bamdavis

It was found that one ocular micrometer equaled 0.025 mm at 100X power. If the wing of a fruit fly was measured to be 80 ocular micrometer units at a magnification of 100X, what is the length of the wing in mm? I have two answers, but i don't know which is right? 0.025mm x 80um = 2mm or 0.025 mm x 0.08mm = 0.02 mm in this one i converted the 80 ocular micrometer units to millimeters.

i dont have my periodic table

I have some questions about finding masses or moles of certain compounds over water but i need a chart showing the pressure at certain temperatures. for example A student collects 41.1ml of oxygen gas at 737 torr and 25C by displacement of water. What amount in moles of oxygen is present in this sample? So i need the torr pressure at 25C I need a chart showing these pressure and temperatures but i cant find any on the web.

I dont understand

this is just from a lab i did today. we put 5ml of an unknown volatile in a volumetric flask, put tin foil on the top and poked a hole in it. We heated it in a beaker filled with boiling water to get it to evaporate. After it evaporated we cooled it to condense into a liquid and then weighed it.

Must find the molar mass of an unknown volatile liquid. Using the equation PV=mRT M P= 102.4 KPA V=0.098L T= 373 K Mass= 0.1647 g R= constant gas for KPA= 8.312 KPA Rearrange it to M= mRT PV i got M= (0.1647)(8.312)(373) (0.098)(102.4) M= 50.8841 g/mol

Ill say what i think, then you give more hints, or the answer. 1. I think you have to weigh it fast or some of the liquid will turn to vapour again? 2. i have no idea. 2. your boiling the water out of the liquid?

1. After the vapour has condensed to a liquid why is it important to obtain the weight of the liquid "without delay" in number 8? 2. What assumptions are made about the vapour of the substance in this labratory? Lab Info 1. Weigh a clean , dry 100ml volumetric flask together with a square of aluminum foil to 4 decimal places. Record this mass in the data table. 2. Pour 3 to 5 ml of an unknown liquid into the volumetric flask. Record the unknown letter in the data table. 3. Cover the flask with the foil and make a tight seal. Make a small hole in the top of the foil using a pin. 4.Place a 600ml beaker on a hot plate and lower the volumetric flask into the beaker to within 1 cm of the bottom. Use a clamp to hold the volumetric flask in place. Pour water into the beaker to cover at least the round portion. 5. Gently boil the water in the beaker until all of the unknown liquid vapouraizes in the flask and then for about additional minutes. The total time for vapourization will be about 15 minutes.Record the temperature of the water in the data table. 6. Quickly remove the flask from the beaker and cool to room temperature by running cold water over the surface of the flask. All the vapour will condense to a liquid. 7. Dry the flask with paper towel and by blowing air over the surface. 8. Weigh the cooled and dry flask and liquid without delay. Record this value in the data table. 9. To determine the volume of the volumetric flask, fill to the top with water and pour this water into a graduated cylinder. 10. Record the the barometric pressure in the data table.