[pluto]

im in AP chem and i keep coming up with the wrong answer

A cylindrical glass tube 11.8 cm in length is filled with ethanol. The mass of ethanol needed to fill the tube is found to be 22.5 g. Calculate the inner radius of the tube in mm. The density of ethanol is 0.789 g/mL.

[azmanam]

what answer do you keep coming up with?  show your work.

[dabaichi]

Since you keep coming with the wrong answer, I'll help you with this. So you know that the volume for a cylinder is pi x raidius squared x length of tube, the volume for the tube would be 11.8*pi*r^2. You can find the volume of ethanol when its mass and its density is given. Simply use 22.5g * 1ml / .789g. This volume would be equivalent to the volume of the tube. Also, since cm^3 is 1 ml, you don't have to change units for this problem as long as your radius is in cm. So 11.8pi*r^2=22.5g*1ml/.789g . You do the math.