Concept Development Practice Page

20-1

Gases

1. A principle difference between a liquid and a gas is that when a liquid is under pressure, its

volume

(increases) (decreases) (doesn't change noticeably)

PHYSICS

and its density

SIGHS

(increases) (decreases) (doesn't change noticeably)

When a gas is under pressure, its volume

(increases) (decreases) (doesn't change noticeably)

and its density

(increases) (decreases) (doesn't change noticeably)

1

2. The sketch shows the launching of a weather balloon

at sea level. Make a sketch of the same weather balloon 1

when it is high in the atmosphere. In words, what is

different about its size and why?

1

1

The answer is below

Explanation:

The main difference between a liquid and a gas is that when a liquid is under pressure, its volume "won't change apparently. The reason is that the distance between the molecules of a liquid is relatively small, and the molecules of a liquid extensively withstand the compressive forces. This is similar to the distance between the molecules of a solid."

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more