Homework Help (Chemistry)

Question

A) A sample of SO₂ contains 1.98*10^-3 moles. How many mL will it occupy? The density of the gas is 2.168g/L.

B)If the density of SO₂, were to increase because the temperature decreased, would the volume of the gas increase or decrease?

C) If you were to fill a toom that was 16.5 ft by 8.9 ft completely of SO₂, how many grams of gas would you have?

Answer 1

A) Convert moles to grams to use the density (2.168 g/L) to find the volume in mL.

 

 

molar mass (mass of 1 mole of SO₂): 32.06 + 2(15.999) = 64.06 g/mol

 

 

(1.98 x 10^-3 mole)(54.06 g/mole)/[(2.168 g/L)(1L/1000 mL)] = 49.4 mL

 

 

 

B) Look at the density, 2.168 g/L.  Density can increase or decrease depending on how temperature changes.  It has units of mass in grams over volume in liters.  If the density increases and the mass stays the same, then the volume has to decrease.

 

We know that most substances expand in volume when heated and contract when cooled.  We can use this background knowledge to check our answer.

 

 

C) We need to know the third dimension of the room to get a volume for the room.  But say the room has dimensions 16.5 ft x 8.9 ft x 10 ft.

 

 

The volume would be (16.5)(8.9)(10) = 1450 ft³.  Since 1 ft³ = 28.3 L, 1450 ft³ = 4.16 x 10⁴ L.

 

 

So, (4.16 x 10⁴ L)(2.168 g/L) = 90,100 g

 

 

This would be the procedure to find the mass of SO₂ for the room.  Once again, we need a third dimension of the room to find the correct mass.