Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: JonathanEyoon on January 10, 2008, 09:21:58 PM
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I just started chemistry and was introduced to conversion and so on. I was wondering if you guys could recommend some really good self-teach workbooks involving this. Thanks in advance ;)
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The Schaum's Outline Series is a great source for material like that. They offer paperback workbooks. Try that...here is a link:http://www.mhprofessional.com/category/?cat=145
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Thanks alot. I'll try heading over to a local Barnes and Noble to see if they have some I can look at. Any suggestions pertaining to online sources?
I'm just having difficulties with conversions like
"The density of Benzene is 0.879 g/mL. Calculate the mass in grams of 1.00 qt of Benzene."
I have absolutely no idea how I should start questions like this. Like what to look for, what should I identify and things like that.
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You have to remember one equation/definition:
d=m/V
Whenever given mass and volume - just put numbers into equation. Whenever asked to find something else - use simple algebra to solve for the unknown.
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I know I have to use the formula for Density but what i'm having trouble is knowing what units needed to be converted and how.
For instance another question is
one mg/cm^2 = _________ kg/m^2
we've been using the Factor Label Method and it seems really easy when the teacher is doing it but when I try at home I get lost as I have with this problem. I guess starting off and figuring out a method for each unique problem is what's getting me
Any help would be great~
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It is always easier when the teacher does it...just takes pratice....list all the equivalent units for cm^2..don't get frustrated...take it a pice at a time....
SI Units are the standard in Chemistry and Physics. Try this site: http://physics.nist.gov/cuu/Units/
Go to the history first. The history teaches you the base units. Once you know the base units ...then you work on the conversions.
Base units: Length: meter, Mass: kilogram , Time: second , Current: ampere, Temperature: Kelvin,
Amount of a substance: Mole, etc...
To the left you will notice a list that shows you DERIVED...that is your step 2.
I hope this helps. If you get the units down....you get an A++++..
Like: 1 cm^2 = 1 mL
there are 1000 mL = 1000 cm^2 = 1 L
1 g = 1000 mg
1000 g = 1 kg
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Like: 1 cm^2 = 1 mL
there are 1000 mL = 1000 cm^2 = 1 L
Huh?
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MY POINT: If one understands the BASE units in the SI system then one will understand which units one requires to do a conversion....I believe that is CRYSTAL....
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1 cm3 = 1 mL
1000 cm3 = 1000 mL = 1 L
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OK typo 1 cm^3 = 1 mL
1000 cm^3 = 1000 mL = 1L
It was a typo stand coorected....
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Ok i've been trying to do some studying and I think i have it down to a certain degree when it comes to knowing the units...but I'm still confused as to how I should go about solving this problem...
one mg/cm^2 = _________ kg/m^2
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x mg/cm2 [1 kg / 1000 mg][100 cm/1 m]2 = x [CONVERSION FACTOR] kg/m2
Let me know if you don't follow.
Work to convert one unit at a time in steps and make sure units cancel.
Follow red (mg --> kg) and blue (cm2 --> m2) *this conversion is squared because it is cm2 --> m2
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1 kg = 1000 g
and 1000 mg = 1 g
Isn't that right???
hence 1 mg/L = 1 ppm
1000 mg/g
and 1000kg/L
and 1 kg = 1 L
so 1 mg/L = 1 ppm
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1 kg / 1000 mg
When trying to help someone confused - check thrice before posting :(
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The statement above is 1kg/1000 mg...I believe it is
1 kg /1000 g and 1 g/1000 mg there is a factor of 1000 missing
mg/cm^2 (1 kg/1000 g) x (1g/1000 mg).
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x mg/cm2 [1 g / 1000 mg][1 kg / 1000 g][100 cm/1 m]2 = x [CONVERSION FACTOR] kg/m2
Work to convert one unit at a time in steps and make sure units cancel.
Follow red (mg --> kg) and blue (cm2 --> m2) *this conversion is squared because it is cm2 --> m2
[/quote]
Cancelling Units
x mg/cm2 [1 g / 1000 mg][1 kg / 1000 g][100 cm/1 m]2 = x [CONVERSION FACTOR] kg/m2
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Thanks Borek ;)
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x mg/cm2 [1 g / 1000 mg][1 kg / 1000 g][100 cm/1 m]2 = x [CONVERSION FACTOR] kg/m2
Work to convert one unit at a time in steps and make sure units cancel.
