8.98 dm3 of hydrogen gas is collected at 38.8 °C. Find the volume the gas will occup at -39.9 °C if the pressure remains constant.

V₂ = 6.7 dm³

Explanation:

Given data:

Volume of hydrogen = 8.98 dm³

Initial temperature = 38.8 °C

Final volume of hydrogen gas = ?

Final volume = -39.9°C

Solution:

Initial temperature = 38.8 °C (38.8 + 273 = 311.8 K)

Final volume = -39.9°C (-39.9 + 273 = 233.1 k)

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

V₂ = V₁T₂/T₁  

V₂ = 8.98 dm³  × 233.1 K / 311.8 K

V₂ = 2093.238 dm³.K /311.8 K

V₂ = 6.7 dm³

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.