Today we did a small lab where we learned about how to measure things. We focused on answering questions like, What is the density of helium? and How can we characterize helium?
First we did some background research, which was mostly Andrew telling us about measuring different things and how it works. These are exact measurements that never change:
Length: meter (m)
Volume : liter (L) = 1dm^3
Mass: Gram (g) = 1cm^3 of H2O = 1mL (also cc (cubic centimeters)
Time: Seconds (s)
Amount of Stuff: Mole (mol)
Temperature: Kelvin (k) - Degrees Celcius + 273.15 = k
Ratios and Comparisons:
Velocity: Distance/Time = d/t = m/s - if you know at least two of the components you can find the missing one
Molarity: mol/L - for a solution
Density: mass/volume = g/mL
- Buoyancy = level to which two substances density's match
Everything comes down to understanding density
After learning our background research we did the actual experiment to find the density of helium. To find this we filled a small balloon with helium. Then we had to make the balloon the same density as the normal air. To do this we added mass, by sticking tape on the balloon to make it buoyant with the air.
Density of air = .001225 g/gm^3
Volume of a sphere = 4/3 (pi) r^3 = 2572.44cm^3
Then we weighed the balloon and tape on a gram scale ( The scale was not sensitive enough so we had to estimate)
Balloon + Tape = 2.5g + Helium = 3.15g
Helium = .65g
.001225g/1cm^3 (2572.44cm^3)
=3.151239 g
= .00025g
---------------
cm^3
The main challenge in this activity was see how you can measure something that is lighter than air and that since helium still has mass and volume we can still measure it. By doing the calculations to figure out this lab, we got a much more exact answer. I learned more about how to characterize an element and terms on measuring. If we could redo the experiment we would have used a bigger balloon so it would be easier to measure as well as have a more sensitive scale to weigh the balloon and tape.
First we did some background research, which was mostly Andrew telling us about measuring different things and how it works. These are exact measurements that never change:
Length: meter (m)
Volume : liter (L) = 1dm^3
Mass: Gram (g) = 1cm^3 of H2O = 1mL (also cc (cubic centimeters)
Time: Seconds (s)
Amount of Stuff: Mole (mol)
Temperature: Kelvin (k) - Degrees Celcius + 273.15 = k
Ratios and Comparisons:
Velocity: Distance/Time = d/t = m/s - if you know at least two of the components you can find the missing one
Molarity: mol/L - for a solution
Density: mass/volume = g/mL
- Buoyancy = level to which two substances density's match
Everything comes down to understanding density
After learning our background research we did the actual experiment to find the density of helium. To find this we filled a small balloon with helium. Then we had to make the balloon the same density as the normal air. To do this we added mass, by sticking tape on the balloon to make it buoyant with the air.
Density of air = .001225 g/gm^3
Volume of a sphere = 4/3 (pi) r^3 = 2572.44cm^3
Then we weighed the balloon and tape on a gram scale ( The scale was not sensitive enough so we had to estimate)
Balloon + Tape = 2.5g + Helium = 3.15g
Helium = .65g
.001225g/1cm^3 (2572.44cm^3)
=3.151239 g
= .00025g
---------------
cm^3
The main challenge in this activity was see how you can measure something that is lighter than air and that since helium still has mass and volume we can still measure it. By doing the calculations to figure out this lab, we got a much more exact answer. I learned more about how to characterize an element and terms on measuring. If we could redo the experiment we would have used a bigger balloon so it would be easier to measure as well as have a more sensitive scale to weigh the balloon and tape.