Gas law問題

cellmembrane

A basketball of volume 0.00710 m3 initially air at 25 Celsius and 101 kPa.

a)The ball is pumped into more air, without a change in the volume and temperature,
   using a hand pump.

(i)Suppose air of 250 cm3 at 101 kPa is pumped into the ball in each stroke.How many strokes are needed to increase the gas pressure inside the ball at least 55 kPa?

答:
Let the no. of stroke are needed be n
According to boyle's law,pV=pV
1.01x 10^5 x 0.00710=(1.01+0.55)x 10^5 x (250x 10^-6 x n)
請問一下咁樣列式岩唔岩?

THANKS!!

bosukoyo

我想問呢 點解  你101 kPa 可以係 1.01X10^5 但55kPa 就變左 55X10^5 既??

cellmembrane

sorry 打少左tim

thx


請問ideal gas law中既Volume係指邊一種,容器,gas定係total molecule既volume?

thanks~


版主按:請善用編輯功能

Ivanhy92

如果Ideal Gas Law 能夠apply的話, 那麼每粒 molecule 本身的 size近乎0 (negligible size), 所以這裡的volume指的就是gas volume, 不會有樓上所說的問題.

即係: Empty Space + Molecule size = Capacity of container
現在 Ideal gas情況下 Molecule size近乎 0, 所以 Empty Space ~ Capacity of container = V

若果在真實情況下, gas molecule本身佔有一定的volume (假設所有molecule的size總和為b, Capacity of container = V), pV = nRT 的公式將會變為 p(V-b) = nRT

希望我沒有放山埃吧

cellmembrane

The root-mean-square speed of helium gas molecules, each of mass m,is v[rms] ,Which of the following statements is/are correct?

(1)All molecules move randomly with speed v[rms].
(2)The average speed of the molecules is v[rms].
(3)The average kinetic energy of the molecules is 1/2mv[rms]^2

A.(2)only
B.(3)only
C.(1) and (2)only
D.(1) and (3)only

請問點解個答案係B?