# Chemistry

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Can anyone help and check my answers?

A. 8.43 cm to millimeters--- 84.3 millimeters.

B. 2.41x10^2 cm to meterss--- 0.0241 meters.

C. 294.5 nm to centimeters--- I don't know how to concert this.

D. 1.445x10^4 m to kilometers--- 0.001443 Kilometers.

E. 235.3 m to millimeters--- 235300 millimeters.

F. 903.3 nm to micrometers-- I don't know hot to convert this.

Can anyone also tell me what "nm" means?

Thanks!

• Chemistry -

A. 8.43 cm to millimeters--- 84.3 millimeters. OK

B. 2.41x10^2 cm to meterss--- 0.0241 meters.
No. Don't let the exponent get to you. In simpler ones, as in this one, remove the exponent first to obtain 2.41 x 10^2 = 241 cm and divide by 100 to convert to meters = 2.41 meters.

C. 294.5 nm to centimeters--- I don't know how to concert this.
1 nm = 1 nanometer = 1 x 10^-9 meter. The easiest way to convert all of these is to change everything to meters and go from there. There are 1 x 10^9 nm = 1 meter and 100 cm = 1 meter so
294.5 nm x (1 m/1 x 10^9 nm) x (100 cm/1m) = 2.945 x 10^-5 cm. Notice how the units cancel. The first factor converts nm to m (see the nm unit cancels and leaves m); the second factor converts to cm(see the m cancels and leaves cm).

D. 1.445x10^4 m to kilometers--- 0.001443 Kilometers.
I came out with 14.45 km. Check my work.

E. 235.3 m to millimeters--- 235300 millimeters.
That't what I have.

F. 903.3 nm to micrometers-- I don't know hot to convert this.
There are 1 x 10^9 nm in 1 m and there are 1 x 10^6 micrometers in 1 m.
I came out with 0.9033 micrometers. Check my work.

Can anyone also tell me what "nm" means?
nm stands for nanometers. The n for nano and m for meter. You should know the prefixes. Here is a site that gives ALL of the prefixes.
http://physics.nist.gov/cuu/Units/prefixes.html

• Chemistry -

Thank you so much!

Im still a little confuse on the nanometers.

on problem c im not sure how you ended up getting 2.945 x 10^-5 cm. Could you maybe explain a little more to me?

• Chemistry -

C. 294.5 nm to centimeters--- I don't know how to convert this.

1 nm = 1 nanometer = 1 x 10^-9 meter. The easiest way to convert all of these is to change everything to meters and go from there. There are 1 x 10^9 nm = 1 meter and 100 cm = 1 meter so
294.5 nm x (1 m/1 x 10^9 nm) x (100 cm/1m) = 2.945 x 10^-5 cm. Notice how the units cancel. The first factor converts nm to m (see the nm unit cancels and leaves m); the second factor converts to cm(see the m cancels and leaves cm)

The above is your original question and my response. Here is the math part revisited.
294.5 nm x (1 meter/1 x 10^9 nm) x (100 cm/1 meter) =
294.5 x 1 x 10^-9 x 1 x 10^2 (note that the 1 x 10^9 in the denominator was moved to the numerator by changing the sign of 1 x 10^9 to 1 x 10^-9 and I changed the 100 to 1 x 10^2 just so everything would be in exponent form). To multiply exponents we add them so
294.5 x 10^-9 x 10^2 = 294.5 x 10^-7. However, we usually leave numbers in exponential form with the decimal point just after the first digit; therefore, we move the decimal to the left two places to make it 2.945 and we take two places away from the 10^-7 by making it 10^-5. Another way to see it is this:
294.5 x 10^-7 = 0.00002945 which is the decimal point moved to the left 7 places from its original site. Then we move it back to the right 5 places to get 2.945 and since we have moved it 5 spots, then we follow with the 10^-5 exponent.

• Chemistry -

Thank you guys sooo much, this definately helped a lot!

• Chemistry -

ITS THE ZUMDHAL BOOK!

• Chemistry -

8.43 cm to mm