle

thanks paula7. ;)

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my teacher gave us a little trick which i used on my quiz and it really helped.

cation-i am "positive" i love my cat (positive charge)

anion-i feel "negative" towards onions (negative charge)

both feelings work for me personally so i loved em! :chuckle

:chuckle that's funny paula. thanks.

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Specializes in Operating Room.

ok, someone make sure I'm doing this correctly, please! :)

D = ?

V = .52 L

M = 500 mg

I have to convert L to mL and mg to g.

So, I have come up with the math sentence:

D = .5 g

---------

520 mL

Now, if I'm putting this in my calculator correctly, I'm coming up with: 9.615384615 -04. Normally I would put 9.62 g/mL as my answer, but the -04 is confusing me.

I'm not sure on this type of question if I would use significant #s. If so, the answer would be 10.

:confused:

:bowingpur TIA! :flowersfo

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