The temperature of 360 mL of a gas is decreased from 20°C to -40°C while the pressure is held constant What is the new volume of the gas?
A
180 mL
B.
286 ml
C453 mL
D.
720 ml

The answer is: B. 286 mL

Explanation:

Given:

V₁ = 360 mL = 0.36 L

T₁ = 20°C = 293 K

T₂ = -40°C = 233 K

Constant pressure

Question: What is the new volume of the gas, V₂ = ?

The relation between the temperature and the volume at constant pressure is known like the Charles's law

286.3 mL

Explanation:

The question specifies that pressure was held constant, this immediately reminds us of Charles law. The volume of a given mass of has is directly proportional to its temperature at constant pressure.

From

V1/T1 = V2/T2

V1= initial volume = 360 ml

T1 = initial temperature= 20°C +273= 293K

T2= final temperature= -40°C + 273= 233K

V2= final volume =

V2= V1T2/T1

V2= 360 × 233/ 293

V2= 286.3 mL

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%