Follow red (mg --> kg) and blue (cm2 --> m2) *this conversion is squared because it is cm2 --> m2
Cancelling Units
x mg/cm2 [1 g / 1000 mg][1 kg / 1000 g][100 cm/1 m]2 = x [CONVERSION FACTOR] kg/m2
[/quote]
I'm honestly still not following. Is there an easier way to break it down :-[. This really frustrates me. I'm trying to use the factor label method, but it seems like we're converting two different things and I'm not clear on how to do that exactly, Especially how you get from cm^2 to m^2
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Especially how you get from cm^2 to m^2
1 m2= 100cm x 100cm (length x width) = 10000cm2 :)
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ok how about from cm^3 to dm^3?
I can't understand the math of how you were able to get that.
I understand that 1 meter^2 = 100 cm x 100 cm. which equals 10,000 cm which is 1 meter^2. Buy why would you say 10,000cm^2? Doing that would make it equal to 100,000,000 cm. which does not equal to 1 meter^2. See my confusion here?
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The density of Benzene is 0.879 g/mL. Calculate the mass in grams of 1.00 qt of Benzene."
You are given 0.879 g/mL benzene.
You need g/qt of benzene.
Always begin with what you know.
0.879 g/mL
You need a conversion factor for mL to quarts. So from the conversion table at: http://www.sciencemadesimple.com/metric_conversion_chart.html
You find 1 mL = 0.034 fl oz
1 US quart = 32 fl oz
(Please note I make a distinction about US quart because this is not the same in Imperial designations)
This is how you set up the equation:
(0.879 g/mL) x (1mL/0.034 fl oz) x (32 fl oz/1 quart)
The mL cancel out of the equation.
The fl oz cancel out of the equation.
And you are left with g/quart.
When you do the calculation you get: 827.29 g/quart = 827 g/quart.
Now you question about cm^3 and dm^3...this is where learning conversion is important...where the tables become useful:
1 cm^3 = 1 mL
1000 mL = 1 L
1L = 1 dm^3
This is a cubic decimeter and is a unit of volume NOT a unit of length..
Like a cubic centimeter is a unit of volume.
Are yiou getting it???
Cubic decimeters are used in Physical Chemistry it is a common unit of measure for VOLUME. Often used for the volume an amount of gas occupies.
You have to recognize anything cubed is a volume...like think of a rubix cube....a cube is 3 dimensional and has a volume...
Something squared ia an area....like an area rug in your home....anything squared ai an area L x W is a squared area.
Anything cubed has a volume.
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So since you are converting from cm^3 to dm^3
I already stated:
1 cm^3 = 1 mL
1000 mL = 1 L
so then 1000 cm^3 = 1 L
since 1 dm^3 = 1 L
then 1000 cm^3 = 1 dm^3
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I can't understand the math of how you were able to get that.
I understand that 1 meter^2 = 100 cm x 100 cm. which equals 10,000 cm which is 1 meter^2. Buy why would you say 10,000cm^2?
10000 comes from 100 x 100, cm2 comes from cm x cm.
EDIT: There is a difference between 100002cm and 10000cm2
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OK...let me try it this way:
a cm is a unit of length
a m is a unit of length
a dm is a unit of length
a mm is a unit of length
When you cube any of these they become VOLUMES
cm x cm x cm = cm^3 = volume
m x m x m = m^3 = volume
dm x dm x dm = dm^3
mm x mm x mm = mm^3 = volume
When you square any of these they become AREAS
cm x cm = cm^2 = area
m x m = m^2 = area
dm x dm = dm^2 = area
mm x mm = mm^2 = area
If we are still on how to go from cm^2 to M^2
100 cm = 1m
(100 cm)^2 = 1 m^2 (you have to square the entire quantity)
100 x 100 = 10,000 then tag on the units cm^2
So this gives you 10,000 cm^2 = 1 m^2
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ok I think i'm actually starting to get it now. I was just really, really, REALLY confused about the cubic and square values.
When it comes to Volume,
so dm^3 = 1 Liter
cm^3 = 1 milliliter
I have a question. So it'll take 1000 milliliter's to equal one Liter, so does this mean it'll take 1000cm^3 to equal one dm^3?
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WOO HOO...YOU GOT IT!!!!!!
I had the same problem when I was learning it...so do not worry...as you were writing...I began to see what you did not get...it is the meaning of the conversion that you need to get....and now you are on your way...GOOD JOB!!!!!
Let me know if you need more help/explanation...what you just wrote is 100% Correct....
1000 mL = 1L
1000 mL = 1000 cm^3
1000 cm^3 = 1 L
1L = 1 dm^3
so YES 1000 cm^3 = 1dm^3
so you now see: 1000 mL = 1000 cm^3 = 1L = 1dm^3
they are all equal and all a conversion of one unit to another
And that is the way you will get it!!!!!! Good For You!!!!