[JonathanEyoon]

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

[Alpha-Omega]

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

[JonathanEyoon]

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.

[Borek]

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.

[JonathanEyoon]

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~

[Alpha-Omega]

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

[Borek]

Like:  1 cm^2 = 1 mL

there are 1000 mL = 1000 cm^2 = 1 L

Huh?

[Alpha-Omega]

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....

[agrobert]

1 cm³ = 1 mL

1000 cm³ = 1000 mL = 1 L

[Alpha-Omega]

OK typo 1 cm^3 = 1 mL

1000 cm^3 = 1000 mL  = 1L

It was a typo stand coorected....

[JonathanEyoon]

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

[agrobert]

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

[Alpha-Omega]

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

[Borek]

1 kg / 1000 mg

When trying to help someone confused - check thrice before posting

[Alpha-Omega]

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).